The degree of interdiffusion at the amorphous semiconductor/bulk Al interface was studied using Auger electron spectroscopy analysis. 300-500 Å thick a-Si:H and a-Ge:H films were deposited onto high-purity Al and 5052 Al alloy substrates and subsequently annealed to various temperatures up to 500 °C for 6 hrs. The high-purity Al is used as a substrate for our small-angle x-ray scattering studies of amorphous silicon-based alloys. For all the films deposited on the pure Al, little or no interdiffusion was noted at or below anneal temperatures of 400°C. This result is contrary to those commonly found for samples produced by evaporating Al onto the previously deposited amorphous semiconductor without breaking the vacuum where interdiffusion has been noted at temperatures at or below 200°C. We suggest interdiffusion in the amorphous semiconductor/bulk Al samples is hindered by the presence of a 150-300 Å Al oxide on the Al. A large amount of interdiffusion and partial crystallization is noted in the a-Ge:H sample after an anneal of 450°C while a temperature between 450 and 500°C is required for interdiffusion and crystallization to occur in the a-Si:H sample. In the case of the a-Ge:H films deposited on the 5052 Al alloy, interdiffusion occurs after 300°C anneals due possibly to the migration of Mg and other components of the alloy into the amorphous semiconductors or structural defects in the alloy which enhance interdiffusion.
Metal contacts to p-type CuInSe 2 and heterojunctions of the form n-(CdZn)Slp-CuInSe 2 have ?een prepared, to investigate the electrical behavior and chemical composition of the resulting Interfaces and to correlate the results with the composition and corresponding electrical properties of CuInSe z . The results indicate that the observed variability of the back contacts and front junctions of different CuInSe 2 samples can be attributed to the variable initial equilibrium concentration of the intrinsic defect states which dominate the crystals. The type and concentration of the dominant defects can be changed by thermal treatments and by interface induced effects due to the junction electric field and the chemical potential gradients. Diffusion into or out of the CulnSe 2 crystals was not detected. More over, no composition or other chemical variation due to the deposition of the sulfide layer was observed.
Absfracf-The dielectric properties of SrTiQj (ST0)NBCO and STO films deposited on LaA103 substrates were evaluated, for potential varactor applications wherein the capacitance is altered via a dc voltage applied across the STO film. The optimal growth temperature for the STO films in the STO/YBCO structures was 800 "C; higher temperatures resulted in interfacial degradation and poor film quality, and lower temperatures resulted in films with lower dielectric constants (E,.) and tunabilities. Interdigital varactors comprised of STO films deposited directly on LaA103 displayed higher tunabilities and significantly lower losses.
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