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A model of amorphous layer thickness formed by ion implantation with an arbitrary tilt angle is presented. Findings reveal the insensitivity of the through dose to the tilt angle.

The analysis of the contact resistance in gallium-indium-zinc-oxide (GIZO)-based thin-film transistors (TFTs) with different source/drain electrodes is discussed. Highest field-effect mobility is observed in case of Ti/Au.

The dynamic behavior of a 3-TFT current programmed pixel is examined and the impact of V(sub TH) shift on the organic light-emitting diode (OLED) drive current is analyzed. The pixel circuit was implemented in amorphous silicon technology and lifetime tests show an 11% current degradation at 700 h.

The design, fabrication process, and performance evaluation of a two-dimensional hydrogenated amorphous silicon (a-Si: H) n-i-p photodiode array, developed specifically for low-level light sensor applications is presented. The optical losses in the photodiodes with an ITO/a-SiN(sub x):H antireflection coating is minimized using numerical modeling.

A study was conducted to measure the vibrational OH-stretch spectra of large water clusters with photofragment spectroscopy after the absorption of pulsed tunable infrared radiation in the frequency range from 3000 to 3800 cm(super -1). The results revealed that the method is mainly sensitive to the outer cluster surface, which has for all sizes an amorphous structure dominated by 3-coordinated, and to a lesser extent also by 4-coordinated molecules.

Photodegradation behavior of a-Si:H photodiodes is examined with regard to dark-current density, electron micro-gamma product and transient photocurrent. Degradation occurs because of light-induced defects in the a-Si:H layer.

Electrical instability of amorphous thin-film transistors manifests as a shift in threshold voltage after long-time application of gate voltage. The formulation of this shift is given as a function of temperature , time, and gate voltage.

Leakage currents of amorphous silicon thin film transistors were studied in the context of stress effects, injection and back channel currents.

Leakage currents of amorphous silicon thin film transistors were studied.

A study investigated the properties of three-terminal, three-color a-SiC:H/a-Si:H-based TCO/PINIP/TCO/PIN/metal detector assemblies with a focus on the optical and transient behavior organization. Different TCO/PINIP/TCO/PIN/metal detector assemblies featuring different TCO surface properties were compared in terms of steady-state properties, advantages and disadvantages. Experimental methodology, results and conclusions are discussed.

Sol-gel materials, including glass, noncrystalline solids and ceramics, have been found to manifest strong dielectric behavior when exposed to relatively low temperatures. Such a phenomenon may be attributed to the random motion of ions found in mobile molecules and those which are integrated into the residual groups within the matrix. Dielectric response data derived from sol-gel glass samples further revealed that the dielectric relaxation response may be used to determine the porosity and fractal dimensions of these materials.

A comparison of simulated and experimentally determined spectral response data was performed to analyze the optoelectronic properties of novel p-i-i-i-n color sensors. Simulation findings showed the strong correlation between optical absorption in the individual layers and the voltage controlled spectral response. These also revealed the influence of additional bias light on color separation due to recharging of defect states. A deconvolution method which allowed the transformation of the measured spectral response curves into a red-green-blue signal was given.

The impact of extended heat treatment on the metal induced lateral crystallization (MILC) rate of amorphous silicon (a-Si) is studied using transmission electron microscopy and orientation image microscopy. Results show that extended heat treatment reduces the MILC rate possibly due to the constantly changing state of the a-Si and decreasing Ni from the Ni covered area. MILC length also increased with the radii of the Ni disc patterns with the longest MILC lengths generated by straight-edged Ni patterns due to their infinite radii of curvature.

A study was conducted to analyze the electrical characteristics of a two-level system in two-polymer glasses. Two types of polymers were examined, namely polymethylmethacrylate and polystyrene. The time evolution of a spectral hole was also analized in an electric field cycling experiment. Results indicated that the time evolution of the field-induced spectral diffusion correlated qualitatively with model predictions.

A study was conducted to analyze the microstructural characteristics of amorphous MoO3 thin films colored by injection of various cations using Raman microscopy. The thin films were obtained by the vacuum deposition of high-purity MoO3. Results indicated that the coloration means affected the microstructure of molybdenum bronze. In addition, the size of the cations through electrochromic processes had negligible effect on the microstructure of the films.

A study was conducted relating to research on the synthesis, characterization of both optical/chemical properties and application of colloidal, quantum dot, semiconductor materials. The experiment describes the third-order nonlinear optical response of a prototypical nanocomposite 'nonlinear-nonlinear,' optical polymer consisting of thiopenol-capped cadmium sulfide quantum dots embedded in a L - B multilayer film of polydiacetylene alloy.

The density of states (DOS) in the conduction channel for nonpassivated devices before and after bias stress is analyzed by using 2-D simulations and activation energy measurements of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFT). Results showed that increases in DOS directly affect the subthreshold slope and capacitance dispersion and activation energies obtained before and after the bias stress show the increase in the DOS over particular energy ranges and agree well with 2-D simulations.

A study was conducted to determine the transient behavior of an amorphous silicon based nipiin two-terminal device with a good color separation and a high dynamic behavior. In comparing the measured and simulated transient response after bias voltage switching, it is revealed that the delay time of the photocurrent depends on the capacitance of the top and bottom diode as well as on the applied light intensity.

A two-terminal hydrogenated amorphous silicon device with bistable current-voltage features has been simulated to create a novel switch and memory mechanism for large area application. The solid-state crystalline device has an a-Si:H multilayer stacked structure and negative differential resistance. Device realization was established at stitching voltages of between 12 volts and 15 volts.

Research shows that pixel-switching thin-film transistors perform less flexibly when the thickness of the a- Si:H layer is reduced to 0.05 micrometers. Source-gated photo-transistors work over 30 times the dynamic range of pixel-switching thin-film transistors at the same a-Si:H layer thickness by increasing the illumination current of the device.

Organic thin-film transistors (TFTs) with the fused-ring polycyclic aromatic hydrocarbon pentacene as the active electronic material have exhibited mobility as much as 0.7 cm2/V-s and on/off current ratio larger than 10(super 8). These values were comparable to hydrogenated amorphous silicon devices. However, these TFTs exhibit undesirably large subthreshold slope, which is not an intrinsic property of the organic semiconducting material.

A selective excimer-laser crystallization technique enables the fabrication of high mobility short-channel amorphous-silicon thin-film transistors with submicrometer-long bottom-gate. Both the parasitic resistance and the parasitic capacitance can be reduced significantly in these devices. This is possible because the highly conductive source and drain of n poly-Si are formed in a self-aligned manner with the gate electrode.

An amorphous silicon-based n-i-p-i-n three-color sensor shows color sensitivity on application of bias voltage, varying between -2 and +2 volts. The sensor is very useful in the integration of a color sensor on the top of an ASIC chip. Optimization of film thickness and the optical band gap of each layer provides maximum color separation. Performance of the sensor depends on the roughness of the surface of metal-back. A three times reduction of the dark current at high voltages enhances the dynamic range by 60 dB.

An n-type ta-C/p-type Si-heterojunction is fabricated successfully using a low temperature filtered-cathodic vacuum-arc deposition process. The heterojunctions are sharp and abrupt. The complete band diagram of this heterojunction reveals the electron affinity of the ta-C and the current-transport mechanism of the junction.

Addition of silicon barrier enhancement layers to a-Si:H/a-SiC:H double barrier structure results in a negative differential resistance current/voltage curve having a high peak-to-valley ratio. The addition is done in the collecting and injecting diode regions. The enhancement layers reduce leakage current and increase resonant tunneling current, and are more effective than crystalline AlGaAs/GaAs double barrier diodes. A primary model simulating these data account for the validity of enhancement layers.

The growing filament radius (GFR), the fixed filament radius (FFR) and the limited power supply (LPS) models were used for evaluating the final resistance and formation of filaments in the vertical programmable element of amorphous-silicon. The GFR and FFR models operate under assumptions of constant current and Joule heating requirements the for formation of filaments, while the LPS is modeled on restricted electric power supply during forming. The filament development is monitored by the GFR model. The signficance of the external circuitry to the process of formation of films is revealed by the LPS model.

Waveguide modulators incorporating parallel-plate electrodes are investigated by computer modeling. Metal-electrode structures differ from severe optical losses that are due to surface plasmons. Silicon-electrode structures exhibit lower losses. Bandwidth is limited by the resistivity and the proximity of the electrodes. Doping the silicon improves conductivity but increases optical absorption. Device optimization involves a trade-off between bandwidth and optical loss. Devices are fabricated by the use of substrates of silicon on sapphire, with rf sputtered lithium niobate films and plasma-enhanced chemical vapor-deposited hydrogenated amorphous silicon for the upper electrodes. The electro-optic coefficient of these lithium niobate films is approximately 50% of the value for bulk material. The results indicate the possibility of using these devices for combining silicon integrated circuits with waveguide modulators on a common substrate.

A proposed design for a high-gain amorphous silicon/amorphous silicon germanium bulk barrier phototransistor for infrared light detection is presented. Results show that high gain is generated by large bulk barrier lowering in situations of light illumination and dark current retardation. Also, the introduction of an additional amorphous silicon carbide thin-film layer at the base and collector interface.

The fabrication, structure and performance of a proposed silicon high-voltage thin-film transistor (HVTFT) and its uses in electrographic plotting is discussed. Results show that instabilities in relation to a specific parameter are generated by local high state density and can be controlled by the HVTFT's structure. Adding a positively biased field plate also significantly reduces these instabilities.

Optical properties of amorphous semiconductor films are usually strongly dependent on deposition conditions. To the best of our knowledge, this is the first publication on optical properties of amorphous Ge films that are grown by laser-assisted deposition and measured by means of spectroscopic ellipsometry over a wide spectral range (1.43-4.59 eV). Optical properties of dc magnetron-sputtered and e-beam-deposited films are also included. Effective medium modeling is used to analyze the void fraction and the film homogeneity through the thickness. The results show that laser-deposited films and dc magnetron-sputtered films are similar, both being denser, more homogenous, and more stable than e-beam-deposited films. Transmission electron microscopy analysis shows that the results of the optical study are correlated to the film structure. These results are discussed in terms of the kinetic energy of the species involved in each deposition technique and some conclusions related to the laser-assisted deposition process are reported.

Analytical and experimental results that show novelty filtering, optical phase conjugation, and real-time edge enhancement by using optically addressed spatial light modulators that comprise amorphous silicon photodiodes and analog and binary ferroelectric liquid-crystal modulators are presented. The advantages of these devices for the above applications include high-speed, low-power operation and high spatial resolution.

We discuss the use of hydrogenated amorphous silicon (a-Si:H) photodiodes as photosensors in high-performance optically addressed spatial light modulators (OASLM's). To find the performance limitations that result from the photodiode exclusively, a pseudo-OASLM is constructed; it is composed of an a-Si:H photodiode in series with a discrete capacitor and resistor to simulate an electrically ideal liquid-crystal modulator. The a-Si:H photodiode conduction regimes are identified, and the maximum and minimum frame rates that may be attained with an a-Si:H photodiode-driven OASLM are determined to be 100 kHz and 0 Hz, respectively. Optimum performance is obtained when the photodiode capacitance is equal to the light modulator capacitance.

A new model for characterizing the static and dynamic behavior of amorphous silicon thin film transistors is introduced. The model, which was recently included in the SPICE circuit simulation software, is based on the assumption that the deep states and the tail states have an exponential distribution. It considers other parasitic effects while correlating the localized states's concentration and temperature to the current-voltage characteristics of the device.

The design, fabrication and characteristics of a heterojunction p-i-n diode is presented. The diode, which was developed for ultraviolet detection implementation without any external bias, exhibits low noise and a 200% rise in responsitivity over the Schottky photodiode for the 200-400-nm wavelength range. Its enhanced performance may be attributed to the use of an amorphous front layer with a decreased thickness and low-level phosphorus doping of the layer.

An experiment was conducted to measure the photodegradation of a hydrogenated amorphous photoconversion layer on a solid-state image sensor. It focused on such light triggered effects as sensitivity, residual current and dark current. The former was found to be responsible for the layer's lifetime together with the space charge density. The latter provided the measure of the layer's lifetime which was found to be 1.5 x 10 to the seventh power under normal light intensity.

A novel double ion-implant (DII) Ti-salicide technology is described. Based on the technology, good performance of uniform Ti-salicide formation, low and narrow distribution of sheet resistances, and low leakage currents are obtained.

Vacuum ultraviolet photons were examined to assess their role in improving the gap fill characteristics of a low dielectric constant material.

The vibrational properties of amorphous [SiO.sub.2] were studied within first-principles density functional theory. The calculated spectrum is in good agreement with neutron data, showing, in particular, a double peak in the high-frequency region. This doublet results from different local modes of the tetrahedral subunits and cannot be ascribed to a longitudinal-optic-transverse-optic (LO-TO) effect. This solves a long-standing controversy about the origin of the doublet in neutron spectra. A LO-TO splitting is recovered only when the long-wavelength limit is probed, as in optical experiments. These findings should be a general feature of tetrahedral [AX.sub.2] amorphous networks., The high-frequency vibrations in amorphous [SiO.sub2] (a-[SiO.sub.2]), corresponding to Si-O stretching modes, are responsible for a double peak that is clearly distinguishable in neutron spectra (1, 2). In the same [...]

A study of charge carrier dynamics, both free and trapped, under nonequilibrium circumstances is presented. The Shockley-Read technique is employed to formulate a set of four differential equations to model thermal charge generation and recombination rates of electrons and holes in both states. They equations model the time-dependence behavior of such charge carriers in the mobility gap of amorphous semiconductors.

Optical coatings are found to be of great importance in aeronautical, aerospace, and astronomical applications. The optical interference thin films used in certain optical systems have been found to be [...]

The application of rapid thermal processing (RTP) in the capacitance control of aluminum (Al) /titanium-tungsten (TiW) /amorphous-silicon (Si) systems is studied. A doping element was implanted in a negative-type Si substrate which caused the formation of an amorphous layer. A TiW layer was then deposited on the substrate surface and the compound was subjected to rapid thermal annealing and frequency tests. Results revealed that the increase in temperature and frequency lowered the capacitance of systems.

A study was conducted to analyze the influence of structure on the electron transfer reactions between anthracene dyes and TiO2 nanoparticles. Controlled hydrolysis was carried in water of titanium(IV) isopropoxide to prepare anatase TiO2 nanoparticles. The Perkin-Elmer Lambda 6UV-vis spectrometer was then utilized to obtain steady-state absorption spectra. Results indicated that the preparation of the particles influenced the time constants for electron transfer for semiconductor particles-bound dye molecules.