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Discusses a study which applied a real time spectroellipsometry data analysis procedure to characterize depth profiles in the optical gap for semiconductor alloy thin films prepared by plasma enhanced chemical vapor deposition. Theoretical background; Description of the experimental setup; Findings.

Presents information on a study which investigated the stress in diamond films prepared by microwave plasma chemical vapor deposition as a function of methane concentration and deposition temperature. Calculation of thermal stress; Dependence of the total and intrinsic stress on methane concentration; Stress dependence on deposition temperature; Origin of tensile intrinsic stress.

Reports on the application of real time spectroscopic ellipsometry to characterize the nucleation of diamond on c-silicon by tungsten filament-assisted chemical vapor deposition (CVD). Stages of diamond growth by filament-assisted CVD; Preparation of the diamond; Information on the structural model and parameters deduced in a linear regression analysis of the final spectra.

A combination of photolithography written with a near-field scanning optical microscope, gallium electrodeposition, and arsine annealing was used to produce regular arrays of submicron GaAs dots on a silicon substrate. Electrodeposition on a patterned Si surface produced an array of roughly hemispherical Ga dots. Annealing in arsine converted the gallium to GoAs, and caused the dots to develop faceted features. Transmission electron microscope measurements showed that the GaAs dots were polycrystalline, but had only a few grains. The dots did not have a preferred orientation relative to the substrate. Metalorganic chemical vapor deposition growth occurred selectively on these dots, forming regular arrays of GaAs disks up to 20 μm in diameter. The GaAs disks exhibited characteristic GaAs low-temperature photoluminescence. This method has application for precisely positioning semiconductor dots or tailoring the grain size of polycrystalline films. [ABSTRACT FROM AUTHOR]

In studies of hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells fabricated by rf plasma-enhanced chemical vapor deposition (PECVD), we have found that the maximum open circuit voltage (V[sub oc]) is obtained by incorporating p-type doped Si:H layers that are protocrystalline in nature. Specifically, these optimum p layers are prepared by PECVD in the a-Si:H growth regime using the maximum hydrogen-to-silane flow ratio possible without crossing the thickness-dependent transition into the mixed-phase (amorphous+microcrystalline) growth regime for the ∼200 Å p-layer thickness. The strong dependence of the p-layer phase and solar cell V[sub oc] on the underlying i-layer phase also confirms the protocrystalline nature of the optimum Si:H p layer. [ABSTRACT FROM AUTHOR]

We report the first observations of resonant tunneling in electronic transport perpendicular to two AlAs layers separated by a GaAs quantum well in GaAs/AlAs heterostructures grown by metalorganic chemical vapor deposition. Resonant tunneling can be observed as inflections in the 1-V curves at room temperature. These inflections become more pronounced as the temperature is reduced, until negative differential resistance regions become visible for temperatures below 260 K. At low temperatures, the I-V curves not only reveal two large negative resistance regions corresponding to the first energy level in the GaAs quantum well but also a structure which shows evidence of resonant tunneling through the second and possibly the third energy states in the well. Second derivative (d²1/dV²) measurements confirm the existence of the resonances seen in the I-V curves. [ABSTRACT FROM AUTHOR]

Real time spectroscopic ellipsometry has been applied to characterize the substrate temperature (T) dependence of the deposition rates for nanocrystalline diamond thin films prepared by microwave plasma-enhanced chemical vapor deposition on seeded Si substrates. With the real time capability, it is possible to determine the rates at which the diamond mass thickness (i.e., volume per area) increases during the early nucleation and bulk film growth regimes. The increases in the nucleating and bulk diamond growth rates with T for 400