We present a combined analysis on the creation and fabrication of three-dimensional bicontinuous photonic crystals with large complete gaps based on the modulation of the dielectric material along principal directions and its relation to the interference lithography technique.

Lithography and the processes associated with it are the backbone of the nanotechnology revolution. Several developments are occurring simultaneously: a drive to reduce minimum feature size leading to advances in microelectronics, the use of lithographically patterned structures to prepare devices for photonics, biotechnology and other forms of nanotechnology and finally the drive to create three-dimensional (3D) structures for device and new materials creation. Thus the controlled formation of nanometer scale structures in two and three dimensions is of increasing interest in many applications. This paper will overview new approaches for the construction of small-scale structures using methods generally considered as next generation lithography. New approaches derived from two photon processes for the formation of complex images and the development of patterned structures will be described. Finally in the production of 3D patterns, the possible role of self-assembly coupled to lithography will be examined. Photodefinable block copolymers with erodable microstructures have been successfully used to form mesoporous materials and will be discussed.

EUV lithography is one of the most promising technologies for the delineation of 45-nm half-pitch patterns (hp 45 on the ITRS Roadmap) and below. However, many problems remain to be solved before it can be considered a practical tool. The light source is the most critical issue for obtaining a reasonable throughput, and the next is the fabrication of defect-free multilayer mask blanks. The construction of an aspherical optical system is also a key issue. From an economic standpoint, cost is a crucial concern regarding use of this technology in an industrial environment. In Japan, four consortia are working on the development of EUV lithography: EUVA is investigating the source and the system, including the metrology of an aspherical optical system; the Leading Project is working on the basic technology for a laser-produced plasma source; ASET is developing multilayer masks and resist process technology; and MIRAI is researching actinic defect detection for multilayer mask blanks. This paper describes the recent activities of these consortia and the future plans for EUVL development in Japan.

In recent years, the chemistry of DNA has expanded from biological systems to nanotechnology. The generalization of the biological processes of reciprocal exchange leads to stable branched motifs that can be used for the construction of DNA-based geometrical and topological objects, arrays and nanomechanical devices. The information in DNA is the basis of life, but it can also be used to control the physical states of a variety of systems, leading ultimately to nanorobotics; these devices include shape-changing, walking and translating machines. We expect ultimately to be able to use the dynamic information-based architectural properties of nucleic acids to be the basis for advanced materials with applications from nanoelectronics to biomedical devices on the nanometer scale.

The hybridization specificity of DNA allows the design of sets of oligomers which, when mixed together, self-assemble into complex nanoscale structures. Such structures can be induced to undergo configuration changes by incorporating motor domains consisting of regions of single-stranded DNA to which complementary "fuel" strands can hybridize. The principles of operation of these devices and prospects for making free-running DNA-based molecular motors are described. Potential applications for these devices, including the construction of materials whose mechanical properties can be altered in the response to the presence of specific oligomers, will be described.

Plasma etching is an enabling technology to pattern novel materials and to generate small structures. This paper provides a plasma etching perspective in the era of nanofabrication, using the definition of the gate structure of a metal-oxide-semiconductor field effect transistor (MOSFET) as an example, followed by the importance of predictive modeling, and finally the application challenges of plasma etching in fabricating micro-chemical and biological sensors.

Lithographic control over nanostructures has recently evolved to an accuracy that permits the sub-wavelength manipulation of light within high refractive index semiconductors. We have used this lithographic control to fabricate two-dimensional photonic crystal cavities and micro-ring resonators. Here we will show the fabrication techniques utilized for the construction of High-Q nanocavities and, in particular, focus on the influence of present-day lithographic and etching procedures on the performance of the cavities. Applications of these optical cavities range from communications to chemical sensing and we will describe the effects of geometry on the different applications. We show the use of optical cavities for the miniaturization of optical spectroscopy systems with ultra-high spatial and spectral resolution.

We developed a nano-manufacturing platform based on wafer level nano-replication with mold and nano-pattern transfer by nano-lithography. The nano-replication process, which based on imprinting a single-layer spin-coated UV curable resist, achieved excellent nano-patterning fidelity and on-wafer uniformity with high-throughput. Nano-optic devices, such as, quarter wave plates and polarizers, were manufactured with the nano-manufacturing platform. Excellent wafer level performance and yield were achieved. The developed technology is suitable for high-throughput and low cost manufacturing needs for commercializing nano-structure based optical devices and integrated optical devices.

Electron beam lithography has been used to demonstrate square and hexagonal close packed two-dimensional arrays of gold particles formed on transparent substrates for Surface Enhanced Raman Scattering (SERS) spectroscopic analysis of optically trapped single spore biological agents. Thin chromium or titanium films have been demonstrated to provide a sufficiently reflective surface to enable the controllable patterning of features as small as 30nm, or inter-particle spacings as small as 50nm, while retaining transmission in the visible to infrared spectral region. These substrates have been successfully used in a SERS/optical tweezer configuration, in which polystyrene particles and pyridine molecules in aqueous solution have been trapped, and their SERS-active spectra demonstrated. The technique described in this work for nanoscale features patterned on transparent substrates holds promise for inexpensive, nanotechnology-enabled chemical/biological sensor applications.

Relative surface topography of metal electrodes is one of the subtle issues determining the electrical performance of molecular devices. Systematic conductivity measurements of nanoscale junctions containing self-assembled monolayer of conjugated molecules are reported for a variety of metal electrodes. The monolayer is assembled on 25-100 nm electrode. Another 10-100 nm electrode is defined on top of the monolayer by metal evaporation. The characteristic energy scales are determined from the temperature dependence of conductance and from the non-linear current-voltage characteristics. Unexpectedly, the energy scales of the dominant conductance channels are small in comparison with the molecular level spacing. In all cases, the dominant room temperature conductance is hopping with characteristic energy of the order of 10-100 meV determined by the nature of metal contacts. Relative contribution of tunneling conductance strongly depends on the surface topography of the metal electrodes.

The interest in organic based molecular electronics has spurred new attempts to control electronic properties of single molecules. We are approaching this goal by looking at two systems: conductivity of thiol-based self-assembled monolayers (SAMs) and phenylene ethynylene oligomers deposited on Au surfaces, and viability of covalently tethering molecules to Si substrates. In both cases, the molecules have extended conjugated π-systems. In this report, we will present results of scanning tunneling microscope investigation of oligo (phenylene ethynylene)(OPE) inserted between molecules of monolayers of dodecanethiol self-assembled on Au(111)/mica substrates, and XPS results of phenylacetylene and 1-bromo-2-ethynylbenzene attached to Si (111) substrates. The investigated OPE are both unsubstituted and substituted with a single -NO₂ group on the central ring [4,4’-(diethynylphenyl)-2’-nitro-1-benzenethiolate] inserted in the defects of dodecanethiol SAMs. The conductivity of those systems attached to Au varies as a function of time. Our results show no particular dependence of this variable conductivity on substitution and structure of the monolayer. In addition, preliminary experiments have been performed attaching phenylacetylene and 1-bromo-2-ethynylenebenzene to variously doped hydrogen terminated Si(111) surfaces in-situ using UV photon assisted propagation reactions. The object is to determine how the conductivity through the molecules depends upon the relative alignment of the substrate conduction and valence bands and the molecular bonding and antibonding levels.

The so-called electrostatic layer-by-layer self-assembly method permits to immobilize various functional modules into layered thin film architectures. Adsorption rests primarily on electrostatic interactions of oppositely charged species. Here, we show that immobilization of functional components, such as polyoxometalates (POM), enzymes, or dyes into such multilayers results in layers with interesting properties and devices, including electrochromic windows or sensors. Using this approach it is possible to interface cytochrome c to a surface. The resulting multilayers are electroactive and are interesting model systems to study redox processes and bioelectronic devices. Through the design of the multilayer it is possible to construct materials with polarity gradients capable of vectorial electron transport needed for artificial photosynthesis.

Layer-by-layer (LbL) nanoassembly in combination with traditional lithography and microfluidics was applied for the fabrication of ultrathin microcantilevers and for the modification of microchannel surface. Hundreds of cantilevers were fabricated on a silicon wafer simultaneously. The purpose is to develop chemical/biosensor arrays for parallel, massive data gathering. Microcantilever optical deflections were measured using a four-quadrant AFM head with integrated laser and position sensitive detector. In the second part, laminar flow fabrication of interpolyelectrolyte complexes was studied inside a microchannel. Polyelectrolyte micropatterns were studied using fluorescent confocal microscopy. Filament like, 15 μm, interpolyelectrolyte microstripes were formed at flow rate higher than 0.01 mL•min^-1 and concentrations of the initial polyelectrolytes below 1 mg•mL^-1. New, soft micropatterning technique for the anisotropic modification of polyelectrolyte nanocapsules was also demonstrated. The microchannel surface was made sensitive to pH by coating the surface of the channel with a pH sensitive dye using LbL assembly to control the reaction.

Aluminum silicate nanoaggregates grown at near-room temperature on an organic template under a variety of experimental conditions have been imaged by transmission electron microscopy. Images have been automatically classified by an algorithm based on “spectrum enhancement”, multivariate statistics and supervised optimization. Spectrum enhancement consists of subtracting, in the log scale, a known function of wavenumber from the angle averaged power spectral density of the image. Enhanced spectra of each image, after polynomial interpolation, have been regarded as morphological descriptors and as such submitted to principal components analysis nested with a multiobjective parameter optimization algorithm. The latter has maximized pairwise discrimination between classes of materials. The role of the organic template and of a reaction parameter on aggregate morphology has been assessed at two magnification scales. Classification results have also been related to crystal structure data derived from selected area electron diffraction patterns.

The use of virus nanoparticles, specifically Chilo and Wiseana Invertebrate Iridovirus, as building blocks for iridescent nanoparticle assemblies and core substrates in the fabrication of metallodielectric nanostructures is discussed. Virus particles are assembled in vitro, yielding films and monoliths with optical iridescence arising from multiple Bragg scattering from close packed crystalline structures of the iridovirus. Bulk viral assemblies are prepared by centrifugation followed by the addition of glutaraldehyde, a cross-linking agent. Long range assemblies were prepared by employing a cell design that forced virus assembly within a confined geometry followed by cross-linking. In addition to these assemblies core-shell particles were created from the same virus. A gold shell is assembled around the viral core by attaching small gold nanoparticles to the virus surface by means of the inherent chemical functionality found within the protein cage structure of the viral capsid. These gold nanoparticles act as nucleation sites for electroless deposition of gold ions from solution. UV/Vis spectroscopy and electron microscopy, were used to verify the creation of the virus assemblages. The optical extinction spectra of the metallo-viral complex were compared to Mie scattering theory and found to be in quantitative agreement. These investigations demonstrate that direct harvesting of biological structures, rather than biochemical modification of protein sequences, is a viable route to create unique, optically active materials.

In order to develop ultra-low-k interlayer dielectric films for ULSIs in 45 nm technology generation, a self-assembly technology was introduced to form porous silica films. The precursor solution for the self-assembly contained cationic surfactant such as alkyltrimethylammonium chloride (ATMACl) and TEOS in ethanol diluted with water. It was spin-coated on a Si wafer so that 2-dimentional hexagonal configuration of self-assembled cylindrical micelles was formed on the wafer, resulting in formation of the 2-dimensional hexagonal structure of the cylindrical tubes of silica after calcination. The pore diameter and the resulting dielectric constant can be controlled by the number of carbon atoms in the alkyl chain of ATMACl surfactant. A nonionic surfactant such as polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO triblock copolymer was also used to form disordered porous silica as well as periodic porous silica films. The mechanical properties of the self-assembled porous silica film were reinforced without changing the dielectric constant by introducing tetramethyl-cyclo-tetra-siloxane (TMCTS) treatment. Significant enhancement of elastic modulus (E) and hardness (H) was achieved by TMCTS treatment at 350°C. The effect of TMCTS treatment on the reinforcement of disordered porous silica was demonstrated. Another important property of porous low-k film is adhesion. TMCTS treatment increased the adhesion of the porous low-k silica film at the Si interface significantly. High modulus porous silica films were formed and E of 8 GPa and k of 2.07 were achieved simultaneously. Cu/low-k damascene structure for 45-nm BEOL technology was demonstrated successfully.

Zinc oxide (ZnO) is a technologically important material because of its multi-functional properties, with applications ranging from piezoelectric transducers and varistors to wide-bandgap semiconductor for UV emitters and detectors. In addition to polycrystalline ceramic powders and epitaxial thin films, recent advances in ZnO have been in vapor and solution phase growth of complex nanostructures. For these nanostructures to be useful, a means to place them strategically on the surface is needed. Here we will describe using micro-contact printing to pattern self-assembled monolayer (SAM) molecules that locally inhibit crystal growth on surfaces. These chemically patterned surfaces are then used as templates for ZnO nanorod growth in aqueous solutions. We demonstrate good control of crystal placement with feature size down to 1 µm. In addition, we find that restricting active nucleation regions results in a marked increase in nucleation density. These results are the first demonstration of combining soft lithography and bio-inspired crystal growth to make nanostructures of ZnO. The success illustrated here indicates that such a combination may be applicable to a much broader range of materials systems than previously envisioned.

We report the catalyst-free growth of ZnO nanotips by metalorganic chemical vapor deposition (MOCVD) on various substrates, including c-sapphire, (100) Si, titanium, glass and SiO₂. Structural, optical, and electrical properties of ZnO nanotips are investigated. ZnO nanotips are found to be single crystalline and oriented along the c-axis normal to the growth plane. The nanotips exhibit dominant free excitonic transition and enhanced luminescence efficiency with negligible deep-level emission. Controllable in situ Ga doping during MOCVD growth reduces the resistivity of ZnO nanotips. Selective growth of ZnO nanotips has been achieved on patterned Ti/r-Al₂O₃, SiO₂/r-Al₂O₃, and silicon-on-sapphire (SOS) substrates. It provides the potential to integrate ZnO nanotips and ZnO epitaxial films on a single patterned substrate for various device applications.

Characteristics of photosensitive low-k methylsilsesquioxane (MSQ) were investigated by use of electron-beam lithography. Photosensitive low-k MSQ makes it possible to realize via and trench patterns for Cu damascene technology in the ultra-large-scale-integrated (ULSI) circuit multilevel interconnect integration without dryetching processes. In this paper the dependences of exposure dose, humidification treatment and development method on critical dimension were investigated. It is found that longer humidification treatment resulted in the lower critical exposure dose, while the feature sizes were enlarged. The feature sizes had a linear correlation with exposure dose. Then reduction of the critical exposure dose minimizes the feature sizes. The development with ultrasonic wave was developed to reduce the critical exposure dose for 100 nm line and space pattern with the aspect ratio 3.3.

Electronic detection of biomolecules is gradually emerging as effective alternative of optical detection methods. We describe transistor devices with carbon nanotube conducting channels that have been used for biosensing and detection. Both single channel field effect transistors and devices with network conducting channels have been fabricated and their electronic characteristics examined. Device operation in (conducting) buffer and in a dry environment - after buffer removal - is also discussed. The devices readily respond to changes in the environment, such effects have been examined using gas molecules and coating layers with specific properties. Finally the interaction between devices and biomolecules will be summarized. The application of devices for detecting biological processes and bio-electronic integration is described in the paper 5593-07.

We report our fabrication of nanoscale devices using electron beam and nanoimprint lithography (NIL). We focus our study in the emerging fields of NIL, nanophotonics and nanobiotechnology and give a few examples as to how these nanodevices may be applied toward genomic and proteomic applications for molecular analysis. The examples include reverse NIL-fabricated nanofluidic channels for DNA stretching, nanoscale molecular traps constructed from dielectric constrictions for DNA or protein focusing by dielectrophoresis, multi-layer nanoburger and nanoburger multiplets for optimized surface-plasma enhanced Raman scattering for protein detection, and biomolecular motor-based nanosystems. The development of advanced nanopatterning techniques promises reliable and high-throughput manufacturing of nanodevices which could impact significantly on the areas of genomics, proteomics, drug discovery and molecular clinical diagnostics.

We present, along with theoretical scaling arguments, measurements of the equilibrium and dynamic properties of λ and T2 phage DNA molecules confined in quartz nanochannels. Such measurements serve a two-fold purpose: (1) we hope to assist in the design of future nanofluidic devices by quantifying the behavior of semiflexible polymers in confined environments and (2) we hope to test existing theories for confined semiflexible polymers.

The ability to produce nanotubes with diameters ranging from a few to hundreds of nanometers and lengths in the tens of micro meters opens new, exciting opportunities for fundamental research on the behavior of liquids under confined conditions as well as the development of novel devices such as minimally intrusive probes and biosensors. We start by summarizing the available experimental data on the transport characteristics of liquids in micro and nano-size conduits with hydrophilic and hydrophobic surfaces. Subsequently, we describe the combined use of controlled nanoassembly and photolithographic techniques for the construction of nanotube-based fluidic devices. Finally, we report on a few measurements of liquid transport through carbon nanotubes.

The transport of water, protons, and nucleic acids through carbon nanotubes was studied with all-atom molecular dynamics simulations. Water is found to fill even narrow pores of sub-nanometer diameter, but the filling is sensitive to the strength of attractive pore-water interactions. Motions of the resulting water wires is fast on a molecular scale. Protons were also found to move rapidly along one-dimensionally ordered water chains with a hopping mechanism. The transport of nucleic acids through nanotube membranes is dominated by polymer conformational dynamics during entry, and hydrophobic attachment to the pore walls during exit.

A new strategy for making low cost, catalytic electrodes is being developed for fuel-cells and electrochemical sensors. The strategy is to synthesize a macrocyclic catalyst derivatized with a functional group (like phosphate or carboxylate), which has affinity for a metal-oxide/metal surface. The purpose of the functional group is to anchor the modified catalyst to the metal surface, thereby promoting the formation of a self-assembled monolayer (SAM) of catalyst on a metal support. Syntheses are given for new ferrocene compounds and metallo porphyrins with anchor groups. The ferrocenes, which are relatively easy to synthesize, were made to learn how to form a stable SAM on a metal-oxide/metal surface. The metallo porphyrins were made for catalyzing oxygen electro-reduction with no platinum. Strategies for attaining an ideal catalytic electrode are discussed.

This paper provides an overview of several on-going research projects on microreactors and microchemical systems in our group. Microchemical systems are a new generation of miniature chemical systems that carry out chemical reactions and separations in precisely fabricated three dimensional microreactor configurations in the size range of a few microns to a few hundred microns. Typical microchemical systems combine fluid handling and reaction capabilities with electronic sensing and actuation, are fabricated using integrated circuit (IC) manufacturing techniques and use silicon and related IC industry materials, polymers, ceramics, glass or quartz as their material of construction. The use of such systems for in-situ and on-demand chemical production is gaining increasing importance as the field of microreaction engineering transitions from a theoretical concept to a technology with significant industrial applications. The paper presents a review of our work on MEMS-based microfabrication, modeling and control of microreformers for hydrogen delivery systems in micro-fuel cells and suggests possible areas of future research.

The high quality of actual epitaxial deposition techniques allows the engineering of electronic, photonic and phononic properties in semiconductor nanostructures for the design of novel multifunctional devices. Here we address the possibility to confine THz acoustic phonons in phonon cavities, and to enhance their coupling with light by embedding them within an optical microcavity. We briefly describe the parameters relevant for acoustic cavity design and phonon engineering in these devices, and we report the observation by high resolution Raman scattering of acoustic phonons confined in planar cavities with one to three confined acoustic modes. Raman efficiency enhancements above 10⁵ are observed for the studied light-sound double resonators. Similarly to optical cavities, the acoustic resonators rely in periodic Bragg mirrors. Extending the parallel between optics and acoustics to other basic devices, we show that non-periodic nanostructures with tailored phononic properties in the THZ range can be designed using optimization algorithms, and characterized by Raman scattering.

A new material platform is described that enables inclusion of nanocrystalline quantum dots into a polymer. This technology is compatible with semiconductor processing and may enable integration of active materials into current waveguide technologies. We describe the steps preformed to fabricate a waveguide chip that contains IR-emitting quantum dots. Optical tests demonstrate guiding and preservation of the quantum dots optical properties through the processing steps. Time resolved optical measurements indicate presence of gain in the InAs quantum dot impregnated polymer.

In this paper, we present the design, fabrication and characterization of the whispering-gallery mode (WGM) miniature sensors for potential use in biosensing at the nanometer scale. In order to understand and investigate the characteristics of WGM resonances, we designed and fabricated a number of sensors with different dimensions. Each sensor is a micro/nano-structure consisted of a microdisk as the resonating cavity and a micro waveguide for light delivery and collection. In addition to the waveguides having uniform cross-section dimensions, tapered waveguide was also considered in our studies. A simulation model was employed to characterize the EM field and radiation energy density of the designed sensors. The gap effects on WGM resonance in terms of quality factor and full width at half maximum (FWHM) were evaluated. Following the design and characterization, the sensors were fabricated in 1.3μm-thick Si₃N₄ film using 248nm optical lithography and conventional silicon IC processing. Top and down SEM measurements of the fabricated sensors were conducted and the data for the sensors in one device are given.

We calculate the imaginary part of the third order optical non-linearity for an array of semiconductor quantum dots in an organic host and show that it leads to large two-photon absorption. The calculated two-photon absorption is greater than currently measured materials. The large non-linearity results from a hybrid exciton formed in the inorganic-organic medium. The band gap of the semiconductor dot determines the spectral region of the resonances that vary from the visible to the near, mid and far infrared regions. We show that relatively small changes in the ratio of the quantum dot size to the quantum dot-to-dot spacing result in significant changes in the non-linearity. We briefly describe applications in communications, optical filters, and bio photonics for thin films comprising these hybrid excitions.

This paper surveys the ongoing evolution of piezoelectric resonator sensors from the micro-technology to the nano-technology regime. Topics covered include fundamental principles of operation, phenomena used for sensing, types of devices and design considerations, material systems, and fabrication. Particular attention is given to the use of piezoelectric resonators in passive wireless RF sensors.

A nanoporous alumina template made from a multilayer metal film structure has been developed that allows for the in situ removal of the electrically insulating alumina barrier layer, exposing a Pt electrode at the pore bases. This barrier free nanoporous system has great potential for DC electrodeposition of a wide variety of materials in the alumina pores. The nanoporous template is fabricated in a more practical way than existing techniques and can be used for the fabrication of nanowires of many materials. Because the template is fabricated directly on the final substrate, no film transfer technique is needed and the substrate can include electrical circuitry. A silicon substrate may be used that provides mechanical stability, facilitates processing, and allows integration with IC components. This will allow for cheap and high efficiency infrared detectors to be fabricated in a practical and cost effective way. The quantum wire devices fabricated in this way can be customized to be used as infrared sensors at a variety of infrared wavelengths.

This paper discusses the use of laterally deformable optical nanoelectromechanical systems (NEMS) grating transducers for sensor applications. For very small changes in the spacing of the nanostructured grating elements, a large change in the optical reflection amplitude is observed, making this an ideal transducer element for detecting very small amounts of relative motion. These devices are also very sensitive to wavelength, and could thus be used as tunable elements for spectrometry, as well as communications or inertial sensing. This anomalous diffraction property was predicted in previous work; here, we experimentally verify operation of these devices and demonstrate a motion detection sensitivity of 10 fm/Hz^1/2, comparable to the most sensitive MEMS transducer. As optical devices, these sensors have additional advantages over electrical sensors, including high immunity to electromagnetic interference and the possibility of integration with fiber optics to create a network of sensors with a single remote optical source and detector.

Capacitive pressure sensors based on surface or bulk MEMS technology have many attributes that make them highly desirable for many applications. The biggest technical challenge of capacitive pressure sensor technology is the creation of a reference cavity. It dictates the packaging approach and therefore the cost of the sensor. In this paper we introduce a new design of capacitive pressure sensor that takes advantage of a novel new wafer level packaging technology - A thin-film sealing technology that allows independent pressure control from high vacuum to high pressure. The new technology seals the vacuum cavity formed by standard surface micro machining technology by a brief melting of a metal layer using a pulsed laser. The ability to form reference vacuum cavity without the need for fusing or bonding with another structure allows the design to be simplified, leading to low cost and high yield.

We report on our design and fabrication of a semiconductor based photonic bandgap nano-membrane device with MEMS features. This device could be used as a basic building block for a reconfigurable optoelectronic integrated circuit that can be reprogrammed for many different functionalities.

The design, construction, and investigation of a reflectometer for measuring return loss magnitude and phase at submillimeter wavelengths is presented. The instrument, which consists of a section of rectangular waveguide and an ensemble of Schottky diode power detectors is designed as a proof-of-principle demonstration and is a relatively simple implementation of the six-port analyzer originally investigated by Engen and coworkers. Design considerations for the reflectometer are presented and measurements in the 270 GHz to 320 GHz range are discussed.

Two heterostructure barrier varactor (HBV) frequency multipliers, a 300 GHz tripler and a 210 GHz quintupler, are designed, fabricated, and tested. The frequency tripler is fabricated with integrated technology, and the quintupler uses flip-chip mounted HBV diodes. The 210 GHz frequency quintupler shows record output power and efficiency. Moreover, the agreement between the simulation and measurement results validates our design methodology. The frequency tripler exhibits a measured output power of 4 mW and efficiency of 5% at 300 GHz. The 210 GHz frequency quintupler also achieves 5% conversion efficiency with 100 mW of input power. With an input E-H tuner, it can provide over 2 mW output power with over 10% bandwidth. Design, modeling and testing of these frequency multipliers are described and presented in this paper. Some possible methods to improve these frequency multipliers are addressed.

THz frequency sources have a variety of applications ranging from molecular spectroscopy, atmospheric remote sensing, scaled radar range systems, sensing and monitoring of chemical and biological molecules to wireless communications. However, there is a lack of frequency tunable sources at these wavelengths. A frequency upconverter can be used to generate frequency tunable sidebands as a tunable high frequency source from a fixed source, such as Far Infrared (FIR) Laser. The development of 1.6 THz frequency upconverters with integrated diode circuit are described in this paper. The integration of the diode with the embedding circuit enhances mechanical robustness and makes the circuits easy to handle compared with a whisker-contacted diode structure. A nonlinear analysis is used to determine the optimum varactor diode parameters. Through the optimization, the circuit quartz substrate thickness is chosen to be 10 um and the anode diameter is determined to be 1 um. With the non-ohmic cathode contact technique and air bridge process (eliminating the surface channel etch process), the 1.6 THz integrated circuits were fabricated in University of Virginia with high yield. Furthermore, the conversion loss is measured and presented. The test setup consists of an FIR Laser, beam splitter, polarizer, parabolic mirror, silicon etalon and other optical components. The average conversion loss was measured to be approximatly 25 dB over 8 GHz microwave pump. Equivalent circuit models and simulations are presented to corroborate these results.

Two methods to build submicronic self-aligned devices based on SOI MOS technology have been studied. The foreseen application of these techniques is the fabrication of self-aligned double gate SOI MOS transistors. Both of these methods make use of the implantation of a buried mask underneath the active silicon layer and aligned with the top gate. The mask is revealed by a selective etching between doped and undoped polysilicon. In one case Tetra-methyl Ammonium hydroxide solution (TMAH) is used to create a negative mask, etching the undoped zones. In the second case, a positive mask is revealed in a solution made of Hydrofluoric acid, Nitric acid and Acetic acid (HNA), etching the doped zones. Once the mask is revealed, the process differs from a normal CMOS process by the addition of two Chemical Mechanical Polishing (CMP) and bonding steps. The realized demonstrator proves the feasibility of both the positive and negative buried mask.

This work reports on theoretical studies of optical properties of gold nanospheres and nanorods with various aspect ratios, embedded in a porous anodic alumina matrix. When the alumina template is made under certain conditions, nanostructures with diameters in the 15-25 nm range can be synthesized. These nanoparticles have potential applications in optical filters and sensors.

Multiphoton processes are playing a significant role in microfabrication, patterning of nanostructures, formation of photonic band gap materials and ordered micro/nanoarrays. However, many of the chromophores with large two-photon absorption used for these applications are actually hybrid materials in which the two-photon absorption is coupled to an excited state absorption. This coupling makes the detailed analysis of the photophysics significantly more complex. We have developed a numerical technique to investigate hybrid multiphoton processes. Our numerical method compares very well with published results.

Self-assembling is a widely accepted for manufacturing of nanostructured materials and nanometer-scale devices. In this paper, coating of titanium oxide nanoparticles into a porous alumina template by electrophoresis technique was investigated. Aluminum template was made by anodization of aluminum plate in an oxalic acid solution. The diameter of porous aluminum was in the range of 35-45 nm. The electrophoresis deposition of nanoparticles of titanium oxide was carried put using a colloidal titanium oxide complex. The structural and composition of these films were investigated using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. It was found that the titanium particles were loaded into the porous cavity of nanotemplate under bias conditions. Self-assembled titanium dioxide nanoparticles can be used in different applications including catalysts, sensors, photonics and biomedical devices. In this paper, results of our preliminary experiments are reported.

The thermal plasma method for producing of nanoparticles provides higher throughput compared to the other methods. The synthesis of nanoparticles in a thermal plasma reactor is a two-step process, including precursor dissociation and the nucleation and growth of the produced particles. In the present paper we describe the design of a production line based on the thermal plasma method for producing of nanoparticles. The use of a DC-RF-RF hybrid plasma torch, a non-destructive and non-invasive diagnostics, and in-situ control ensure the production of high-quality products.

Spherical aberration is important in focused ion beam applications where large aperture angles are needed to obtain high beam currents because it results in large tails on the current density distribution. Merwe has shown that for coaxial lenses, negative spherical aberration can be found for rays pass through zonal regions. Merwe’s calculation is valid only for periodic or quasi-periodic lenses and requires a constant axial potential distribution. We have calculated zonal focusing properties of lenses with axial electrodes using nine-point finite difference method and direct ray tracing. Our calculation results indicate that an axial electrode protruding partially into the lens can correct the spherical aberration. When a three-element electrostatic lens is operated at deceleration mode, the introduction of an axial electrode creates zonal regions where the spherical aberration is negative. At deceleration mode, the induced surface charges on the axial electrode have an opposite sign relative to the primary beam. This is in agreement with our previous findings on the study of the correction of spherical aberration utilizing space charges. Same phenomenon was found when an axial electrode is used in conjunction with a cathode lens.

This paper describes the use of a unique combination of an environmentally stable chemically amplified photoresist (UV113, Shipley) and a copolymer of methyl styrene and chloromethyl acrylate P(MS/CMA) resist (ZEP520, Zeon), without any additional intermediate layers, in the fabrication of micro- and nanochannels. The two resists used are innocuous to each other during the designed process flow, providing flexibility, high resolution, greater throughput and ease of use. We have also determined that the maximum channel length is limited by diffusion and mass transport effects, and that sub-100 nm nanochannels can be obtained with 30 micron lengths.

The manufacturing of nanoscale devices with sizes smaller than 100 nm is founded on the quantum physical phenomena. We proposed the new nanoscale device with photoacoustic switching. The memory cell can be made by means of two thin silicon surface layers one of which contains oxygen in Si-O-Si bonding. The charge storage is caused by inserting on clean silicon layer the oxygen incorporated with silicon. The mechanical deformation of upper oxidized silicon layer results in shift of atomic positions. The oxygen appearance on the silicon surface is reflected on electronic structure as new defect level inside band gap. The electrons are stored on this oxygen related level with energy position Ec-0.18 eV. By applied bias voltage we realize the erase procedure by removing the stored electron. The silicon surface should be prepared because the oxygen incorporation depends on the chemical properties. The electronic structure of oxidized silicon surfaces with (111) and (100) orientation was tested by using second harmonic generation response. The characteristic time of storage, 1 ns, was measured by using the laser time-resolved short pulse spectroscopy. We used modelocked mode of laser system with pulse duration 120 ps. The speed of switching was approximately 10¹³ Hz.

Future generations of flexible, transparent electronics will require the use of polymer based thin-film transistors (TFTs) exhibiting high carrier mobility. The problem of enhancing TFT characteristics is addressed in this report. We investigate the nanoscale, self-assembled monolayer (SAM) influence on organic-based thin film transistors (OTFT) at the interface between semiconducting polymer and both the source/drain metal contacts and the insulator. Capacitance-voltage (C-V) characteristics help to elucidate the role of SAMs in the OTFT structure and the charge injection mechanism. Positive trends and parasitic effects are also addressed in characterization.

As the rate of gene discovery accelerates, more efficient methods are needed to analyze genes in human tissues. Genechip, a kind of new device, is composed of DNA probes immobilized on a solid substrate. With the advantage of the high throughput information, genechip has become one of the best solutions to detect and analyse the mutations in genes. Hypertrophic cardiomyopathy (HCM), the most common cause of the sudden death in the young, is one of the diseases damaging people health most badly. It is an autosomal dominant disease. More than 55% of the HCM patients are genetic. The mutations of exon 8 in the Cardiac troponin I (cTnI) gene are closely associated with Family Hypertrophic Cardiomyopathy (FHCM). Our purpose is to perform the assay of the mutations in exon 8 in cTnI gene based on the genechip theory and technology. Special probes were designed to fabricate the genechip to detect the mutations in cTnI gene simultaneously. We designed two oligonucleotide sequences 5’-end labeled with fluorescein, one simulating wild-type and the other simulating mutant. We mixed oligonucleotide I and II together to simulate heterozygote. After optimizing the hybridization protocols, the fabricated genechip can detect the mutations in exon 8 in cTnI gene with relative high sensitivity and specificity. When applying the fabricated genechip to detect the target DNA sequence, we found that the fully complementary probe gave a fluorescent signal almost 50% stronger than that of the one base mismatched one, which is in accordance with the result from theoretic estimate. It is believed that an applicable special genechip can be developed for investigating and diagnosing FHCM after further improvement.