Results of experimental and numerical researches of model radiation sources based on low inductive capillary tubes with the close placed return coaxial current-carrying conductors and long transporting lines are presented. It shows large opportunities of similar systems in obtaining noncoherent radiations from hard x-ray up to visible light and coherent radiation of EUV range of spectrum.
The development of an electron resist on PMMA basis was experimentally shown to depend not only on an exposure dose but on current density and exposure sequence as well. Various exposure doses are required to obtain a uniform development rate at different beam currents, with an exposure dose being the lager, the higher the current rate. Maximum dose changes can be as large as several tens of percent. A model is proposed which is a development of the temperature effect model, i. e. the dependence of an absorbed dose on resist temperature. The model supposes that a resist molecule is in an intermediate state after the interaction with an electron, from which state it can either spontaneously break down, or spontaneously return to the unexcited state, or else return to the unexcited state due to the effect of electrons. A model experiment was made which helped determine the model parameters, the time of intermediate state relaxation, and the characteristic current density. Using the values of the model parameters, it was found that the rate of resist development in some areas exposed to equal doses can be different, with the difference being approximately as large as two times.
Proc. SPIE 6260, Ultra shallow <i>p</i>+-<i>n</i> junctions in Si produced by plasma immersion ion implantation, 626003 (10 June 2006); doi: 10.1117/12.676912
We present the results of experiments on PIII application to form the ultra shallow highly doped junctions for ULSI CMOS technology. Experiments were carried out with plasma immersion implanter designed for 150 mm wafers. Two-step process includes the Si-surface pre-amorphizing implantation by Ar+ (Xe+) ions from plasma and subsequent boron doping of n-Si wafer from low pressure plasma of BF3 (ICP HDP-source) by flux of accelerated molecular ions without mass separation. Accelerating voltage of bias pulses is varied in the range of 0.7 - 4.5 kV. Implanted boron was activate by both RTA and it combination with furnace annealing technique. Under experimental conditions, the p-n junctions with depth of 40-70 nm were formed with sheet resistance of p+ layers in the range of 100 - 300 Ohm/square.
Investigation of low-temperature annealing of Si samples implanted by As+ and Sb+ ions under influence of intensive low-energy hydrogen atom flow (j = 1015 cm-2 s-1) was carried out. It was shown, that samples, annealed in atomic hydrogen, have increased mobility and concentration of charge carriers, in comparison with samples annealed in vacuum. The phenomenon was observed in the temperature interval 300-500°C and it was investigated by Hall effect method and Reserford Backscattering Spectroscopy (RBS) of He+ ions. Positive influence of atomic hydrogen on electrical parameters of implanted layers was already revealed in the case of short process duration (5 minutes) and it was most brightly revealed at T = 300-400°C. At the same time, the influence of atomic hydrogen on annealing of self-interstitial defects in Si samples, implanted by Sb+ ions with doze 3×1014 cm-2, was insignificant. Moreover, in the case of low implantation doze (3×1013 cm-2) atomic hydrogen reduces defect annealing. Factors that may be responsible for existence of hydrogen-stimulated annealing phenomenon of implanted layers are discussed.
Proc. SPIE 6260, Formation of conductive structures in insulate layers by selective removal of atoms technique, 626005 (10 June 2006); doi: 10.1117/12.677147
The structure and electric properties of initial oxides and metals (Bi, Ag, Cu, Ni, Co, Mo and W) produced by Selective Removal of oxygen Atoms technique (SRA) were studied. It was found a correspondence of electrical conductivity of SRA metals and pure sputtered metals films. At the same time, low resistance of some oxides, for instance CuO, will initiate big leakage currents inside the layer. Among the investigated materials special attention will be paid to SRA Bi, Mo and W because of the high values of contact resistance and puncture potential with initial oxides. It is shown the adaptability of Selective Removal of Atoms technique for formation of conductive insulated structures in layers for new micro and nano-electronic devices.
Proc. SPIE 6260, Dense arrays of Ge nanoclusters induced by low-energy ion-beam assisted deposition on Si02 films, 626006 (10 June 2006); doi: 10.1117/12.676916
Ge islands less then 10 nm in base diameter and with a number density of about 8×1011 cm2 were created on Si02 films by low-energy ion-beam assisted deposition in high vacuum. The structures obtained were analyzed by Electron Spectroscopy for Chemical Analysis, Atomic Force Microscopy and High Resolution Electron Microscopy. It was found that due to desorption at 300-375 °C less than 50% of Ge deposited remains at the surface. Only pulse regime of ion-beam action results in formation of nanoclusters. It is suggested that the simultaneous nucleation of Ge islands at pulse ion-beam action is the main reason of high homogeneity of size distribution of Ge nanoislands.
New technology of obtaining of SOT-structures by ionic synthesis of buried silica glass layers has been proposed. This technology is based on physical processes of formation of a new phase that appears in ion-synthesized Si-B-O and Si-P-0 systems at heat treatment. It has been shown that synthesized layers can be formed at significantly moderated annealing conditions than in the case of SIMOX-process. The structures have been studied by secondary ion-mass spectrometry (SIMS), Auger-electron spectroscopy and X-ray photoelectron spectroscopy (XPS). The study of electrical characteristics of the structures with buried silica glass layers includes the current-voltage and capacity-voltage measurements.
Proc. SPIE 6260, Radiation-induced structure modification in monocrystalline silicon under high-energy C6+ irradiation, 626008 (10 June 2006); doi: 10.1117/12.677148
This paper concerns surface morphology and structural modification in silicon after 1.2 GeV C6+ irradiation. A number of experimental techniques was used, including atomic force microscopy, x-ray photoelectron spectroscopy and x-ray diffraction studies. The formation of nanometer-sized hillocks on the surface was revealed. In the bulk of parallel-irradiated specimens amorphous regions formation was discovered.
Proc. SPIE 6260, A self-consistent model for the HCl dc glow discharge: plasma parameters and active particles kinetics, 626009 (10 June 2006); doi: 10.1117/12.677019
In this work, the investigations of plasma parameters and active particles kinetics in an HCl dc glow discharge were carried out using the combination of plasma diagnostics and plasma modeling. The modeling was based on the self-consistent solution of Boltzmann kinetic equation and the balance equation of chemical kinetic for neutral and charged particles. It was shown that the electron impact dissociation of HCl is the main source of both Cl and H atoms while the total balances for all kinds of neutral particles are noticeably influenced by the volume atom-molecular reactions. The population of the vibrational energy levels for HCl molecules was found to be low, but the role of the HClv>0 in the negative ions formation process cannot be neglected. The assumption of the first-order heterogeneous recombination kinetics for both Cl and H species provides a good agreement between the modeling and plasma diagnostics data.
In present paper the description of dynamic Langmuir probe technique is given and the results on plasma parameters obtained in ICP-discharge in pure CHF3 gas are discussed. It was proven that using of DLP-technique is the way to obtain relevant probe data in polymerizing plasmas. Side effects of the thermionic emission from probe tip were revealed. Although emissive probes can be used to simple measure of plasma space potential, the emission can cause sufficient distortion of I-V curve, measured values of electron temperature, and EEDF curve. The effect of emission was experimentally measured and corresponding work function of electrons from probe surface was estimated.
A theoretical study is presented of transmission spectra formation of perfect two dimensional (2D) photonic crystals (PCs) composed of dielectric cylinders arranged parallel to the electromagnetic wave's electric vector in the square lattice. Layer-by-layer transmission spectra are computed on the basis of a Riccati equation for the matrix wave reflection coefficient from a 2D PC slab and Poynting theorem, regarding 2D PCs as a stack of conservative gratings (layers of non-absorptive rods). The lowest (main) and high-order Mie resonances in a single cylinder and the Bragg-like multiple scattering of electromagnetic waves are determined as three mechanisms of formation and frequency position of two opaque bands, with narrow peaks in one of the bands in the transmission spectra of 2D PCs. It is argued that higher-order Mie resonances are responsible for the transmission peaks within the additional band of a perfect crystal. The possibility of opaque band engineering is discussed. In particular, it is demonstrated that filling fraction of volume occupied by cylinders as small as under half a percent does not destroy the opaque band of 2D PCs.
Proc. SPIE 6260, Boron distribution profiling in asymmetrical n+-p silicon photodiodes and new creation concept of selectively sensitive photoelements for megapixel color photoreceivers, 62600C (10 June 2006); doi: 10.1117/12.677027
Experimental results on spectral photo responsivity obtained for silicon n+-p photodiodes with implanted p+ layer in a silicon substrate are represented. It is demonstrated, that such p+ doping effectively shifts long-wave edge of the photodiode's spectral sensitivity in optical range of light spectrum, depending on the p+ layer bedding depth. A new concept of selectively sensitive photoelements development was stated for megapixel color photoreceivers on the basis of n+-p photodiode structures, containing one or more different (in depths) implanted layers, which form color separation potential barriers and lateral diffusion channels required for collecting of minority carriers generated by quanta of different wavelength.
Silicon nanopowders were produced using power electron-beam-induced evaporation of bulk silicon ingots in various gas atmospheres. Optical properties of the nanopowders were studied with the use of photoluminescence and Raman spectroscopy techniques. Photoluminescence peaks in the visible region of the spectrum have been detected at room temperature in silicon nanopowders, produced in argon gas atmosphere. Strong short-wavelength shift of the photoluminescence peaks can be result of quantum confinement effect for electrons and holes in small silicon nanocrystals (down to 2 nm in diameter). The size of silicon nanocrystals was estimated from Raman spectroscopy data. The calculated in frame of effective mass model optical gaps for silicon nanocrystals of spherical shape are in good correlation with experimental photoluminescence data. With the use of silicon ingot evaporation by power electron-beam at air atmosphere the Si02 nanopowders were produced. The attempts of deposition of silicon nanocrystal films from the nanopowders on silicon substrates were carried out.
Proc. SPIE 6260, Synthesis of AIIBV semiconductor nanocrystals by electrochemical deposition and SILAR techniques, 62600E (10 June 2006); doi: 10.1117/12.677059
We considered the basic principles of AIIBVI (CdS) semiconductor deposition from aqueous solution by ECD and SILAR methods. Obtained results confirm that quality of CdS film synthesized by electrodeposition is practically identical to single crystal quality. The SILAR deposition allowed us to investigate quantum confinement in CdS nanocrystals.
One of the important problem of transition from micro- to nanomeasure elements in modem electronics is the creation of dielectric layers with high permittivity and less than 200 nm thickness. The opportunities of using titanium, hafhium, aluminium, silicon nitride, barium titanium, lead and strontium oxide are considered. One of the most promising directions is the usage of solid solutions of Ti-Zr films.
In this work results of investigation of technological processes of gate structure formation for devices with less then 100 nm channel length were presented. Gate structures with high-k (YSZ) gate dielectric and silicide (CoSi2) electrodes were analyzed. Influence of silicide process parameters on homogeneity of silicide formed in narrow trenches were considered.
It is shown that copper thin film conductors (10-100 nm thickness) have not the defined temperature of melting. The melting of 20 nm copper thin film starts at 610 °C after 5 mm and, at the same time, at 470 °C after 3 h 40 mm. The melting of 100 nm copper thin film starts at 740 °C after 7 mm and at 640 °C after 2 h 25 mm. The kinetics of this phenomenon has been studied. The stages of process have been shown. The activation energies of thin film melting have been estimated. It is demonstrated that the activation energy of process is decreased with the copper film thickness reduction. The character of activation energy changes has been explained with point of view of the hydrodynamics.
Sb-doped SnO2/SiO2 nano-composite thin films prepared by sol-gel dip-coating method have been studied. By using X-ray diffraction (XRD), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy, detailed investigation on the structure and morphology of the films has shown the crystalline grain size of Sb-doped SnO2/SiO2 thin films is about 34nm, with larger specific surface area and duty porosity, which is fit for gas-sensing materials. The adulteration of SiO2 particles leads to the condensation of Sn-OH and the strengthening of gel network, and improve the adhesion of the films. In addition, the optical properties of the thin films were studied by UV-Vis spectra and p-polarized light reflectance angular spectrum. The results showthat the optical transmissivity of Sb-doped SnO2/SiO2 thin films is higher, near 95% in visible spectrum range, the measured optical gap is found equal to 3.67eV, also the films take on smaller refractive index and extinction coefficient compared with those of the SnO2 and Sb:SnO2 films, which is compatible with the semiconductor substrate in the solar cell. Further, the gas-sensing test was made to three kinds of gas C3H8, C2H5OH and NH3 in our novel high sensitive scheme for optical film sensors. The results indicate that Sb doping to SnO2 films greatly improves the gas sensitivity to C2H5OH, and the gas sensitivity of Sb:SnO2/SiO2 nano-composite thin films are higher than that of Sb:SnO2 thin films. The detection sensitivity of this optical film sensor is available to 10-1ppm provided that the resolution of reflectance ratio is 10-2.
Proc. SPIE 6260, Controlled change of structure and properties of nanometer polymer layers deposited by electron beam polymerization from vapour phase, 62600J (10 June 2006); doi: 10.1117/12.677152
Electron beam polymerization of monomers from vapour phase is advanced method of thin polymer layers (TPL) deposition on solid substrates. The structure features and properties of TPL formed from tetrafluoroethylene and methylmethacrylate vapour at different E-beam current densities were found to be different strongly. In 1-10 μA/cm2 field the low molecular mass PTFE films with tape and disk supramolecular structures formed. These films are low thermostable (to 250-300°C) because of sublimation under heating. Macromolecules in these films are regulated (mesomorphic state). The polymer chain axes are oriented perpendicularly toward substrate surface. In 102-103 μA/cm2 field the films with high thermostability (400-450°C) form. These films are probably crosslinked. In 104-106 μA/cm2 field the amorphous, strongly crosslinked, high thermostable, high uniform films form. Polymethylmethacrylate (PMIMA) films formed at 1-10 μA/cm2 rapidly dissolve in organic solvents. The PMMA films deposited at 102-103 μA/cm2 only swell in organic solvents. The observed differences of structure and properties of films deposited by E-VDP method are caused probably by different balance of chain polymerization and polyrecombination mechanisms in the film deposition processes. In highest current density range the polyrecombination mechanism predominates. In low current density the main mechanism of deposition is the radical-chain polymerization. The results obtained show great possibilities of controlled change of properties of E-VDP films deposited from the same precursor.
Here we investigate theoretically the phonon-assisted spin relaxation of holes in Ge/Si quantum dots (QD). This mechanism is dominant for an isolated QD in external magnetic field H≥O.1 T. In the temperature range T<60 K there are two competitive phonon-assisted spin flip processes: direct one-phonon process (first-order to perturbative strain field) and Raman-type process (second-order). In the framework of tight-binding approximation, relaxation times τ(1) and τ(2), corresponding to these processes, were obtained. The relaxation time τ(1) weakly depends on temperature: τ(1)→const for T→0 (spontaneous transitions) and τ(1)~T-1 for higher T (when induced transitions are dominant). Magnetic field dependence of τ(1) is rather strong: τ(1)~H-5, while the rate of Raman-type processes is almost field-independent when T>gβH/k and strongly depends on the temperature: τ(2)~T-7.
The presented work is devoted to investigation of electrical properties of metal-oxide-semiconductor structures containing nanocrystals in silicon dioxide. Nanocrystals were fabricated in the middle of SiO2 layer with use of ion implantation and following thermal treatments at a temperature of ~1000°C. Capacity-voltage (C-V) and current-voltage (I-V) characteristics were measured at room and nitrogen temperatures at various frequencies from 1kHz up to 145kHz. I-V characteristics of MOS-structures with 75nm thick SiO2 layer demonstrated repeatable steps. Position of steps qualitatively corresponds to theoretical one, which were calculated using electron state energies for nanocrystals with size 5 nm. Steps due to Coulomb blockade effect on spin degenerated levels in nanocrystals are resolved in experiment. CV- characteristics displayed sharp frequency dependent peak possibly corresponded to approximately mono-energetic states, which provides transport of electrons through SiOx.
Proc. SPIE 6260, Peculiarities of the electrical characteristics of the pseudomorphous SiGe/Si MODFET structures with a corrugated surface, 62600M (10 June 2006); doi: 10.1117/12.677196
In the present activity the properties of the Si/SiGe MODFET structure with a Si electronic transport channel in SiGe layer is studied. Larger attention is given to the interfaces channel and their influence on the electrical characteristics of a structure. Is shown, that in actual structures the kinetics of molecules disintegration not only determine a structure profile near interfaces, but also can promote the origin of nanostructural compositions in these areas. It can exhibit in a formation of arrays of quantum dots from one of component of solid solution on the layer boundary, resulting to a lot of effects as in longitudinal and transversal conductivity of the epitaxial structure.
Proc. SPIE 6260, Controlled interference effects of spatial reproduction and multiplication for electron waves in semiconductor 2D nanostructures, 62600N (10 June 2006); doi: 10.1117/12.677202
Effects of spatial nonhomogeneity for the probability current density jx (x,z) (or a quantum-mechanical current density ejx (x,z), e is the electron charge) in the semiconductor 2D nanostructures in the form of joints in the direction of propagation of the electron wave (the x-axis) of narrow and wide (on the z-axis) rectangular quantum wells (QWs) (z-axis is the axis of the quantization) and the possibility to control these effects have been theoretically studied. In the first part of our article we show that the nonhomogeneous distribution of the jx (x,z) arises because ofthe interference of electron waves spreading in the wide QW simultaneously in different electron subbands. Special attention is given to effects of spatial reproduction and multiplication for electron waves in such nanostructures. It is shown that transverse distribution jx (0,z) existing at the entry of the wide QW is reproduced with some accuracy at a definite distance X1 from the joint and splits in symmetric (along the z-axis) 2D nanostructures into p identical profiles of the intensity lower by p times at the distance X1/p. This picture is reproduced periodically in cross-sections Xq = qX1 (q and p are integers). The results of numerical calculations of these effects in symmetric nanostructures are given. The possibility to control these effects by the transverse (along z -axis) constant electric field strength F being created by gates in the wide QW in symmetric 2D nanostructures with rectangular QWs was studied theoretically.
The influence of surface roughness scattering on channel conductivity of ultrathin body MOSFET in a quantum mechanical approach is considered. Analyzing a counterplay between Coulomb and surface scattering we show that a transition from dominating Coulomb scattering towards dominating surface scattering occurs when the film thickness is reduced to few nanometers. Evidently, the "critical" film thickness depends upon roughness characteristics and surface charged defects density. We have also examined the ripple-wise roughness which gives rise 4th power law of dependence of mobility on film thickness. In spite of a smaller power compared to that for smooth roughness the ripple-wise roughness could dominate just on Si/Si02 interface due to high discrepancy in lattice constants of contacting materials.
Proc. SPIE 6260, Structural and electrophysical properties of pseudomorphic GaAs/InGaAs/GaAs quantum wells: effect of thin central AlAs barrier, 62600P (10 June 2006); doi: 10.1117/12.681733
Electron transport, optical and structure properties of the shallow pseudomorphic quantum wells (QW) GaAs/InGaAs/GaAs are studied by electrophysical, photoluminescence and X-ray double-axes diffractometry methods. It is revealed that insertion of a thin AlAs potential barrier in the center of QW leads to efficient changes of subband structure and mobility. In the case of shallow and narrow quantum wells the observed decrease of mobility is due to appearance of the different scattering mechanism. X-ray diffractometry study is undertaken in order to distinguish whether it is interface roughness scattering from the introduced barrier or another scattering mechanism.
Proc. SPIE 6260, The influence of relaxation on the structure and boundary shape of adatom islands on an incommensurable substrate, 62600Q (10 June 2006); doi: 10.1117/12.681755
The structure of monolayer (adatom island) is investigated with taking into account of relaxation of atoms in a changeless field of substrate, which is incommensurate to the monolayer structure. The influence of relaxation of the structure and shape of adatom island on its orientation in relation to the structure of substrate is shown. It is established that the monolayer structure has a superstructure with periodicity which is inversely proportional to the incommensurability. It is shown that the shape of an island and its orientation in relation to the structure of substrate changes during its growth. The results of calculations are compared to the experiment.
The research of influence of the thermodiffusion parameters -temperature gradient ∇T and heat of transport Q* on concentration profiles is carried out for diffusion from an instantaneous plane source and an extended source of infinite extent. The estimations of heats of transport of the P and B in silicon are made at nonisothermal annealing. The obtained results correspond to theoretical estimations and give meanings ofheat oftransport ~103 eV.
The current status of the material and interfaces aspects of the problem of SFS Josephson junction fabrication is reviewed and recommendations for selection of ferromagnetic materials are formulated. It is shown that additional pair braking mechanisms at SF interfaces, as well as spin flip and spin orbit scattering in the F films should be taking into account for the data interpretation. The results of theoretical studies of the influence of spin-flip and spin-orbit scattering on the oscillations of critical current with the thickness of the ferromagnetic layers are summarized and discussed. The form of the relation between supercurrent J and order parameters phase difference φ across a junction is analyzed. It is shown that the Josephson current across the structure has the sum of sinφ and sin2φ components and that two different physical mechanisms are responsible for the sign of sin2φ.
Proc. SPIE 6260, Calibration of quantum detector of noise based on a system of asymmetric superconducting loops, 62600T (10 June 2006); doi: 10.1117/12.681803
The quantum oscillations V(Φ/Φ0) of the dc voltage are induced on segments of asymmetric superconducting loops by an external ac current or noise. The dependencies of the amplitude of V(Φ/Φ0) on amplitude of inducing ac current are measured at different temperatures below superconducting transition Tc on aluminum asymmetric loops and systems of the loops connected in series. The measured values of the maximum amplitude of the quantum oscillations V(Φ/Φ0), the amplitude of the ac current inducing this maximum dc voltage and the critical amplitude of the ac current decrease with temperature increase to Tc. The extrapolation of these measured dependencies to the region near superconducting transition allows to make a calibration of asymmetric superconducting loops as quantum detector of noise. The calibration restores an amplitude profile of the noise pulses from a measured temperature dependence of an amplitude of the quantum oscillations V(Φ/Φ0) induced by this noise. It is found that rectification efficiency, determined as relation of the maximum amplitude of the quantum oscillations V(Φ/Φ0) to the ac current amplitude inducing it, decreases near superconducting transition Tc. High efficiency of rectification observed below Tc is consequence of irreversibility of the current-voltage curves. Increase of the rectification efficiency is achieved in multiple series connected loop structures.
Switching of magnetic junctions by spin-polarized current is considered with spin-transfer and spin-injection torques taking into account. In contrast with previous works, the mobile electron spins are assumed to be non-pinned both in collector and emitter layers. As a result, both parallel and antiparallel configurations can become unstable, depending on the layer parameters.
The vast majority of experimental Moessbauer spectra of nanomagnets are treated within a static hyperfine structure for which the line positions and intensities can be described in terms of static magnetic fields acting on nuclei. As has been recently found, the rotation of magnetic moments of nanoparticles results in a renormalisation of the nuclear g-factors, accompanied by a qualitative transformation of absorption spectra. In particular, along with magnetic sextet well known in the Moessbauer spectroscopy of 57Fe isotope, partial spectra consisting of 'magnetic' quintuplet, quartet, triplet and even doublet of lines can be formed. Such a transformation of Moessbauer spectra depends not only on the magnitude of the rotation frequency but also on its sign, which, in turn, may be dictated by the shape and constants of magnetic anisotropy. The predicted effects can essentially modify the conventional scheme of analysis of experimental Moessbauer spectra of nanomagnets.
Magnetic molecular nanoclusters are promising components for the design of new magnetic materials and ultrahigh density recording media. The study of these materials is also important due to the possibility of their use in quantum computers, magnetocaloric and magnetooptic devices. The key feature of these materials determining the possibility of their practical use is the value and character of exchange interactions between magnetic ions. But the study of exchange interaction in clusters with more than two paramagnetic centers is nowadays the subject of an intense research and this problem is far from the complete solution. In this paper on the base of Hubbard model we present microscopic model for the calculation of the exchange interactions in a ferrimagnetic ring taking into account hopping term (t) and on site Coulomb repulsion (U). The Heisenberg exchange interaction term and three-spin exchange interaction terms are obtained. The Heisenberg exchange interaction term has the leading order t2/U and three-spin exchange interaction term has the leading order t4/U3. It is shown that the physical reason for the appearance of a three-spin exchange interaction is a ring hopping between four sites. This model is applied to the interpretation of the experimental data obtained by remagnetization of the ferrimagnetic ring Mn6R6. Remagnetization process in Mn6R6 is described on the base of spin Hamiltonian taking into account Heisenberg and three-spin exchange interactions. Exact calculation of the energy and spin structure of this spin Hamiltonian is made. The performed calculations show that in the framework of the Heisenberg model it is impossible to obtain acceptable agreement between theoretical calculations and experimental data. It is shown that acceptable agreement between experimental data and results of theoretical calculations can be obtained only by taking into account three-spin interaction. In this case the value of the three-spin interaction is rather large and the ratio of three-spin exchange constant and Heisenberg exchange constant may be as much as 0.14. According to our microscopic model this value corresponds to the ratio t/U=0.19. The dependence of the values of critical fields on the ring size is also investigated. It is shown that upper and lower critical fields has rather weak dependence on the ring size. This allows an increase of the accuracy of determination of exchange interactions by investigating the remagnetization process of rings with different size. The key feature for quantum computing is the transition from quantum to classical behaviour as ring size is increased. The calculations made show the strong influence of three-spin interaction on this transition. Due to the three-spin interaction this transition became nonmonotonic. Also apparent shift of transition to the classical behaviour to the larger values of the ring size is observed. This increases the working range for quantum computing.
Formation of ordered arrays of Ag nanowires and nanodots on stepped Si(557) silicon surface have been studied by scanning tunneling microscopy, low energy electron diffraction and Auger electron spectroscopy. It was found that the shape of the Ag islands being formed depends drastically on preliminary exposure of a Si sample in the vacuum chamber. This effect may be caused by the adsorption of small amounts (less than a percent of a monolayer) of oxygen on Si
surface from the residual atmosphere in the vacuum chamber. When silver is deposited on a clean Si(557) surface the wide epitaxial silver islands form. After exposure, silver nanostructures can be obtained in the form of nanowires extended along the edges of steps or nanodots ordered in lines parallel to these edges depending on the exposition.
Nanowires of various metals were embedded into porous anodic alumina (PAA) by ac electrochemical deposition while the PAA layers remained on the Al substrate. Semiconductor nanowires of MeSx and MeSey were formed by sulfurization and selenization of the metal precursors. Deposited metal and semiconductor wires were characterized by scanning electron microscopy, scanning probe microscopy, Auger-spectrometry, and x-ray diffraction. Optical properties of silver nanowires, embedded into PAA matrix were investigated by spectrophotometry. Photovoltage spectroscopy was applied to demonstrate semiconductor properties of CdS nanowires prepared by the proposed technique.
The technology of fabrication of the self-organizing ranked mask on base porous aluminum for etching nanosize pores in silicon has been considered. The experiments on obtaining the nanosize matrix structures in silicon have been conducted.
Germanium nanocrystals in GeO2 films have been obtained with the use of two methods and have been studied. The first method of Ge nanocrystal formation is a film deposition from supersaturated GeO vapor with subsequent dissociation of metastable GeO on heterophase system Ge:GeO2. The second method is growth of anomalous thick native germanium oxide layers with chemical composition GeOx(H2O) during catalytically enhanced Ge oxidation, x is close to 1. The obtained films were studied with the use of photoluminescence, Raman scattering spectroscopy, high-resolution electron microscopy. Strong photoluminescence signals were detected in GeO2 films with Ge nanocrystals at room temperature. "Blue-shift" of the photoluminescence maximum was observed with reducing of Ge nanocrystal size in anomalous thick native germanium oxide films. So, the correlation between reducing of the Ge nanocrystal sizes (estimated from position of Raman peaks) and photoluminescence "blue-shift" was observed. The Ge nanocrystals presence was confirmed by high-resolution electron microscopy data. The optical gap in Ge nanocrystals was calculated with taking into account quantum size effects and compared with the position of the experimental photoluminescence peaks. It can be concluded that a Ge nanocrystal in GeO2 matrix is a quantum dot of type I. It was shown, that "band gap engineering" approaches can lead to creation of Ge:GeO2 heterostructures with required properties. This heterostructures can be perspective for using in opto-electronics, for creation of elements of quasi-nonvolatile MOS memory using Ge nanocrystals as traps for electrons or holes, etc.
The influence of the thermal regimes on the formation of ordered porous anodic alumina was investigated. The process of the formation of the high ordered films of porous anodic alumina was developed.
Proc. SPIE 6260, Combined electromagnetic mirror as the probable breakthrough tool in an ion nanotechnology, 626012 (10 June 2006); doi: 10.1117/12.683392
It is offered the using of new, simpler and more stable electron - optical element - the combined electromagnetic mirror as the corrector of the axial chromatic aberration in ion optical systems. Such element, together with the system of separation of beams, forms the corrector. The use of such corrector allows powerfully lowering the coefficient of chromatic aberration of ion objectives. The maximum of the relative magnitude of the coefficient lowering is equal to the inverse coefficient of stability of electrodes voltage in ion microscopes and currents stability in the magnetic lenses of electron microscopes (i.e. in 105 times). In FIB-systems it will allow to create sondes of sub-nanometer size and also it will allow to solve the problem of creation of single ions implanter for technology of a solid-state quantum computer. It's shown that resolution (or FWHM) of 2 nanometer may be achieved by reactive ion etching with the using of focused ion beam on the base of combined electromagnetic mirror as compensator of chromatic aberration of ion objective lenses. It will allow to create the templates for imprint and masks for proximity lithography with the size of half pith of 2 nm.
Problems of nanoobject linear size measurements on scanning electron microscopes (SEM) have been discussed. It is suggested to use the relief pitch structures of the MShPS-2.0K measure as the line width standard. The geometrical model of signal formation by these structures on high and low voltage SEM's has been described. SEM calibration methods, including measurement of the magnification and diameter of the electron probe, have been developed on the basis of this model. Real structure line width measurement methods have been developed allowing measurements of down to 50 nm.
Proc. SPIE 6260, Simultaneous fitting of several x-ray rocking curves from different crystallographic planes of multilayer heterostructures, 626014 (10 June 2006); doi: 10.1117/12.683399
A general mathematical approach is realized for simultaneous treatment of several X-ray rocking curves from different crystallographic planes. The corresponding analysis of experimental X-ray rocking curves for (004), (113) and (115) reflections from the single quantum well GaAs-InxGa1-xAs/GaAs(001) heterostructure have been carried out. This approach allows one to restore the depth profiles of the lattice mismatch and mean-square displacements of atoms from regular positions for particular layers as well as to estimate the anisotropy of in-plane and normal-to-plane random atom displacements.
A method has been suggested for measuring the line width of trapezoidal profile relief elements on a scanning electron microscope (SEM) for cases where the electron probe diameter is greater than the measured size. The method has been demonstrated on low voltage SEM. The minimum size that could be measured was 13 nm, which is almost in 2 times smaller than the low voltage SEM electron probe diameter.
Proc. SPIE 6260, Structural and nonlinear-optical studies of ultrathin Si/Si0<sub>2</sub> multiple quantum wells, 626016 (10 June 2006); doi: 10.1117/12.683402
Optical second harmonic generation (SHG) in amorphous Si/SiO2 multiple quantum wells (MQW) is studied by means of SHG spectroscopy, SHG interferometric spectroscopy and X-ray double-axes reflectometry of the MQW samples with the Si quantum well thickness d ranging from 1.00 to 0.25 nm. The electron density profiles obtained from X-ray reflectometry data confirm multilayer structure presence and refine growth data on d values. The observed modification of the SHG spectra upon decreasing d is interpreted using combination of the resonant two-subband approximation for the nonlocal optical response of each quantum well with the generalized transfer-matrix formalism for the description of light propagation across the whole MQW structure. Agreement with the experiment shows that the description of the quadratic optical response of the MQW structure within the model of a nonlocal piecewise-continuous medium remains valid on the sub-nanometer scale.
The DLTS and admittance measurements were performed on the MOS and Schottky diodes formed on the strained-Si/SiGe/Si heterostructures. Several DLTS features were observed and analyzed, and properties of the peculiar Dl peak were studied in detail. Temperature dependence of the SiGe layer conductivity was extracted from the C(T) and G(T) curves. The analysis of ability of the DLTS technique to detect defects in the thin top layer is given.
Proc. SPIE 6260, Photoluminescence of 2D electronic epsilon-layers in lateral non-homogeneous nano-structures based on GaAs, 626018 (10 June 2006); doi: 10.1117/12.683405
Within the framework of previously proposed the spectral-correlative method investigation of the semiconductor structures with laterally nonuniform layers the photoluminescence (PL) of the structure on basis GaAs with n-type d-layers at 77 K is investigated. This method has allowed to study on one sample the dependence of the features of observed multicomponent spectrum PL from a variation of two parameters - distances between d-layers and composition of the narrow quantum well InGaAs taking place between them. The obtained results allow to link observed exponential increase of the intensity PL from the area of the d-layers at change these parameters with change of a ratio of the lateral located in minima of the fluctuation potential and free two-dimensional holes. The effect of the stabilization of the energetic position of PL spectral lines which we associate to the localization of the holes in a potential well between d-layers was found out. The received experimental results coordinated with the numerical calculations carried out in our work.
Proc. SPIE 6260, Rearrangement of resonant-tunneling structure in the electric field revealed by complementary photoluminescence and vertical transport characterization of the GaAs/AlGaAs long-period superlattices, 626019 (10 June 2006); doi: 10.1117/12.683465
Multi quantum-well long-period structures are promising for a number of important applications including the far infrared intersubband-transition-based narrow-band radiation devices, microwave resonant-tunneling and self-sustained current oscillation generators, multilevel-logic element devices based on the recently found switching effect between the multistable current states, terahertz emission detectors. All devices have in common the operation dependence on resonant-tunneling rearrangement effects in the long-period structure. We present the results of optical investigation of
resonant-tunneling rearrangement processes in long-period GaAs/AlGaAs superlattice structures under application of vertical electric field by means of low-temperature photoluminescence (PL) technique in comparisons with the data of vertical transport measurements performed simultaneously on the same structures. The effect of appearance of the new PL peaks accompanied by suppression of the old ones with increasing bias voltage has been detected, resulting from the Stark shift phenomenon. PL intensity dependences on the applied voltage are presented for the first time which complement the measured current-voltage data. The transition effect from bound (exciton) to free (electron and hole) states in electric field is observed. It is shown that the optical research method can be more sensitive in some situations to provide the crucial information about the resonant-tunneling rearrangement effects even under condition when the ordinary current-voltage measurements do not reveal any features.
Proc. SPIE 6260, The surface roughness investigation by the atomic force microscopy, x-ray scattering, and light scattering, 62601A (10 June 2006); doi: 10.1117/12.683482
Roughness investigation of the polished quartz and sital substrates, used as substrates for multilayer interference mirrors in circle laser gyroscopes, were carried out. Atomic force microscopy, x-ray scattering and angle-resolved scattering instruments were used. The power spectral density function and effective rms roughness were calculated. Good correlation of power spectral density functions and effective rms roughness was shown for all instruments. Essentially difference of the polishing quality was shown for sital substrates manufactured by two different producers.
A novel type of X-band transmit-receive switch is proposed that is based on a PHEMT-controlled stub directional coupler. The operation of the switch is analyzed. The impedances of the stubs are optimized to yield a considerably larger bandwidth of the switch. It is shown that the circuit can serve as a building block for multi-channel switches.
Physical bases of the electroforming phenomenon are described in view of conceptions developed about it during last years as the process of self-formation of a nanometer insulating gap in a conductive medium which is formed on a dielectric surface in some general enough conditions. The structure and the characteristics of a cell of non-volatile electrically reprogrammable memory made by methods of silicon technology and based on the phenomenon of electroforming in open Si-SiO2-W "sandwich"-structures with thickness of silicon dioxide about 20 nm is given. The information in such memory is coded by the sizes (and resistance) of a self-forming conducting nanostructure, therefore already from physical principles it should possess the high thermal and radiation resistance that is confirmed experimentally. On the made samples of a small capacity matrix (3×3 cells) all the functions of non-volatile electrically reprogrammable memory have been shown.
Single-crystal silicon is an ideal material for packages. Moreover, it has the same temperature coefficient of expansion as a chip. Silicon has high thermal conductivity and low dielectric penetrability. It also has excellent mechanical properties. In addition, recent trends in engineering literature indicate a growing interest in the use of silicon as a mechanical material. We have developed a design and fabrication technology of SBGA packages. The SBGA package consists of silicon substrate with ball leads arranged under the package base in several rows. A main problem with such a package is a formation of feedthroughs in the silicon substrate. The feedthroughs can be fabricated by means of the aluminum thermomigration (temperature gradient zone melting) method. The thermomigration process is due to dissolution of silicon atoms on the hot side of the molten zone, the transport of the atoms across the zone, and their deposition on the cold side of the zone. We fabricated SBGA carrier which has 0.2×0.2 mm sizes of the feedthroughs and 1.27 mm pitch footprint. The SBGA package has peripheral ball array. Package sizes have 25×25 mm and 576 ball leads. A resistance 0.4 mm length of the feedthrough is equal to 0.5 Ω. The parasitic capacitance is also quite small. In the case 1000 Ω-cm silicon, a parasitic capacitance is only 2.0 pF. Taking this values of 0.5 Ω and 2.0 pF, then we see that the RC time constant of a typical feedthrough is on the order of 1.0 ps.
Proc. SPIE 6260, Calculation of secondary charge carrier current in submicron channel MOSFETs at stress regimes of operation, 62601E (10 June 2006); doi: 10.1117/12.683488
The Monte Carlo model of the impact ionization in deep submicron MOSFETs is worked out. This model allows the influence of the secondary charge carrier current on the drain current to be evaluated. The developed model is built on the basis of the reduction scheme. Moreover, the model takes into account all the major features of electron transport in deep submicron MOSFETs, the dominant scattering mechanisms, the quantization of electron spectrum as well as the modeling of constructive parameters and basic drain breakdown mechanisms.
A new electric circuit layout and physical structure are proposed for an element of protection against electrostatic discharges. The new element features twice as small resistance to the electrostatic discharge current. The reduced resistance is obtained by using additional transistors implementing feedback. The use of the new electric circuit layout and of a new simulation technique that takes into account substrate transistors made it possible to reduce the element's area 1.5-fold and its electric capacity 1.6-fold.
(BMT) with well. Investigation by the modem two-dimensional TCAD of the volume SRH-recombination are studied of the lateral bipolar magnetotransistor with the diffusion well for the physicists of working and high sensitivity designs. Magnetic field effect create volume concentration-recombination mechanism of the current negative sensitivity. For raising sensitivity is conduct study of series lateral bipolar magnetotransistor with base in well. Joining the contacts of base and well creates a threshold of operating, negative magnetosensitivity, growing of sensitivity in weak magnetic field. Transistor can serve the generator electron-hole plasma. Device has volumetric generation-recombination mechanism of sensitivity, new principle of getting maximum relative sensitivity on the current 2000 1/T in the magnetic field of the Earth.
Proc. SPIE 6260, Combined method of copper electroplating deposition and low temperature melting for damascene technology, 62601H (10 June 2006); doi: 10.1117/12.683493
The combined method of trench filling by copper for damascene technology has been developed. The method is based on copper deposition by ordinary electroplating and following low temperature melting of copper layer. The thickness of wetting layer has been optimized. The importance of seed layer surface treatment is demonstrated. It is shown that the thermal annealing at 650oC allows to dispose of voids appearing at copper electrochemical deposition into trenches.
Proc. SPIE 6260, An automatic synthesis method of compact models of integrated circuit devices based on equivalent circuits, 62601I (10 June 2006); doi: 10.1117/12.683496
An automatic synthesis method of equivalent circuits of integrated circuit devices is described in the paper. This method is based on a physical approach to construction of finite-difference approximation to basic equations of semiconductor device physics. It allows to synthesize compact equivalent circuits of different devices automatically as alternative to, for example, sufficiently formal BSIM2 and BSIM3 models used in circuit simulation programs of SPICE type. The method is one of possible variants of general methodology for automatic synthesis of compact equivalent circuits of almost arbitrary devices and circuit-type structures of micro- and nanoelecronics [1]. The method is easily extended in the case of necessity to account thermal effects in integrated circuits. It was shown that its application would be especially perspective for analysis of integrated circuit fragments as a whole and for identification of significant collective physical effects, including parasitic effects in VLSI and ULSI. In the paper the examples illustrating possibilities of the method for automatic synthesis of compact equivalent circuits of some of semiconductor devices and integrated circuit devices are considered. Special attention is given to examples of integrated circuit devices for coarse grids of spatial discretization (less than 10 nodes).
MOSFET analyzer is developed to extract most important parameters of transistors. Instead of routine DC transfer and output characteristics, analyzer provides an evaluation of interface states density by applying charge pumping technique. There are two features that outperform the analyzer among similar products of other vendors. It is compact (100 × 80 × 50 mm3 in dimensions) and lightweight (< 200 gram) instrument with ultra low power supply (< 2.5 W). The analyzer operates under control of IBM PC by means of USB interface that simultaneously provides power supply. Owing to the USB-compatible microcontroller as the basic element, designed analyzer offers cost-effective solution for diverse applications. The enclosed software runs under Windows 98/2000/XP operating systems, it has convenient graphical interface simplifying measurements for untrained user. Operational characteristics of analyzer are as follows: gate and drain output voltage within limits of ±10V; measuring current range of 1pA ÷ 10 mA; lowest limit of interface states density characterization of ~109 cm-2 • eV-1. The instrument was designed on the base of component parts from CYPRESS and ANALOG DEVICES (USA).