The ability of positrons to probe local defect structures has been utilized to compare differences in residual damage structures in self-irradiated silicon for differing tempera¬tures of the implanted substrate. Sb-doped < 100 > silicon was self irradiated with a 600 keV beam to fluences ranging from 3 x 1014 to 1 X 1016 ions/cm2 at liquid nitrogen, room and slightly elevated (61° C) temperatures. A defect was identified near the end-of-range of the implanted ions whose concentration diminished at higher implant temperatures, but was only weakly dependent on total fluence. Comparison between Sb- and B-doped Si suggests that the defect is impurity based.

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.

Contactless transient photoconductivity measurements in a- Si:H/c-Si heterojunctions are presented. The experimental data are decomposed in the contribution of excess electrons in a-Si:H, the contribution of excess carriers in c-Si and the contribution of excess carriers injected from a-Si:H into c-Si. A value for the electron drift mobility of in a-Si:H of 1cm2 V-1 s-1 is determined. At low excitation densities a high injection efficiency is observed, which is quenched by bias illumination.

We present experimental results showing that Cr/p+/V amorphous silicon memory structures at room temperature exhibit step-like current-voltage characteristics associated with discrete, non-random resistance values. The resistance values observed are ∼26kΩ/i where i is an integer or half integer. The low bias current-voltage characteristics prior to the first step suggest that conduction in this regime is governed by tunneling across a region having very small dimensions, of the order of ∼5-7 Å, and having a diameter ∼30-50 Å.