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Plasma-enhanced vapor deposition was used to deposit amorphous silicon oxynitride films.

Plasma-enhanced chemical vapor deposition methods were used for carbon-doped SiO2:F films deposited by changing the CH4 flow rate.

A study was conducted to analyze structural changes of polycrystalline silicon films support different deposition temperature. The role of deposition temperature and surface structure of substrates on the growth mechanism and structural characteristics of the films were examined. Results indicated that crystalline at a lower deposition temperature correlated with the surface morphology of the substrates.

The structural and bonding characteristics of 200-nm-thick polycrystalline Si films deposited by altering the deposition temperature through plasma-enhanced chemical vapor deposition of monosilane-hydrogen mixtures were studied. Findings showed that except for deposition temperature at 150 and 650 deg C, crystallization of the films was observed. Two infrared absorption bands around 850 and 1000/cm and an increase in the density of Si dangling bonds were observed in deposition temperatures above 500 deg C.

Research was conducted to examine the structure, optical absorption and photoluminescence (PL) properties of SiO(sub x) films which were subjected to thermal annealing at 750-1100 degrees C. Results revealed that threshold energies in optical absorption of the Si nanocrystallites were higher than that for bulk Si. Findings also showed that the PL peak energy of the annealed films changes to higher energy with decreasing crystallite size. It is concluded from the results that a localized state contributes to the PL mechanism.

Undoped amorphous-Si (a-Si) films are deposited as a function of deposition temperature on fused quartz substrates by low pressure chemical vapor deposition using 100% disilane. The texture of these poly a-Si films is significantly influenced by the deposition temperature of the initial films which serve as the substrates. The films grown below a temperature of 530 degrees Celsius exhibit a dominant (100) texture and beyond this temperature, a (111) texture. A decrease in deposition temperature results in a reduction of the nucleation rate.

A plasma-enhanced chemical vapor deposition method facilitates the deposition of undoped polycrystalline Si (poly-Si) as a function of rf power and deposition temperature using disilane. A shift in the surface-diffusion coefficient of (SiH)n adsorbates and ion bombardment effects result in a change in texture. The x-ray relative intensity and crystallinity of the poly-Si films decreases with decrease in film thickness. Increase in rf power or thickness favor formation of a low-angle grain boundary rather than an amorphous-like structure.

SiH4-NH3-H2 mixtures facilitated plasma-enhanced chemical vapor deposition of amorphous SiNx:H (a-SiNx:H) films at 300 degrees centigrade. The amorphous films revealed low intrinsic stress, high break-down strength and low buffered HF (BHF) etch rate, when RH and rf power values increased. Such films were used as passivation layers and gate insulators in thin-film transistors. The relaxation of intrinsic stress is due Si-NH-Si bond formation.

The correlation between the stress and bonding characteristics of amorphous hydrogenated SiNx thin films deposited on single crystal Si was investigated using a modified random bonding model. The results showed that intrinsic stress was responsible for the measured tensile stress infilms with an N content higher than 1.0. The incorporated NH bonds induced the intrinsic stress to relax.

The effect of phosphorous and nitrogen doping of polycrystalline SiC films prepared by plasma-enhanced chemical vapor deposition was investigated. The results showed that phosphorous and nitrogen doping of the SiC films enhanced the crystallinity of the material. However, high doping conditions resulted in a deterioration in the crystallinity. In addition, resistivity and dangling-bond density decreased as the crystallinity was enhanced.

X-ray diffraction and x-ray photoelectron spectroscopy were used to investigate the bonding characteristics of glow-discharge polycrystalline and amorphous Si-C films. The results showed that crystallization accompanied some degree of segregation of carbon atoms in grain boundaries. Bonds were observed in high carbon films, and this resulted in a compressive strain.

Undoped polycrystalline films were deposited from a SiH4-H2 mixture by a plasma-enhanced chemical vapor deposition method. Changingpreparation conditions influence the preferential orientation to a random, (100) or (110) crystal axis. Electron spin resonance and the dependence of dark conductivity on measurement temperature have been examined to determine how the structure of the grain boundary depends on the preferential orientationand affects the electrical properties.

Refractive-index dispersion for the TlInGaAs quaternary alloys, grown on (100) InP substrates by gas-source molecular-beam epitaxy, has been measured at temperatures from 290 to 350 K in the photon-energy range of 1.2-2.0 eV by using spectroscopic ellipsometry. The results also agrees with recently reported small temperature-variation of the lasing-wavelength for the TlInGaAs/InP laser diodes.

We have studied the behavior of ferritin molecules using a high-speed atomic force microscope (high-speed AFM), which uses a miniaturized cantilever and scan stage to reduce the mechanical response time of the cantilever and to prevent the onset of resonant motion at high scan speeds. Using this instrument, we were able to achieve scan rates of up to 1 frame per second for pure fluids. A conventional AFM can visualize the ferritin molecule-substrate interaction directly at the single-molecule level. The conventional AFM can dynamically visualize the process of the ferritin molecule interacting with the substrate; however, it cannot dynamically visualize the adsorption of ferritin molecules on the substrate, which occurs in a fraction of a second, because of its very low scan speed. In this study, we used a novel high-speed AFM to dynamically visualize the behavior of the ferritin molecule-substrate reaction at the single-ferritin-molecule level by real time. [ABSTRACT FROM AUTHOR]

It was formerly confirmed by experiment that hypervelocity impacts on aluminum plates cause microwave emission. In this study, we have carried out experiments in order to clarify the mechanism of the emission. The microwave is detected by heterodyne detection scheme at 22 and 2 GHz with an intermediate frequency bandwidth of 500 and 120 MHz, respectively. A nylon projectile is accelerated using a light-gas gun to impact a target. First, aluminum plates with ten different thicknesses ranging from 1 to 40 mm were used as a target, and microwave signals were detected. The experimental results are statistically analyzed assuming a Gaussian distribution of the emitted power. The standard deviation of pulse voltage is calculated to show the existence of two kinds of signals: sharp pulse and thermal noise. It is shown that the emitted energy and the dispersion have a relation with the extent of the target destruction. Next, nylon projectiles are impacted on different metals such as aluminum, iron, and copper. These results suggest that microcracks are essential to microwave emission. Finally, in order to clarify the mechanism of charging and discharging across the microcracks, the experimental results are compared with this model for the following factors: (1) the thermally excited electrons and the emitted power, and (2) the bond dissociation energy of target material and emitted power. The analytical results suggest that electrons are excited thermally and by transition from a crystalline state to an atomic state. [ABSTRACT FROM AUTHOR]

The local crystal structure and local electronic structure of low-temperature-grown Ga1-xCrxN (0.011-xCrxN is around x=0.04 for the layers grown at 600 °C. Above the solubility limit, the onset of the formation of the CrN-like local structure occurs. The effective valency of Cr in GaCrN was found to be Cr(III) from the x-ray absorption near-edge structure (XANES). The results of XANES also revealed a drastic change in the local electronic structure of Ga1-xCrxN with x between 0.04 and 0.047. This is most likely due to the transformation of the Cr–N atomic configuration from that of substitutionally incorporated GaCrN into a CrN-like local structure. The presence of p-d hybridization between d orbitals of Cr and p orbitals of N has been confirmed in its preedge structure, which could play a role in its ferromagnetism. [ABSTRACT FROM AUTHOR]

Luminescence properties of the transition-metal chromium-doped gallium nitride (GaCrN) epitaxial layers on sapphire substrates have been extensively studied by varying the doping level, excitation intensity, and temperature of study. Photoluminescence spectra of the doped films were found to be dominated by an excitonic peak around 3.25–3.29 eV in accordance with the doping level, due to the transition of neutral-donor bound excitions of GaCrN cubic modification. It is attributed that Cr, which is an acceptor in GaN matrix, acts as a surfactant and modifies the growth kinetics to induce phase modification from wurtzite to zinc blende of GaN. Moreover, Cr doping induced a blue band centered around 2.9 eV, which is a donor-acceptor pair, and also two bound excitonic lines at 3.36 and 3.31 eV at some locations of the sample: the expected origin of these is due to the transitions of excitons bound at the stacking faults which are formed due to the co-existence of hexagon and cubic modifications of GaN. The Raman-scattering spectra have also showed both the wurtzite GaN characteristic phonon signal E2 (high) at 568 cm-1 and cubic GaN (TO)-phonon signal at 553 cm-1, and confirmed the existence of polymorphism in the doped films. High-resolution transmission electron microscopy and selected area electron-diffraction patterns give a visual comparison and authenticate the doping-induced polymorphism in the GaCrN films. [ABSTRACT FROM AUTHOR]

Amorphous SiO2 (a-SiO2) layers were prepared using a thermal oxidation method. The SiO2 layers were nitrided at a temperature Tn between 450 and 650 °C utilizing a plasma generation system, in which the layers before the nitridation were simultaneously grown on two different n-type crystalline Si substrates, one having a high resistivity for electron-spin resonance (ESR) and Fourier transform infrared absorption measurements and another having a low resistivity for current–voltage (I–V) measurement. We found the breakdown strength, estimated based on the I–V characteristics, increased with increasing Tn until 550 °C, but the annealing at a further high Tn caused also a decrease in the breakdown strength. We found a strong correlation between the changes in the I–V characteristics and those in the bonding properties, and this correlation was also discussed in connection with the change in the ESR properties for the a-SiOxNy layers. Furthermore, incorporation of N atoms into SiO2 layers at Tn=550 °C was suggested to improve the structural properties and the electrical properties. [ABSTRACT FROM AUTHOR]

Microwave emission due to hypervelocity impacts on metallic plates has been found. The targets used in the experiment are aluminum plates with various thicknesses. The projectile, a nylon cylinder with metal screw of 0.21 gm, was accelerated up to the velocity of 4 km/s; a heterodyne receiver detected the microwave at 22 GHz. The emission is a random sequence of pulses with several nanosecond width, which lasts more than 10 μs. The phenomenon seems to be dependent on the extent of target destruction through the formation of impact craters or penetration. If so, we could use the characteristics of the phenomena to better understand the mechanical destruction process. We propose several models for the cause of this microwave generation and study them on the basis of timing relation of observed events. [ABSTRACT FROM AUTHOR]

The correlation between the Hall coefficient ([R.sub.H]) and electrical resistivity ([rhp]) is analyzed by measuring two transport coefficients in fcc dihydride phase yttrium (Y[H.sub.x]). The studies have shown a linear relationship between [R.sub.H] and [rho] at room temperature after dihydrogenation of yttrium.

The structural properties of a-SiO(sub x)N(sub y) layers with different compositions prepared using a plasma nitridation technique for thermally oxidized SiO2 layers by means of current-voltage (I-V), electron-spin resonance (ESR) and Fourier transform infrared spectroscopy (FTIR) measurements is discussed.

The fabrication of self-formed quantum dot (QD) structures is discussed. The precise control of emission wavelength of the quantum dots (QD) is described.

Focuses on a study which investigated the bonding properties and annealing effects for glow-discharge amorphous silicon nitride. Methodology; Mechanisms that can be considered as possible origins for chemical shifts; Result of the incorporation of hydrogen in amorphous silicon nitride.

Presents a study that investigated the nitridation process and the annealing effects of silicon-nitride layers using x-ray photoelectron spectroscopy and Auger electron spectroscopy. Methodology; Estimation of the nitrogen concentration in the silicon-nitride regions; Examination of the kinetic energy of silicon.

Presents a study that investigated the effects of the incorporation of phosphorus and nitrogen impurities on the electrical and structural properties of polysilicon carbide thin films. Methodology; Examination of the resistivity and spin density of the samples; Analysis of the crystallinity of the samples.

Presents information on a study which discussed changes of the structural and electrical properties brought about by an in situ plasma supply during growth of undoped and boron doped low-pressure chemical vapor deposition poly-silicon film and plasma-enhanced chemical vapor deposition films. Structural property; Effects of plasma supply on improvement of the surface roughness; Electrical property.

Presents information on a study which analyzed the effects brought about by the addition of nitrogen on the bonding properties as a function of the degree of crystallization for boron-doped microcrystalline into amorphous silicon nitride[subx]:hydrogen films. Investigation of the degree of crystallization by means of x-ray diffraction; Vibrational-absorption profiles; Electrical and optical properties.

Provides information on an experiment investigating the structure, optical absorption and photoluminescence (PL) properties of SiOx films subjected to thermal annealing at 750-1100...C. Methodology used to conduct the experiment; Information on Optical absorption; Results of the experiment.

High lateral density quantum dot (QD) structures are self-formed by growing GaAs/InAs short-period superlattices (SLs) on InP (411)A substrates by gas source molecular beam epitaxy. Multilayer QD structures sandwiched with InP barrier layers showed a strong photoluminescence emission. The 1.3–1.6 μm wavelength emission was easily obtained and precisely controlled by regulating the SL period as well as the number of InAs monolayers (layer thickness). This wavelength control can be understood by considering the carrier confinement along the growth direction as well as the effective well depth change. [ABSTRACT FROM AUTHOR]

Presents a study of the crystal structure and the bonding configurations of Si[sub1-x]C[subx] films prepared by plasma-enhanced chemical vapor deposition. Description of cubic silicon carbide; X-ray diffraction pattern on the films; Classification of films according to the composition.