Micro Electromechanical System (MEMS) microshutter arrays are being developed at NASA Goddard Space Flight Center for use as a field selector of the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). The microshutter arrays are designed for the spontaneous selection of a large number of objects in the sky and the transmission of light to the NIRSpec detector with high contrast. The JWST environment requires cryogenic operation at 35 K. Microshutter arrays are fabricated out of silicon-on-insulator (SOI) silicon wafers. Arrays are close-packed silicon nitride membranes with a pixel size of 100 x 200 μm. Individual shutters are patterned with a torsion flexure permitting shutters to open 90 degrees with a minimized mechanical stress concentration. Light shields are processed for blocking light from gaps between shutters and frames. The mechanical shutter arrays are fabricated using MEMS technologies. The processing includes multi-layer metal depositions, the patterning of magnetic stripes and shutter electrodes, a reactive ion etching (RIE) to form shutters out of the nitride membrane, an anisotropic back-etch for wafer thinning, followed by a deep RIE (DRIE) back-etch to form mechanical supporting grids and release shutters from the silicon substrate. An additional metal deposition is used to form back electrodes. Shutters are actuated by a magnetic force and latched using an electrostatic force. Optical tests, addressing tests, and life tests are conducted to evaluate the performance and the reliability of microshutter arrays.

Semiconducting FeSi₂ has attracted considerable amount of research interest in the past decade for its potential applications as a silicon-based light emitting material. In this work, FeSi₂ precipitates were formed in Si by iron implantation into silicon using a metal vapor vacuum arc ion source. The structures and light emitting properties of these ion-beam-synthesized FeSi₂ precipitates were studied in details using various characterization techniques, including transmission electron microscopy (TEM) and photoluminescence measurements. It was found that the implantation temperature played an important role on the dislocation loop formation and hence the FeSi₂ phase formation during the subsequent thermal annealing. Photoluminescence (PL) spectra were measured as a function of temperature from 80 to 300 K. Combining the TEM and PL results, the origins of the PL could be distinguished to be either from the defect-related emission of Si or from the FeSi₂ precipitates. The FeSi₂ precipitates were found to be highly-strained or relaxed depending on the implantation and annealing conditions. The band gap energy of the relaxed samples was determined to be about 11 meV higher than that of the highly strained samples. Simple metal-oxide-semiconductor (MOS) diode structures were fabricated to study the electroluminescence (EL) properties from this FeSi₂/Si system. Preliminary results showed that clear EL signals were obtained even at room temperature for samples prepared at appropriate conditions. There are significant differences between the EL and PL spectra and the mechanisms of the EL emission has yet to be further investigated.

The drawing of optical fiber is essentially a stabilization process with a 'slow’ feedback system used to control diameter drift. Such a system is capable of producing high precision fiber with a ±0.3 μm deviation around the mean diameter being standard even on a high-speed commercial tower. However an emerging demand for even greater precision in fiber diameter has focused attention on the neck-down process itself and the effect of furnace operating conditions on the stability of this crucial stage. In this paper we present the results of an extensive experimental study into the nature of cladding diameter variations along optical fibers based on real-time measurements made during fiber drawing. It was found that the statistical distribution of cladding diameter measurements is never Gaussian with multiple peaked distributions being quite common. Power spectra indicate that the change in diameter is generally random but with detectable maximum frequency components up to 5-10 Hz. An incorrectly set up furnace can produce strongly periodic variations. Results will be presented that quantify the impact of furnace temperature, furnace purge gas flow and iris aperture on the variation in fiber diameter. Some evidence of 'diameter modes’ -- that is, preferred diameters separated by gaps in the observed measurements -- has been found. The overarching conclusion is that better process control is not the route to reducing variation in fiber diameter. Rather the solution lies in moderating the extent to which short-time scale variations in the temperature and flow fields within the furnace interact with the preform neck-down region.

In the last decade, the synthesis and characterization of nanometer sized carbon clusters have attracted growing interest within the scientific community. This is due to both scientific interest in the process of diamond nucleation and growth, and to the promising technological applications in nanoelectronics and quantum communications and computing. Our research group has demonstrated that MeV carbon ion implantation in fused silica followed by thermal annealing in the presence of hydrogen leads to the formation of nanocrystalline diamond, with cluster size ranging from 5 to 40 nm. In the present paper, we report the synthesis of carbon nanoclusters by the implantation into fused silica of keV carbon ions using the Plasma Immersion Ion Implantation (PIII) technique, followed by thermal annealing in forming gas (4% ²H in Ar). The present study is aimed at evaluating this implantation technique that has the advantage of allowing high fluence-rates on large substrates. The carbon nanostructures have been characterized with optical absorption and Raman spectroscopies, cross sectional Transmission Electron Microscopy (TEM), and Parallel Electron Energy Loss Spectroscopy (PEELS). Nuclear Reaction Analysis (NRA) has been employed to evaluate the deuterium incorporation during the annealing process, as a key mechanism to stabilize the formation of the clusters.

We propose a scheme for electron spin quantum computing based on electron spin in semiconductors. This scheme shares many similarities with the existing Kane nuclear spin proposal. We show how quantum computation may be carried out in this proposal, including single qubit rotations and CNOT gate. We show how this control can potentially lead to gate speeds 100-1000 times faster than the existing nuclear spin proposal, and up to 10⁶ times faster than a typical electron spin dephasing time, T₂(_e).

We report on progress towards a charge-based qubit using phosphorus atoms implanted in a silicon substrate. Prototype devices have been fabricated using standard lithographic techniques together with a new method of controlled single ion implantation using on-chip detector electrodes. Positional accuracy of the implanted ions was achieved using a nanoaperture mask defined using electron beam lithography. The two implanted phosphorus atoms are positioned ~50 nm apart, to form a qubit test device. A series of process steps has been developed to repair implant damage, define surface control gates, and to define single electron transistors used for qubit readout via the detection of sub-electron charge transfer signals. Preliminary electrical measurements on these devices show single charge transfer events that are resilient to thermal cycling.

We report recent progress in single keV ion implantation and online detection for the controlled implantation of single donors in silicon. When integrated with silicon nanofabrication technology this forms the “top down” strategy for the construction of prototype solid state quantum computer devices based on phosphorus donors in silicon. We have developed a method of single ion implantation and online registration that employs detector electrodes adjacent to the area into which the donors are to be implanted. The implantation sites are positioned with nanometer accuracy using an electron beam lithography patterned PMMA mask. Control of the implantation depth of 20 nm is achieved by tuning the phosphorus ion energy to 14 keV. The counting of single ion implantation in each site is achieved by the detection of e^-/h⁺ pairs produced by the implanted phosphorus ion in the substrate. The system is calibrated by use of Mn K-line x-rays (5.9 and 6.4 keV) and we find the ionization energy of the 14 keV phosphorus ions in silicon to be about 3.5-4.0 keV for implants through a 5 nm SiO₂ surface layer. This paper describes the development of an improved PIN detector structure that provides more reliable performance of the earlier MOS structure. With the new structure, the energy noise threshold has been minimized to 1 keV or less. Unambiguous detection/counting of single keV ion implantation events were achieved with a confidence level greater than 98% with a reliable and reproducible fabrication process.

Incoherent quantum charge tunneling forms the basis of semiconductor devices. However it is well known from atomic and optical work, that coherent tunneling can be significantly faster and in principle, coherent transfer is dissipationless, i.e. the charge being transferred does not exchange heat with the environment. Furthermore, adiabatic controls are inherently robust provided the adiabaticity criterion is satisfied. Adiabatic control methods are therefore preferable to ensure high-fidelity operation despite increased operating time. We describe recent work towards understanding charge transfer mechanisms based on adiabatic passage techniques with all-electrical controls in three-, five- and seven-dot systems based on Coherent Tunneling Adiabatic Paassage (CTAP). We derive analytical values for the important eigenstates and the adiabaticity criteria for these schemes. These analytical results allow us to make comments regarding the scalability of these schemes to realistic quantum networks.

An all-silicon quantum computer architecture using ²⁹Si nuclear spins qubits buried in the spin-free matrix of ²⁸Si has been suggested. It requires an array of micro-magnets which impose a large magnetic field gradient along the chain of the ²⁹Si nuclear spins qubits, which allow for the NMR frequency difference between two neighboring ²⁹Si qubits. In this work, we report on the successful fabrication of an array of NiFe (Ni45%-Fe55%) micro-magnet stripes (the cross-section 1.2x1 μm²) formed directly on natural Si wafers using reactive ion etching (RIE) with the NH3-CO-Xe gas mixture. The magnetic field gradient calculation with the finite element method with the geometry of the fabricated NiFe stripes predicts the gradient of 0.4T/μm at the distance 100nm away from the micro-magnet when the stripes are placed in the static magnetic field of 6T for the NMR measurement. The magnetic property of fabricated NiFe stripes was also measured with SQUID, and confirmed that saturation magnetization hadn’t been deteriorated through RIE process.

By capactively coupling sensitive charge detectors (i.e. single-electron transistors - SETs) to nanostructures such as quantum dots and two-dimensional systems, it is possible to investigate charge transport properties in extremely low conduction regimes where direct transport measurements are increasingly difficult. Ion-implanted nano-MOSFETs coupled to aluminium SETs have been constructed in order to study charge transport between locally doped regions in Si at mK temperatures. This configuration allows for direct source-drain measurement as well as non-invasive charge detection. Of particular interest are the effects of material defects and gate control on charge transport, which is of relevance to Si-based quantum computing.

The long coherence times of both nuclear and electron phosphorus donor spins in silicon make them promising qubits for a scalable quantum computer. In such a system, the single qubit operations could me implemented via the application of resonant RF fields, while the inter-qubit interactions are mediated via the exchange interaction between neighboring donor electrons. This interaction could be controlled, to some extent, via the application of potential biases to control electrodes, which would perturb the electron wavefunctions. The degeneracy of the conduction band minima in silicon leads to interference effects between the donor wavefunctions resulting in a strong dependence of the strength of the exchange coupling on the relative separation of the phosphorus donors, this can have significant consquences to the fabrication of a donor spin based quantum computer. We present calculations of the donor electron exchange coupling as a function of the relative donor position, using donor wavefunctions that have been calculated by direct diagonalisation of the system Hamiltonian, in a basis of the silicon conduction band Bloch functions, beyond the standard effective mass approximation. We consider the effects of non-Coulombic donor potentials, as well as an applied lattice strain, which breaks the degeneracy of the conduction band minima and can be used to damp the oscillatory behavior of the exchange energy. We discuss these results and their implications with respect to fabrication of a scalable donor spin quantum computer.

We report on the results of our study on the micro/nano-scale design, fabrication and integration of waveguide arrays for optical printed circuit boards (O-PCBs) and VLSI micro/nano-photonic applications. The O-PCBs are designed to perform the functions of transporting, switching, routing and distributing optical signals on flat modular boards or substrates. We have assembled O-PCBs using optical waveguide arrays and circuits made of polymer materials and have examined information handling performances. We also designed power beam splitters and waveguide filters, using nano-scale photonic band-gap crystals, for VLSI photonic integration application. We discuss potential applications of polymer optical waveguide devices and arrays for O-PCB and VLSI micro/nano-photonics for computers, telecommunications, and transportation systems.

InP-based micro-opto-electro-mechanical systems (MOEMS) for the long wavelength range (1.3 and 1.55 μm) have been extensively investigated during the last years. The fabrication of ultra-thin and hence ultra-flexible structures that can be actuated electrostatically was limited by residual strain within the structural layers. Highly flexible membranes are necessary if the tuning voltage is to be kept below 10 V and a wide tuning range is required. Adapting the metal-organic vapor phase epitaxial growth conditions, the residual strain was significantly reduced, allowing the fabrication of InP membranes as thin as 30 nm. Tunable micro-cavities (L_cavity=0.5 λ, λ=1.55 μm) with a InP membrane thickness of only 123 nm show an optical tunability of up to 30.5 nm/V² and a maximum tuning range of more than 160 nm. When reducing the thickness to 123 nm (which corresponds to λ/4) a significant deformation of the membranes was observed that has to be taken into account for the fabrication of MOEMS since additional losses are created. A highly selective, widely tunable filter for dense wavelength division multiplexing systems (WDM) was fabricated and exhibits a selectivity of < 0.4 nm throughout the entire tuning range of 48 nm.

Many micro devices have been successfully injection molded. Efforts need to be made to identify the significant factors that affect micro filling behaviors. The objective of this paper is to investigate the application of injection molding and injection compression molding processes to produce diffraction gratings. A mold was designed to produce a diffraction rating connected with the fixed bushing. The combined part was verified to have a good diffraction performance. Integrated grating eliminates the assembly cost and error. Photolithography was applied to make the mold insert. The Taguchi method and parametric analysis were applied to study the effects of molding parameters on grating quality. The design, fabrication of structured mold surfaces and the results of the replication by injection molding (IM) and injection compression molding (ICM) are presented and compared.

We present the results on the monolithic integration of self-assembled GaAs micromirrors with light emitting diodes. The micromirrors were self-assembled by the strain-driven mechanism, which control the micromirror standing position and flatness. The device epi-layer structure and the fabrication processes were optimized. Self-locking mechanism was also employed to precisely position and enhance the mechanical strength of the assembled micromirrors. Light emission was observed on the integrated devices. For the first time, the effectiveness of the self-assembled micromirrors was confirmed in the monolithic integration with LEDs on GaAs. This result shows the feasibility of GaAs-based micro-opto-electromechanical systems for photonics applications.

High quality thermoset polymer solutions are available from several commercial suppliers. These are suitable for forming thin films for optical waveguides because of their high transmission, suitable refractive indices and thickness uniformity of films obtained by spinning solutions on a substrate such as silicon. The solution's viscosity and the spinning speed determine the thickness of resulting films. The plasma etch rate was examined for trenches (of the order of 1 μm depth, suitable for photonic waveguide fabrication) formed in such films from a relatively high viscose polymer solution (UV15 from Master Bond). The cross-link density of the polymer is dependent on its curing process, that is, the exposure to ultra-violet light radiation and heat. The curing process can have a profound affect on the etch rate. Different paths were taken in the curing and etching process of the spun polymer film in order to examine the relation between the cross-link density and the polymer etching process. We examine the polymer films using FTIR to qualitatively measure the cross-link density and DSC for changes in the glass transition temperature (Tg). FTIR is used to show if chemical changes occur for different levels of curing. Determining Tg is important because this will show how it changes with the baking step. We have observed that for films with low Tg, the plasma etch process can cause the polymer surface to flow and hence wrinkle. Post-curing at higher temperatures increases Tg. By choosing appropriate curing steps, Tg and the etch rate can be optimized to obtain an optimum etch rate and preserve the smooth polymer surface during etching.

This paper describes a simple and inexpensive technique to design and fabricate polygon microlens array using thermal pressing technique. Polygon microlens array molds were fabricated by using lithography and electroforming process. Microlens pattern was designed on a photomask and transferred to a substrate through photoresist patterning. The electroforming technology was used to convert the photoresist microlens patterns into metallic molds. A hot pressing machine was used to replicate microlens array in PC substrate. The compression pressure, temperature, and pressing time were key parameters to design and manufacture microlens array. The optical properties of these microlenses have been characterized by measuring their focal lengths. The average cylindrical microlenses radii of curvature were 315μm~420μm and the average sag heights were 2.98μm~4.03μm.

Magnetic actuation has been very successful in both macro and micro scales and magnetic microactuators with different microstructures have also been extensively studied. Almost all of these microactuators are based on the electromagnetic effect and the force is generated by the electromagnetic coil, between the soft magnetic core and the (magnetic) cantilever. To integrate all of these magnetic components on the same chip, microstructures with different aspect ratios were fabricated in a single layer by using a photolithography process using the negative photoresist SU-8 2000. A copper microcoil, a permalloy core and a nickel metal post for suspending a cantilever beam were electroplated on the same seed layer with aspect ratios varying from 1:1, 5:1 to 10:1, and the dimensions of the features ranging from 25 μm to 500 μm. The three different features were fabricated separately in three layers. Different viscosity of SU-8 2000 was used in three layers. 50 μm, 80 μm and 200 μm thick SU-8 are used to pattern the molds for electroplating three different features. 25 μm thick copper microcoils with an aspect ratio 1:1 was first electroplated on the Ti/Cu/Ti seed layer. This is followed by electroplating of 50 μm thick permalloy layer with an aspect ratio 10:1 on the same seed layer. A 100 μm thick copper post with an aspect ratio 5:1 was electroplated on to the same seed layer in the next step. SU-8 resist molds were removed between each of these layers. Finally, the residual SU-8 was cleaned by CF₄ plasma etching. The coils have 19 turns with a footprint area of 10 mm². The microcoils were tested to ascertain their maximum current densities before burnout. Similarly, the magnetic properties of the Permalloy core were also tested. The profiles of different layers and the coil and permalloy core test results were discussed in detail in this paper.

An adhesive bonding technique for wafer-level encapsulation of high aspect ratio microstructures (HARMS) is presented. The adhesive material is spin coated on a cap wafer and structured prior to bonding. Thus sealed cavities of variable height are created in the bonding layer. SU-8 negative photoresist is used as the adhesive material in combination with miscellaneous surface materials: silicon, silicon dioxide and aluminum. The influences of the bonding process parameters - bonding pressure, bonding temperature and process time - as well as the SU-8 layer properties on the bond strength and the homogeneity of the bond have been investigated. To evaluate the process conditions the shear strength of the bond has been measured according to the ASTM standard D 1002 for adhesive bonds. Each bond interface was tested by 32 test specimens of 10 by 10 mm² side length. With optimal process conditions shear strength of 19.2, 23.3 and 21.3 MPa have been obtained for silicon, silicon dioxide and aluminium respectively. The application of the selective adhesive bonding technique has been successfully demonstrated by encapsulating different types of single crystal silicon inertial sensors.

The control of feature sizes down to the atomic scale made possible with STM based hydrogen lithography allows unprecedented accuracy in the control of the number and distribution of dopant atoms in devices. We present a detailed STM study of the adsorption of PH₃ on STM-patterned H:Si(001) surfaces for the controlled placement of P dopants in Si. In particular we characterise the effect of the orientation of lithographic line features relative to the surface dimer rows on phosphine adsorption and the scaling of dopant density feature size down to single atom lithography.

Piezoelectric micro devices based on lead zirconate titanate (PZT) thin film have received considerable attention because of their wide potential in nanotechnology, biosensors and microelectromechanical systems. Thin film cracking, device short-circuiting and substrate surface degrading are commonly encountered problems for PZT micro device fabrication using chemical solution deposition (or CSD) process. These problems often lead to an extreme low yield (<10%) of fabrication and hinder the integration of piezoelectric components into micro-electromechanical systems. In this work, a new manufacturing method for PZT micro devices is developed for the first time to avoid all these problems. Unlike other modified PZT sol-gel processes, in our process pyrolysised PZT thin film is patterned by wet etching before (rather than after) the high temperature sintering treatment. This new process can tremendously reduce the cracking of thin film and eradicate the diffusion of PZT to those substrate surfaces without Pt buffer layer. The effectiveness of the process is proved by 1) the 100% fabrication yield of a number of PZT micro cantilevers, bridges and platforms, 2) the complete elimination of contaminated surfaces by PZT diffusion.

A problem with micromechanics is that the commonly used fabrication methods and materials are relatively expensive. To be competitive on the market, new low-cost materials and manufacturing methods are necessary. Different micro-devices have already been made, e.g., micropumps. Micro-replication also enables different materials like polymers, metals and ceramics to be used. The research was conducted through part design, mold fabrication, experimental analysis, and quality test. The process parameters including injection speed, melt temperature, mold temperature and packing pressure on quality of micropumps were investigated. The injection molded part was actuated by a piezoelectric disc. Flow test was conducted to check the micropump performance.

A technique is presented for the fabrication of an integrated microfluidic surface acoustic wave (SAW) sensor suitable for a wide range of fluidic analyses. The device was fabricated in Microchem SU8-25, on a PMMA substrate, employing a modified SU8 process. Standard SU8 procedures are sufficiently close to the glass transition temperature for PMMA to cause significant warping. PMMA is advantageous as a substrate material as it is cheap, easily machined, hydrophobic, and exhibits superior adhesion with SU8. A novel die bonding technique was explored to join the SU-8 fluidic structures to a lithium niobate SAW sensor. This involved additional fluidic structures, and the optical adhesive, NOA-73. A device with a 1cm by 1.5cm by 25um chamber was fabricated with these techniques, and was used to explore fundamental properties of flow at the microscale, in particular at the surface of the SAW device.

ABO typing is the first test done on blood that is to be used for transfusion. A person must receive ABO-matched blood, as ABO incompatibility is the major cause of fatal transfusion reactions. Until now, this blood typing has been done manually, and there is therefore a need for an automated typing machine that uses a very small volume of blood. In this paper, we present a new micro blood-typing system with a fully 3-dimentional geometry, which was realized using micro-stereolithography. This system was fabricated with a novel integration process based on a virtual environment and blood typing experiments using this system were successfully performed.

UV Laser micro-machining of metals for the production of micro devices is generating significant interest. This approach to micro-fabrication has the distinct advantage of being non-contact, rapid, flexible and precise. At present, the laser micro-manufacture of new micro device designs, or the introduction of untried materials requires exploration of laser parameters to achieve acceptable yields. We have undertaken a quantitative study of UV laser micro-machining of 2024 Aluminium, Copper and marine grade steel. These metals are of broad application in the manufacture of sensors for structural health monitoring and are of particular interest to defence. The UV laser micro-machining study was carried out using a frequency tripled Nd YAG laser. In this paper the influence of the number of passes of the laser over the metal surface are compared with cutting profiles, and ablation or melt behaviour as a function of cut depth.

In the present work, the authors were focused on control modes used in distributed microsystems. Especially, they studied distributed manipulation like motion active surface that have been an important topic in micro and nanofabrication field. After comparing advantages and drawbacks between centralized, decentralized and distributed control systems, they decided to apply the control mode to an airflow active surface based on pneumatic microactuator array, and fabricated by MEMS technology. The size of the device is about 35x35 mm² for 560 MEMS-based actuators and holes respectively at the front- and the back-side of the silicon substrate. In a first approach, and to overcome fabrication problems of the micro-smart system, combining electronic and electro mechanic elements, a co-design software/hardware solution was implemented. By this way, and using a digital image captured from a CCD camera, autonomy of the distributed microsystems could be developed. Afterward, a feedback control strategy was elaborated by applying principles of autonomous mobile robots that lend it to. A first prototype, validating all control mode principles was successfully implemented directly in software. Experiment results demonstrated advantages and good performances of the method.

Microelectronics for environmental monitoring (microsensors, etc.) present a variety of power supply voltages and operative frequencies from one side and are subject to interference and noise from the external environment on the other. All these aspects lead accuracy and reliability of those circuits devoted to physical measurements a difficult compromise for the designer. Sensors implemented in the newest generation of networks are realized by integrating advanced analog features with digital processing capabilities. The analog blocks, above all, where the processing related to the signal provided by the active element is performed, show in the most substantial way this problem related to EMC inadequacy. In order to restore the top-quality features it is necessary to arrange the best shielding design for the blocks more influenced by interference and noise. So the work of the designer leads to the analysis, simulation and realization of localized and global shields inside and on the packaging. The problem related to the definition of EMC role in designing such shields is very substantial for environmental applications, where performance leads to improve and optimize the traditional designing techniques. The proposal and consequent application of general criteria devoted to define specific needs for shielding is the first step of a logical development oriented to the mature industrial production of efficient and reliable devices able to maintain their performance independently by the influence of external and internal noise.

There has been significant growth in the wireless market where new applications are accompanied with strict design goals such as low cost, low power dissipation and small form factor. Large capacity and range for new applications are the driving force for development of new standard such as third generation mobile system (3G). Recent research results show that the development that was not possible with current IC technology is made possible with MicroElectroMechanical Systems (MEMS) technology. Significant amount of research is taking place to replace the off-chip components with on-chip components to design a high performance receiver front end. The passive components such as switches, capacitors and inductors are integral part of RF front end. High quality (Q) inductors are used to design RF front-end components such as voltage-controlled oscillator (VCO) and low noise amplifier (LNA). However, they are the bottleneck in achieving the on-chip optimum components, because of Q factor dependence on parasitic effects, limiting the performance. In recent research publications different on-chip inductor structures such as coil, polygon, rectangular and stacked configurations have been suggested and used to implement high value of inductance. In this paper design and implementation issues of MEMS inductor are presented. The paper is divided in two sections, the first section presents the role of MEMS based passive components and second section presents design issues, implementation and analysis of different MEMS based inductors.

Numerical simulations are performed to explore the fluid physics of droplet ejection process for a full-size piezoelectric inkjet printhead. In the analysis, the theoretical model takes account of a set of three-dimensional transient conservation equations of mass and momentum, with the incorporation of the continuous surface force model for treating the interfacial surface tension effect. The resultant governing equations are solved using an iterative semi-implicit method for pressure-linked equations consistent (SIMPLEC) algorithm for determining the flow properties. The volume-of-fluid (VOF) method in conjunction with the multi-dimensional piecewise linear interface construction (PLIC) technique is applied to characterize the behavior of liquid surface movement. Using the design configuration of a test piezo-diaphragm printhead, the time evolution of the gas-liquid interface is calculated for a complete ejection cycle of 164 μs. The flow and transport phenomena in various stages, including the ink filling, ejection, and droplet formation, are thoroughly examined in this work.

Nanoimprint Lithography (NIL) is a fast, high resolution replication technology for micromechanics, microbiology and even for microelectronic applications in the sub-100nm range. The technique has been demonstrated to be a very promising next generation technique for large-area structure replication up to wafer-level in the micrometer and nanometer scale. For producing nanometer structures the capital investments required are much lower compared to other next generation methods (e-beam writing, x-ray lithography, EUV lithography, ...). Nanoimprint Lithography is based on two different techniques: Hot Embossing (HE) and UV-Nanoimprint Lithography (UV-NIL). Both methods can be used for replicating dense and isolated features in the range of 70nm to 100μm simultaneously on up to 200mm wafers.

We propose a novel method of fabricating metallic glass thin films using a carousel type sputtering system. In conventional methods of fabricating metallic glass thin films using alloy targets, control of the alloy composition is difficult. However, since r.f. power for each target can be controlled independently in the proposed system, it is easy to control the alloy composition. Thin films of various alloy compositions are fabricated. In this work, near-equiatomic CuZr thin films are fabricated by the sputtering system with rotational speeds of the substrate holder ranging from 10 to 50 rpm. Small-angle XRD revealed that the specimen fabricated with rotation at 10 rpm had a multilayer structure. The specimen fabricated with rotation at 50 rpm exhibited a glass transition temperature of 672 K, a crystallization temperature of 715 K, and a supercooled liquid region of 43 K. However, although the XRD results indicated that the specimen fabricated with rotation at 30 rpm was in an amorphous state, it exhibited solid-state amorphization rather than glass transition before the crystallization in DSC measurement. Thus, the specimen did not become a metallic glass. Clearly, sputtering rate is a very important parameter in the fabrication of metallic glass thin films by the proposed sputtering system. These results have shown the proposed method to be effective in fabricating metallic glass thin films.

A layered Surface Acoustic Wave (SAW) device based on an InO_x/Si₃N₄/36° YX LiTaO₃ structure is investigated for sensing ozone in air at different operating temperatures and concentrations. These concentrations are between 25 ppb and 150 ppb. Layered SAW devices are of a great interest as they show a remarkable performance for liquid and gas sensing applications. This structure is a single delay line SAW device with 64 input and output finger pairs, having periodicity of 24 μm. They were fabricated on a 36° Y-cut X-propagating lithium tantalate (LiTaO₃) piezoelectric substrate. A 1 μm thick silicon nitride (Si₃N₄) layer was deposited over the finger pairs and a 100 nm indium oxide (InO_x) sensing layer was deposited over the Si₃N₄ layer. Both layers were deposited by RF magnetron sputtering. InO_x was chosen as it has a remarkable sensitivity towards ozone. Si₃N₄ was chosen as it is inert and has stable characteristics at high temperature. The sensor performance is analysed in terms of response time, recovery time and response magnitude as a function of operational temperature. The operational temperature ranges between 185°C and 205°C. The sensor shows repeatability, reversibility, fast response and recovery time. At approximately 190°C the highest sensitivity was observed. A frequency shift of 5.0 kHz at 25 ppb, 6.5 kHz at 50 ppb ozone was recorded. The presented results show this structure is promising for gas sensing applications.

A layered Surface Acoustic Wave (SAW) hydrogen gas sensor, based on a delay line structure with 64 finger pairs on input and output port, is fabricated on 64° Y-cut, X-propagating LiNbO₃ substrate. A guiding layer of ZnO is used to increase the sensitivity of the structure. A WO₃ selective layer is employed to H₂ gas sensing applications at different operating temperatures between room temperature and 300°C. In this paper, the fabrication process of WO₃/ZnO/64° YX LiNbO₃ sensor is described and the sensor’s response features are analyzed. The improvement of the response with the addition of a gold catalytic layer on the sensor surface is also investigated.

We present a fabrication method of high aspect ratio 100nm-scale nickel stamper using e-beam writing on the chrome/quartz mask for the injection molding of optical grating patterns. Conventional nickel stamper is fabricated by nickel electroplating process which is followed by photoresist patterning. In the nickel electroplating process, seed layer deposition step is indispensable process. Seed layer of several tens or hundreds nanometer thickness may cause dimension error after fabrication of 100nm-scale nickel stamper. In this paper, we suggest new fabrication process of a 100nm-scale nickel stamper simplified the fabrication process using blank mask. By using chrome layer on blank mask as seed layer of electroplating process, we would like to simplify nickel stamper fabrication process and improve accuracy of the fabricated nickel stamper. Generally, blank mask used in lithography process consists of chrome layer and photoresist layer on quartz substrate. The chrome layer is composed of UV anti-reflection layer of CrON and UV shade layer of Cr(94%Cr-6%C). The UV anti-reflection layer of CrON plays a role of absorption of UV light in UV lithography process in order to prevent interference of incident light and reflection light. Conventional blank mask consists in order of PR, CrON, Cr and Quartz (PR/CrON/Cr/Qz). However, anti-reflection layer of CrON is electrically nonconducting material. Therefore, we have prepared blank mask without anti-reflection layer of CrON in order to use chrome layer as a seed layer of electroplating process. In the PR mold fabrication, we have changed the dosage of electron beam of 9μmC/cm², 8.5μC/cm², and 8μC/cm² to find optimum e-beam dosage for the PR/Cr/Qz blank mask. At the optimum electron beam dosage condition of 8.5μC/cm², PR molds on PR/Cr/Qz blank mask were fabricated within the maximum error of 24nm. The fabricated PR mold shows height of 300±10nm. The electric resistance of Cr layer in the fabricated PR mold of PR/Cr/Qz mask is measured as 100Ω. In the electroplating process, unfortunately, the 75nm-thick Cr layer underneath PR of PR/Cr/Qz mask was damaged due to the high resistance. In this work, we have deposited additional seed layer materials of Ni as thick as 100nm. Finally we got the resistance of 10Ω. Instead of 75nm-thick Cr layer, if we prepare 200nm-thick Cr layer PR/Cr/Qz blank mask, we can carry out electroplating process without additional deposition process of seed layer. After nickel electroplating process, the thickness of the fabricated nickel stamper was approximately 330±20μm. The minimum width of the fabricated nickel line was measured as 116±6nm. Using SPM (scanning probe microscope), we have measured the height of nickel line as 240±20nm. Finally we have fabricated 2.5-AR (Aspect Ratio) nickel stamper with the minimum width of 116±6nm. The fabricated 100nm-scale nickel stamper showed the maximum error of 20nm comparing the PR mold. Consequently, we have optimized electron-beam dosage for the PR/Cr/Qz blank mask and fabricated 100nm-scale nickel stamper of the optical grating patterns with 2.5-aspect ratio.

This paper represents the comparison results of experimental observations and theoretical calculations for splashing in deposition of Copper and Graphite thin films. These films were deposited by Pulsed Laser Deposition (PLD) technique. A Q-Switched Nd:YAG nano-second laser with 1.1 MW power. Thin films and Target surface morphology were studied under the Scanning Electron Microscope (SEM) Splashing was observed only in the copper thin films but not in graphite thin film. Theoretical models also shows the splashing only in copper, not in graphite at 1012 W/cm2 intensity of laser radiation. Because skin depth for copper (of the order of nm) smaller than that of graphite (of the order of μm) for IR radiation. Skin depth is directly related with splashing threshold intensity. Splashing produced that nonuniformity in thin films which reduced application of thin films especially in nano-electronics and smart materials.

A study was preformed to explore the possibility of using Isothermal Solidification technique for sealing medium preparation in wafer level vacuum/hermetic package of MEMS/NEMS devices and to examine the effect of plasma treatment and bonding environment on the shear strength of the sealed structure. Appropriate plasma treatment can improve the bonding strength of the sealing structure and optimized parameters were obtained. The bonding strength of the sample bonded in vacuum environment is larger than in other environments. The hermeticity of the sealed structure was also evaluated. Preliminary results show that the sealed structure can satisfy the hermetic package criterion of MIL STD 883E.

This paper reports on design, fabrication and characterisation of a MEMS-based micro combustor for micro power generation systems. The first micro combustor implemented was a static gas turbine engine. The micro combustor was composed of seven silicon wafers and fabricated using deep reactive ion etching (DRIE). The size of the prototype was 21mmx21mmx4.4 mm. The combustor was assembled, aligned, ignited and tested under a fixture jig. The temperature near the exit of the combustor reached 1550 K, when the mass flow rate and fuel/air equivalence ratio were 0.06 g/sec and 0.8, respectively.

Modal solutions for photonic crystal fibers with circular air holes in a hexagonal matrix are presented, by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, modal hybridness, modal birefringence and group velocity dispersion values have been determined and are shown and discussed.

This paper describes the development of a centerless grinding unit used for precisely processing ferrules, a key component of optical fiber connectors. In conventional processing procedure, the outer diameter of a ferrule is ground by employing a special machine tool, i.e., centerless grinder. However, in the case of processing small amount of ferrules, introducing a centerless grinder leads to high processing cost. Therefore, in order to take measures against this problem, the present authors propose a new centerless grinding technique where a compact centerless grinding unit, which is composed of an ultrasonic elliptic-vibration shoe, a workrest blade, and their respective holders, is installed on a popular surface grinder to perform the centerless grinding operations for outer diameter machining of ferrules. In this work, a unit is designed and constructed, and is installed on a surface grinder equipped with a diamond grinding wheel. Then, the performance of the unit is examined experimentally followed by grinding tests of ferrule’s outer diameter. As a result, the roundness of the ferrule’s outer diameter improved from the original value of around 3μm to the final value of around 0.5 μm, confirming the validity of the new technique.

In this paper, we report a kind of novel belt-like nanostructure of iron silicide, which we call nanobars, synthesized on silicon (001) substrate by microwave plasma method. The iron silicide nanobars were found to be of metallic α-FeSi₂ with tetragonal symmetry (a=b=0.2695nm and c=0.5390nm) by energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. The scanning electron microscope (SEM) morphology indicates that the nanobars, with lengths typically up to several micrometres, widths in the range of 20-200 nm and thickness of 10-100 nm, self-assembly align along <110> directions on (001) silicon substrate and form network structure. The possible self-assembly growth mechanism of iron silicide nanobars was discussed. It is suggested that the optimal matching directions, the reconstruction in high temperature, and the interaction between original depositional iron nanoparticles by the magnetization of microwave magnetic field are the three factors that caused the formation and orientation of iron silicide nanobars. The special structure and self-assembly growth mechanism of iron silicide nanobars might be used in MEMS and NEMS fabricating or self-assembling carbon nanotubes integrated nanocircuits from the bottom up.

Recently, many efforts have been made to improve the device performance of nanocrystal memory by replacing the SiO₂ with various high dielectric constant (high-k) materials, especially embedded with Ge nanocrystals. This paper demonstrates the floating gate memory effect by embedding nanometer-sized Ge nanocrystals in hafnium aluminate (HfAlO) high-k gate dielectric. A 5 nm-thick amorphous thin film of HfAlO was first deposited on (100) p-Si substrates as a tunneling gate oxide layer by laser molecular beam epitaxy deposition using a HfO₂ and Al₂O₃ composite target. Well-defined (~10 nm in diameter) nanometer-sized Ge dots were subsequently deposited on this thin tunneling gate oxide followed by a 30 nm-thick top control gate oxide of HfAlO. Transmission electron microscopy has been carried out for a detailed study of structural properties of the Ge nanocrystals embedded in the HfAlO films, and their relationships to electrical properties. Electrical properties have been characterized by means of high-frequency capacitance-voltage (C-V) and current-voltage (I-V) measurements on the metal-oxide-semiconductor capacitors. A counter-clockwise hysteresis C-V loop has been obtained and a threshold voltage shift of 1.0 V has been achieved indicating stored electrons (up to a density of 2x10¹² cm^-2) in the Ge-nanodots floating gate and thus the memory effect. Time-dependent I-V measurement also showed low leakage current of floating gate system. These results suggest that the Ge nanocrystals embedded in HfAlO are promising for floating gate memory device application.

A laser-induced plasma in laser-material interaction due to the fact that it is in an extreme state of high-energy concentration is shown to be a powerful tool to perform drilling process to create micro channels in bulk quartz substrates under certain conditions. The plasma was induced by a Q-Switched Nd:YAG laser incident to a quartz substrate after pre-damaged by thermal-induced processing. The channels are of high quality with smooth kerf surface and the dimension of channels can be controlled from around 25 to 140 microns by a software program that interfaces with the laser system. A study of the dependence of drilling rate on the depth of channels provides a straightforward method for controlling the formation of plasma. The process technology, process characterization, and initial test results of the fabricated micro channels are presented in this paper.

Although sub-micron structures have been fabricated with ion beam lithography using focused MeV ions, the best resolution of the method has not yet been approached. The best resolution is potentially around 10 nm which is the diameter of latent damage produced by the passage of a single fast ion through sensitive materials where the ion range could be tens of micrometres. In principle, the latent damage can be developed to create very high aspect ratio nanostructures. We call this technique single ion nanolithography. In order to approach the ultimate resolution of lithography with single ions we investigate the resist material, the exposure as a function of ion type and development parameters. To implement the technique we have developed a novel strategy that employs a resist film on an active substrate that functions as a detector sensitive to single ion impacts. Together with a focused microbeam, the precise control of ion fluence attained by counting ion impacts allows us to perform a convenient systematic study of the track formation and seek conditions where single ion tracks can be produced. We report here the current status of the investigations using PMMA and CR-39 resists which are shown to be sensitive to single ions. A key issue is also the post-development imaging method.

The design, simulation, modeling and characterization of low-temperature co-fired ceramics (LTCC) RF switch module for GSM band applications were investigated. RF switch circuits were simulated by ADS tool, manufactured using a LTCC multi-layer in the GSM band. It was integrated with low pass filter on switch module. Insertion and return losses at 900 MHz of the low pass filters were designed to lower than 0.3 db and higher than 12.7 db respectively. The RF switch module was constructed, containing 10 embedded passives and 3 surface mounted components integrated on 4.6×4.8×1.2 mm³ volume, 6-layer integrated circuit. The insertion loss of switch module at 900 MHz was about 11~19 db.

In this study, spiral inductors on the SiO₂/Si(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of 0.7~2.0 μm was deposited on the substrate. Square inductors were fabricated through the wet chemical etching technique. The inductors are completely specified by the number of turns, coil width and the coil spacing. Both the width and spacing were varied from 10 to 50 μm and from 20 to 70 μm, respectively. The Frequency dependency of inductance and Q factor were investigated to analyze the performance of spiral inductors.

Optical tweezers (OT) uses a focused laser beam to trap and move microscopic objects. The design of OT consists of laying out stationary and moving (or rotating) lenses and mirrors so that two design constraints are met at the objective back aperture (OBA): 1) the laser beam has to be pivoted around the center, and 2) the beam has to keep the same degree of overfilling. While these constraints are met, the objectives are to maximize the divergence/convergence angle and the beam rotation angle at the OBA. They are each accomplished by moving a lens or rotating a mirror, respectively. There are few known designs that give (claimed) good performances while satisfying above constraints. However, these designs are improvised inventions with no attempts in optimization. In this paper, we propose a new method for designing an optimized OT that achieves the best performance with given pool of optical elements. Our method, (Topology Optimization of the Optical Tweezers Setup) first divides the layout space into finite lattices and then distributes lenses and mirrors to appropriate lattices. Subsequently, whether the attempted configuration conforms to the constraints is tested. If the test is successful, the layout and its performance are recorded. At the end, the best performing layout is found. In this paper, we primarily concentrate on optimizing the positions of lens components. In the future, this approach will be generalized for more complicated configurations that include mirror components.

The paper describes about a useful study on the deformed shapes of microstructures fabricated by PCT (Plane-pattern to Cross-section Transfer) Technique. Previously, we have introduced the PCT technique as an additional process to conventional X-ray lithography for an extension of 2.5-dimensional structure to 3-dimensional structure. The PMMA (poly-methylmethacrylate) has been used as the X-ray resist. So far, microneedle and microlens arrays have been successfully fabricated in various shapes and dimensions. The production cost of X-ray mask has been known as the most expensive process for LIGA step, therefore, to predict the resulting shapes of structure precisely before fabricating the mask is relatively important. Although, the 2-D pattern on the X-ray mask can form a similar shape resulting in 3-D structure, the distorted shapes of microstructures have been observed. A linear-edged pattern on the X-ray mask resulted as an exponential-edged structure and an exponential-edged pattern resulted as an exceeding curvature, for example. This problem causes a change in the functional property of the array. In the case of our microneedle array, the linear-edge is highly required since it increases the strength of microneedle. We have investigated and suggested a calculation method fir a shape-prediction of microstructure fabricated by PCT technique in this work. The compensation calculation by our theories for an X-ray mask design can solve the undesired shape resulting after X-ray exposure. Moreover, the dosage control and suitable developing time are given in order to see through the current condition of the currently used synchrotron radiation light-source.

We present a novel technology for a cyclo-olefin-copolymer (COC) plastic microfluidic platform for heat control with fully semiconductor process-compatible photolithographic 5 μm-wide metal patterns, for heaters, electrodes, and temperature sensors and a thin membrane structure. Through tests of compatibility of some thermoplastic materials with chemical solutions and temperature tolerance to the semiconductor processes (thin film depositions, photolithography, and etchings), we selected COC as a semiconductor process-compatible plastic material for biomedical applications. For photolithography processes, we manufactured the 5’ COC wafer with flat surface with c.a. 3 nm surface roughness, employing a novel flame-torched injection-molding method. Furthermore, the part of heating blocks on COC wafers is controlled thickness to the 100 μm, to enhance the heat-ramping speeds through reduction of the thermal mass. In order to fabricate the Au thin film micro-patterns for temperature sensors, heaters, and electrodes, Au film (100 nm) was deposited by e-beam evaporator and patterned by using standard photolithography, and wet-etched. The micro-patterned Au temperature sensors, heaters, and electrodes was demonstrated. For insulating layers, Al₂O₃ film was deposited by an ALD system, patterned by using the standard photolithography, and wet-etched. Using the COC microfluidic platform, we tested thermal cycling with simple heating and natural cooling on chip with water and, heating rates (5°C/s when heating, 3°C/s when cooling) are obtained. Therefore, the COC microfluidic platform can be applied to a DNA lab-on-a-chip.

To evaluate mechanical properties of the precision component after joining, nickel base superalloy was welded while subjected to synchronous mechanical vibration. In the vibrated specimen, the weld metal was seen to have fine microstructures, and low residual stress levels were measured in specimens subjected to vibration. Thus, it is believed that the mechanical properties of this vibrated weldment are improved. However, the hardness, strength, and ductility of the weld were compromised when vibration was applied. It was found that cyclic stress plays a role in relieving residual stress, in reducing hardness, and in worsening the mechanical properties.

Rare earth substituted piezoelectric ceramics with the composition Pb_xRE_yTi_0.98Mn_0.02O₃, with RE = Pr, Pr+Eu, Gd+Nd, and a few percent of bismuth to partially substitute the lead, have been prepared by solid state reaction of oxide powders. Structural and morphological investigations were performed on the poled samples. The uses of high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) have shown the domain structure and the formation of the tetragonal perovskite phase. A non-destructive analysis of the elemental distribution on the surface of the samples has been performed by the electron probe microanalyzer. Samples with diameter 10mm and thickness 1mm have been employed for electrical characterization. Material coefficients have been investigated as a function of temperature. The dielectric permittivity and resistivity were measured for wide temperature and frequency ranges. The Gd+Nd doped PT material has been used to realize a SAW transducer.

It has been shown recently that it is possible to reverse-engineer the folding of complex proteins by an AFM-based force versus distance methodology. In essence, the protein is attached to a functionalised surface, then linked to a functionalized tip of a force-sensing/imposing lever, and finally stretched by withdrawal of the probe. The experiments are technically demanding, and subject to a number of artefacts. Moreover, the unfolding process cannot readily be reversed. A 'reverse’ methodology is possible in principle and is likely to provide greater insight into the folding/unfolding sequence. The protein in question will now be attached to a functionalized superparamagnetic bead in solution. A functionalized probe is then introduced into solution whereupon the protein (and its bead) attaches itself to the tip of the probe, while being tracked optically. The system is then submerged in an inhomogeneous magnetic dipole field, giving rise to a magnetic dipole-dipole interaction with the bead. The resultant force will stretch the protein, while being monitored at a force resolution of ca. 1 pN by the deflection of the lever. The significant aspect of the scheme is that the probe acts as a position-sensitive element as well as being a force-sensing device. The field gradient and its rate of change within the interaction volume can readily be controlled to 1 part in 10⁶, and can be reversed. Thus the unfolding/folding sequence can be retraced for the same molecule. Moreover, information about kinetics will be accessible from varying the rate of change in field strength, and the effects of ambient fluid conditions can be investigated in real time with a flow-through arrangement. The proposed methodology is likely to be more userfriendly as a result of dispensing with the functionalized surface, and by being able to determine optically that a single functionalized bead has arrived at the probe tip. Elements of the experimental arrangement are currently at the design stage.

Oxidative nano-writing by a conducting AFM tip to Si substrates has so far been ascribed to an anodic electrochemical process. However, there is evidence that thermal effects may play a role. More recently it has been demonstrated that conducting diamond-like carbon (DLC) films can be nano-machined by a biased conducting tip; the process is evidently due to local thermally activated oxidation and formation of CO₂. Thus the prevailing description in terms of an athermal anodic oxidative mechanism will need to be revisited and possibly revised. The physico-chemical state of the tip is known to affect the rate and efficiency of the process in some unspecified manner. It is plausible to ascribe variations in the I-V characteristics and thermal transport to tip effects that are operational at the point of contact. However, so far the focus has been on the surface, and little attention has been given to a detailed and relevant characterization of the tip and its efficacy as a manipulative probe. Tips were prepared with a range of known initial conditions (i.e. doped Si plus H-termination, Au-coating, or native oxide). I-V characteristics were correlated against oxidative efficiency versus clean H-terminated Si, Si plus native oxide, Si plus 2.5 nm thermal oxide and DLC. The outcomes at positive sample bias can variously be described by ohmic transport, by Fowler-Nordheim, and direct tunnelling. Likewise, tip alteration resulting from oxidative surface manipulation has been monitored by subsequent characterization. The evidence favours a thermal mechanism of oxidation arising from a repetitive, but interrupted, deposition of thermal energy at the tip-to-surface junction, where inelastic tunnelling completes the circuit. Thus there is a narrow temperature window of optimum conditions. The tip will deteriorate irreversibly if the peak temperature is too high, while oxidation of the surface will not take place if the peak temperature is too low.

Silicone rubbers have steadily gained importance in industry since their introduction in the 1960’s. Poly(dimethylsiloxane) (PDMS) is a relatively soft and optically clear, two-part elastomer with interesting and, more importantly, useful physical and electrical properties. Some of its common applications include protective coatings (e.g., against moisture, environmental attack, mechanical and thermal shock and vibrations), and encapsulation (e.g., amplifiers, inductive coils, connectors and circuit boards). The polymer has attracted recent interest for applications in soft lithography. The polymer is now routinely used as a patterned micro-stamp for chemical modification of surfaces, in particular Au substrates. Prominent stick-slip effects, surface relaxation and elastic recovery were found to be associated with micro/nano manipulation of the polymer by an AFM-based contact mode methodology. Those effects provide the means to explore in detail the meso-scale tip-to-surface interactions between a tip and a soft surface. The dependence of scan speed, loading force, attack angle and number of scan lines have been investigated.

The publication in 1994 of Shor's algorithm, which allows factorization of composite number N in a time polynomial in its binary length L has been the primary catalyst for the race to construct a functional quantum computer. However, it seems clear that any practical system that may be developed will not be able to perform completely error free quantum gate operations or shield even idle qubits from inevitable error effects. Hence, the practicality of quantum algorithms needs to be investigated to estimate what demands must be made of quantum error correction (QEC). Several different quantum circuits implementing the quantum period finding (QPF) subroutine, which lies at the heart of Shor's algorithm have been designed, but each tacitly assumes that arbitrary pairs of qubits can be interacted. While some architectures posses this property, many promising proposals are best suited to realizing a single line of qubits with nearest neighbor interactions only. This paper will present a circuit suitable for implementing the QPF subroutine for such linear nearest neighbor (LNN) designs. We will then present direct simulation results showing for both the LNN circuit and for a circuit utilizing arbitrary interactions, that the QPF subroutine is very sensitive to a small number of errors in the entire circuit. These results can then be used to briefly examine some of the practical issues to implementing such large scale quantum algorithms.

We examine exchange coupling in the Kate quantum computer, which consists of isolated spin-1/2 ³¹P donors in a pure Si lattice. A calculation is made using full configuration interaction, a reasonably large basis set, and a simple physical model. Basis set convergence was not obtained, and increasing the size of the matrix further appears to be computationally impractical. We therefore consider a Gaussian basis set approach. A brief description of the McMurchie-Davidson algorithm for the expansion of SGTF functions into Hermite polynomials is given. We also give the results of a single-donor computation in this basis.

Quantum-dot Cellular Automata (QDCA) provide an interesting experimental system with which to study the interaction of a charge-based two-level system with the surrounding solid-state environment. This is particularly important given the recent interest in solid-state quantum computers using charge-qubits. We show that many of the properties of these qubits, coupling strength, tunnelling time, relaxation rate and dephasing time can be estimated using a QDCA cell like structure. Calculations are performed for the case of buried donors in silicon but the results are equally applicable to other forms of charge-qubit.

Direct single-spin detection for read-out in solid-state quantum computing architectures is a difficult problem due to the isolation of the spin qubit from its environment. Converting the problem to one of charge measurement is advantageous as we can measure the charge qubit using a single electron transistor (SET). The read-out state for the standard Si:P architecture -- a doubly occupied donor state D^- -- results from spin-dependent electron tunneling between donors. Complications arise due to the low binding energy of this state, meaning existing adiabatic transfer schemes may cause ionisation of the D^- state before measurement can be performed by the SET. We describe a new method for the read-out of spin qubits, using gated electric fields at resonance with the transition being measured, to resonantly transfer a single electron to the SET using small DC fields. In addition to this we propose an extension to this method where a far-infrared laser (FIR) induces the resonant transfer.

The feasibility of a charge based solid state quantum computing depends to a great extent on the ability to overcome the presence of noise sources such as Johnson noise in the gates and charge traps due to defects in the material. In this paper, we study the effects of dephasing from charge traps for the Si:P charge qubit.

Single electron transistors (SET) are devices that can be used as highly sensitive electrometers, with sensitivities approaching the quantum noise level. They can be used as measurement devices for quantum systems, including quantum computers and quantum-dot cellular automata, and as logic elements in their own right as replacements for MOSFETs. For solid-state quantum computing applications it is vital to maximize the charge sensitivity to decrease readout time and increase readout fidelity. We analyze the interactions between a SET and a double dot system. The SET sensitivity is described in terms of the current variation through the SET due to a single electron's location on the two dots. We use finite element modeling to determine the capacitive coupling between all objects in our system, which in turn allows us to determine the current in the SET based on steady-state energy minimization arguments. We base our geometries on experiments involving a twin-SET device developed as a prototype for solid-state quantum computing read-out. Our model allows us to systematically vary the device geometry in order to optimize the sensitivity of the SET.

A series of new organic dye-interleaved nanocomposites (NCs) were prepared by intercalation of alizarin-3-sulfonate anion (Az3S) into Zn-Al-layered double hydroxide (LDH) inorganic lamella host at different concentrations via self-assembly method. The physicochemical properties of the as-synthesized LDH and NCs were studied using PXRD, FTIR, ICP-AES, CHNS, true density and SEM techniques. Basal spacing expansions from 9.0 Å in LDH to about 10.0 and 20.0 Å in the resulting NCs were observed, suggesting that Az3S was probably orientating itself in two or more different ways in the host-matrix due to two different species that co-existed in the mother liquor during the synthesis. FTIR study on NCs further confirmed the interleaving by showing combined patterns of LDH and Az3S. Changes in chemical composition in NC, particularly the increase in carbon and sulfur content compared to the LDH were in strong agreement with the PXRD and FTIR studies. In addition, the inclusion of an organic moiety as interleaving guest in NCs was found to reduce the true density and significantly alter the microscopic surface morphology of the resulting NCs.

We construct fault-tolerant approximations of rotation gates required by Shor's algorithm using only fault-tolerant gates that can be applied to the 7-qubit Steane code. A general scaling law of how rapidly these fault-tolerant approximations converge to arbitrary single-qubit gates is also determined.

Tantalum oxide added MgCuZn ferrite powders were synthesized by a co-precipitation method using a microwave-hydrothermal (M-H) method. The phase identification of the prepared samples was characterized by X-ray diffraction and crystal size and morphology were determined by transmission electron microscopy (TEM). Nano-phase ferrites with high surface area were synthesized at 160°C after a treatment time of 1 hour. M-H synthesized powders were conventionally fired at a temperature of 900°C/4hrs. The variations of the sintered density, initial permeability and electrical resistivity as a function of additive concentration at room temperature have been investigated. The multi-layer chip inductors were fabricated using prepared ferrites. The prepared inductors posses better electrical properties than of multi-layer chip inductors prepared using the NiCuZn ferrites.

Heavy metal fluoride glasses have many photonic applications because of their wide spectral window and lasing properties when doped with rare earths. Before fluorozirconate glasses were discovered almost all known glasses were oxide based and glass formation in fluoride compositions was not predicted. The usual theoretical approach considers the thermodynamics of solidification from the melt. The theory presented here assumes that almost any material can be solidified as a glass if cooled fast enough and considers conditions necessary to devitrify the glass formed. Nucleation and crystal growth parameters can be defined which depend only on the composition of the glass and the thermodynamic and atomic properties of the constituents and which are independent of time and thermal history of the glass. These give a quantitative expression corresponding to experimental glass-stability which can be used to plot the entire glass forming phase diagram of any fluoride system. The theoretical glass-forming phase diagrams closely match the experimental diagrams. The nucleation and crystal growth parameters can be used to define glass-forming limits which are universal for all glasses, whether fluoride, chalcogenide, oxide, nitride or even metallic glasses. Silica is confirmed as the most stable of all possible glasses.

The biology and semiconductor technology have progressed independently. There was a large distance between them and a substantial interdisciplinary research area was left untouched. Recently, this situation is changing. Some researchers are stimulating semiconductor technology to introduce bio-molecules into the nano-fabrication process. We proposed a new process for fabricating functional nano-structure on a solid surface using protein supramolecules, which is named “Bio Nano Process” (BNP). We employed a cage-shaped protein, apoferritin and synthesized several kinds of nanoparticles (NP) in the apoferritin cavity. A two-dimensional array of them was made on the silicon wafer and this array was heat treated or UV/ozone treated. These processes produced a two-dimensional inorganic NP array on the silicon surface. The size of NP is small enough as quantum dots and the floating nanodots memory using this NP array is now under development. We also proposed another process using the obtained nanodot array as the nanometric etching mask. This was realized by the neutral beam etching and 7nm Si nano columns with high aspect ratio were fabricated. These experimental results demonstrated that the BNP can fabricate the inorganic nanostructure using protein supramolecules and the BNP opened up a biological path to nanoelectronics devices.