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Using two-temperature synthesis method with the further directed crystallization under the radial and slight horizontal temperature gradients, facilitating the convection and mixing of the melt, the authors obtained monocrystals of n- and p-[CuInSe.sub.2] with controlled deviation from the stoichiometry using the excess In and Se. We have carried out the measurements of the conductivity and Hall coefficient in the temperature interval 70-415 K and investigated Hall mobility as the function of temperature, determining the dominating carrier scattering mechanisms. It was found that the electrical properties of n- and p-[CuInSe.sub.2] are caused by the defects of various types depending on the growth conditions and stoichiometry deviations. The energy position of the impurity levels was identified to be 0.055 [+ or -] 0.003 eV and 0.022 [+ or -] 0.003 eV above the valence band for acceptor levels and 0.010 [+ or -] 0.002 eV below the conduction band for the donor level. Keywords: [CuInSe.sub.2] monocrystals; Directed crystallization: Mobility; Scattering mechanisms; Impurity levels

Several electrical in situ and ex situ measurements are conducted to study the influence of various environmental conditions, like dry oxygen and moisture on the electronic transport and device stability of the polycrystalline pentacene transistors. The analysis reveals that such conditions inhibits the injection of holes in the highest occupied molecular orbital level of the film, which further leads to an apparent reduction of the charge carrier mobility, as well as the threshold voltage.

The redistribution profiles of ion-implanted impurities during solid-phase epitaxy (SPE) are evaluated by using Rutherford backscattering spectrometry (RBS) and an analytical model is derived for these redistribution profiles. The model can be used to predict the impurity redistribution profiles after SPE, which can be used for the subsequent diffusion process.

The deep level defects in annealed InP are investigated by using photoluminescence (PL) spectroscopy, thermally stimulated current (TSC), deep level transient spectroscopy (DLTS) and positron annihilation lifetime (PAL). The results have identified the divacancy defect, its related PL emission and trap level.

The steady state Shockley-Read-Hall kinetics are used to study the effects of energy distributions of Si/Si[O.sub.2] interface traps in the energy gap oxidized silicon on the current versus voltage line shape of the electron-hole recombination current. It is concluded that the electron-hole traps at the Si/Si[O.sub.2] interface are more likely to have a U-shaped DOS than discrete few-level interface traps around the Si midgap.

The Si:H network was characterized during transformation from amorphous to micro- and nanocrystalline structures aided by increasing [H.sub.2] dilution to the Si[H.sub.4] ensemble in hot-wire chemical vapor deposition (HWCVD). The elevated [H.sub.2] dilution induced enormous polyhydrogenation and formation of lesser sense network full of voids, mostly around the tiny micro/nanocrystallites.

The effect of H doping in combination with various thermomechanical treatments given to materials, in order to identify conditions for maximum efficiency in the conversion of mechanical energy into heat at around room temperature was studied. It was observed that for appropriate alloy composition, the peaks occur at around room temperature (for acoustical frequencies), providing an opportunity to reduce machinery vibrations and noise pollutions.

The F control of the point defect density in preamorphized Si layers is studied by investigating the F incorporation process during the solid phase epitaxy (SPE) of amorphous Si layers. The results have demonstrated F to be a versatile and powerful tool to control the point defect density in Si, acting as a trap for the Is and indirectly modifying the diffusivity of dopants.

High-resolution x-ray scattering is used to study the effect of hydrogen implantation in silicon single crystals. The results have shown that a slight annealing required to form localized defects induces a strong reduction of the average strain level in the implanted crystal.

A novel self-aligned fully silicided (FUSI) gate process for the integration of platinum monosilicide (PtSi) as a metal gate for pMOS applications is described. The correlation between the work function shift caused by the segregated impurities at the gate/dielectric interface and the atomic size and surface dipole can be explained by the variation of the surface dipole, placing the impurity atoms exactly at the gate/dielectric interface.

Erbium-doped Si[O.sub.2] toroidal microcavity lasers are fabricated on a Si substrate using a combination of optical lithography, etching, Er ion implantation, and C[O.sub.2] laser reflow. Three-dimensional infrared confocal photoluminescence spectroscopy imaging is used to determine the spatial distribution of optically active Er ions in the two types of microtoroids, and distinct differences are found.

The microstructural evolution occurring within the eutectic SnPb solder during electromigration is investigated utilizing Blech specimens. Three-dimensional simulation is performed to examine the change in resistance and current-density distribution during electromigration.

CdGeAs2 crystals typically exhibit an absorption band near 5.5 mum that limits their use as a nonlinear frequency-conversion material in high-power infrared laser systems and this absorption band is related to the p-type nature of the as-grown bulk crystals. The variation in activation energy is correlated with p, and also with N(sub A) and finds excellent agreement with theory.

A methodology for extracting between the source and drain the spatial variations of surface dopant-impurity concentration and oxide thickness in the channel drain/extension and source/extension regions are described. The experimental tunnel direct current current-voltage data of the drain source and basewell terminal currents versus the gate/base voltage are used.

Complete gate silicidation is an excellent technique for the integration of metal gates into MOSFETs, and NiSi is the most scalable silicide gate material. A versatile method, which relies on doping the poly-Si with various impurities prior to silicidation, for controlling the workfunction of a NiSi gate is presented.

The electronic structure of a hydrogenic impurity atom located at the center of a multilayer coated quantum dot (CQD) is investigated. The electronic eigenstates of the CQD system are expressed in terms of the geometry and the material parameters by solving the Schrodinger equations analytically.

A theoretical investigation is performed on the properties of iron-acceptor impurity pairs (Fe-A, with A=B, Al, Ga, and In) in silicon. The results are found to be in good agreement with the experimental trends among the Fe-A pairs, describing the increase in the pair donor energy level with increasing A principal quantum number and decreasing pair separation distance, and the pair configurational symmetries.

The scalability of bulk complementary metal-oxide semiconductors (CMOS), and the feasibility of intrinsic channel silicon-on-insulator (IC-SOI) CMOS, instead of the bulk, are examined with regard to threshold voltage (V[subscript TH]) fluctuations.

Parallelepiped-shaped GaAs-(Ga,AI)As quantum dots were investigated to determine the effects of uniaxial stress on binding energies of shallow donor impurities.

Research describing the influence of impurities on the electronic properties of hole transport layers is presented. Trap levels, transport properties and luminescence of organic light emitting devices are examined.

Research describing the effects of ion fluence on interfacial intermixing and surface smoothing of multilayered thin films is presented. In particular a nickel-copper-nickel multilayer system is investigated.

A method to characterize deep impurities in semiconductors using tunneling ionization in high frequency fields, is presented.

The carrier freeze-out, responsible for a kink effect in MIS capacitance-voltage, is examined.

Two-dimensional energy transport simulations were used to study a 0.18 Mum nMOS structure with a vertically nonuniform low-impurity-density channel.

The authors examine methods to improve optical absorption using back illumination. Topic include oscillators, transducers, and drain-sources.

Reserach was conducted to measure the effect of an electric field applied along the direction of carrier confinement on the exciton linewidth due to the scattering of excitons by ionized impurities in semiconducting quantum well structures. It was found that the contributions to the linewidth increased with the applied electric field except for the narrowest wells. Also, the contribution to the linewidth due to elastic scattering of the exciton is many orders of magnitude larger than that due to scattering in which the exciton is ionized.

Research was conducted to examine the modeling of the liquid aluminum layer method for the gettering of metallic impurities in multicrystalline Si wafers. The impurity atom diffusion and segregation processes and the precipitate dissolution process were included in the modeled aspects. Gettering results were analyzed via a relative integrated recombination constant that accounts for minority carrier recombination events at both precipitates and at individual dissolved impurity atoms throughout the Si wafer.

Research was conducted to examine the behavior of particles in plasmas laser Doppler velocimetry (LDV) using LDV as an alternative to laser light scattering. The study focused on the characterization of the dynamics of particles that display local trapping. Experimental results are compared with laser light scatter which is often used for studying particle dynamics. In an attempt to interpret the experimental results, various theories are reviewed.

Research was conducted to examine the impact of iodide impurity on silver cluster formation on AgBr microcrystals using a computer simulation model. One advantage of the use of the computer simulation model is that potential inefficiencies could be studied individually. The efficiency of the silver cluster formation was observed to be a function of microcrystal size and revealed to increase with size for the impurity-free control, contrary to experimental data.

Research was conducted to examine the electrical conduction in an n-type In0.53Ga0.47As/InP sample developed by molecular beam epitaxy in the magnetic field of up to 1.5 T and with temperatures ranging from 15 to 295 K. The negative magnetoresistance in the impurity band was described by carriers with the constant concentration and the mobility increasing proportionally to the square of the applied magnetic field. Results demonstrate that the mobility spectrum technique is useful in the analysis of negative magnetoresistance.

A study was conducted to analyze the segregation of a number of metal impurities in silicon under low-energy oxygen ion bombardment. n-type Cz silicon wafers supporting resistivity betwee 1 to 10 ohms-cm and (100) orientation were utilized. Results indicated that the segregation of calcium, chromium and tantalum at the SiO2/Si interface and the antisegregation of titanium, Hf and zirconium into the oxide were influenced thermodynamically.

Research was conducted to examine the crystalline silicon p-n junction solar cells containing a high density of In impurities. The continuity equations for electrons, holes and defect levels and the numerical resolution of Poisson's equation generates the current-voltage curves for several impurity concentrations. Results demonstrate that an increase of the short-circuit current densities of up to 6 mA/cm2 can be derived with the highest In impurity concentration. However, this results in the reduction of the open-circuit voltage and of the energy conversion efficiency.

A model is derived to analyze the capacitance-transient phenomenon in an metal-insulator-metal system with the presence of a space charge in the insulator. The trap parameters in an insulator are determined based on the transient behavior of the capacitance as a function of the applied voltage and temperature. This capacitance transient spectroscopy was then used to characterize traps in polyimide films. Good agreement was obtained between experimental and theoretical results.

The role of silicon impurities as hole traps in KTiOPO4 crystals is investigated using electron paramagnetic resonance. This center is formed when crystals are exposed to either 60 kV x rays or pulsed 355 laser beam. It is shown that the silicon-associated hole centers decay at room temperature due to the release of electrons from the Ti(super 3+) centers. The kinetics of the electron-release process are also second-order. A theoretical model for the hole center is derived.

Research was conducted to examine the two new infrared absorption bands related to interstitial oxygen (Oi) in silicon crystals. Studies performed on their oxygen isotope shift and temperature dependence were used in the assignment of the bands at 560 and 648 cm(super -1). Results demonstrate that the bands exhibited a strong temperature dependence in their intensity. the 560 cm(super -1) band was observable at room temperature and gradually disappeared as temperature decreased while the 648 cm(super -1) band was detectable at low temperatures only.

Research was conducted to examine the hypothesis that impurities in MeV-implanted and annealed silicon may be trapped at interstitial defects near the projected ion range and at vacancy-related defects. The temperature dependence of impurity trapping was investigated by annealing the samples twice. Results indicate that the trapping of intrinsic oxygen at both types of defects has no significant influence on the trapping of metallic impurities at extrinsic dislocations.

Research was conducted to examine the effects of impurity states associated with heterostructures on the absorption of ultrasound. The objective of the study was to set up a calculation for the photostimulated ultrasound absorption by acceptor impurities in GaAs/Ga(sub 1-x)Al(sub x)As quantum wells. Results demonstrate that any device made from quantum well systems can be utilized as efficient traveling-wave detectors for ultrasound.

Variations in dopant concentrations and their role on the transient behavior of silicon avalanche shaper (SAS) devices have been studied. SAS devices are semiconductor switching devices used in high-power waveform shaping applications. A mathematical model which takes into account the influence of impact ionization, carrier trapping and generation, bipolar flow has been developed to carry out the study. Results show the presence of an electric wave field from the cathode to the anode. There were no filamentary currents due to the absence of transverse variations.

A unified closed form model for the base transit time for uniform and nonuniform base doping distributions in silicon-germanium heterojunction bipolar transistors (SiGe HBT) has been derived. It is used in investigating the design of Ge layers for various base doping profiles. A false minimum appears in the value of the base transit time when it is plotted against X(sub T) if the constant film stability has not been accounted for. Values obtained with the use of the model agree with previously published results.

The activation energy and capture cross section of traps found in gallium-arsenide field-effect transistors (GaAsFET) have been measured. These values have been derived using transient, frequency dispersion and noise spectroscopy. The GaAsFET studied has been biased in current saturation which is the normal bias for these devices. Results show that the various spectroscopic methods used in obtaining the trap parameters give similar results with no significant deviations. The deep-level transient spectroscopy gave the biggest signal and found the most traps.

The influence of electric fields on the states of a donor impurity in rectangular cross-section vacuum/GaAs/vacuum quantum-well wires was investigated using effective mass approximations within a variational approach. The results revealed that applied electric fields decompose the degeneracy of the states for impurities symmetrically positioned within the structure. Moreover, the electric field and geometric configuration were indicators of the presence of bound excited states.

The filamentary model of the metal-insulator transition in randomly doped semiconductor impurity bands is geometrically equivalent to similar models for continuous transitions in dilute antiferromagnets and even to the A transition in liquid He, but the critical behaviors are different. The origin of these differences lies in two factors: quantum statistics and the presence of long range Coulomb forces on both sides of the transition in the electrical case. In the latter case, in addition to the main transition, there are two satellite transitions associated with disappearance of the filamentary structure in both insulating and metallic phases. These two satellite transitions were first identified by Fritzsche in 1958, and their physical origin is explained here in geometrical and topological terms that facilitate calculation of critical exponents.

A novel technique based on laser-induced transient grating method was used to examine deep levels in n-InSb and n-HgCdTe. The approach was able to locate deep levels with an accuracy of approximately 0.2 meV. Compared to the magneto-optical method of detection, the noncontact technique is simpler and very responsive to variations in the complex refractive index of the material. It is a direct approach to locating the presence of defects and impurities.

Research was conducted to examine the atomistic modeling of high-concentration effects of impurity diffusion in silicon on a microscopic model level. The microscopic forces between dopant atoms and vacancies are taken into consideration in performing the simulation. Simulation results for the different microscopic approaches are utilized to give an evaluation of the validity of models for high-concentration diffusion based on percolation theory.

Research was conducted to investigate the atomistic analysis of the vacancy mechanism of impurity diffusion in silicon. Measurement was performed from the atomistic mechanism through accurately taking into consideration the effects of the microscopic forces between vacancies and dopants. Results indicate that the reduction of the activation energy of dopant diffusivity can be explained by a nonbinding interaction that enlarges the vacancy mobility in the neighborhood of the dopant.

Research was conducted to examine the fourfold coordinate nature of N in chemical vapor deposited (CVD) diamond and tetrahedral amorphous carbon (ta-C). Measurements were based on a combination of density-functional methods at several levels of approximation used on supercell and cluster models. Results reveal that when the Fermi level, Ef falls below A1, N doping charge is transferred to the available deeper lying states.

A study was conducted on the effects of doping element on n-silicon electron mobility at low electric fields. The Thomas-Fermi theory employing the energy functional formulation was used to compute the electron charge distribution of impurities. Results, which were compatible with experimental data, verify the As-doped silicon lower electron mobility as compared to P-doped silicon.

State-of-the-art density functional calculations were employed in examining the structural and electronic properties of the defect tetrahedral semiconductor Ga2Se3 with ordered vacant sites. Vacant sites ordered in a monoclinic structure exhibited no significant differences. The importance of considering the presence of vacancies and atomic scale relaxations and the avoidance of virtual crystal approximation were stressed.

Research was conducted to examine the effects of atomic bond structure at the deposition surface on the crystallographic orientation dependence of carbon doping in gallium arsenide (GaAs). GaAs epilayers were prepared from semi-insulating GaAs substrates by atmospheric pressure in a vertical quartz reactor while epitaxial growths were carried out on different misoriented GaAs substrates. Results indicated CBr4 and CCl4 as excellent sources for the carbon doping of GaAs.