EVIDENCE FOR HOLE TRAPS AT THE AMORPHOUS SILICON AMORPHOUS SILICON-GERMANIUM HETEROSTRUCTURE INTERFACE/

Voltage-pulse stimulated capacitance transient measurements on a serie s a-Si:H/a-Si, Ge:H devices disclose a large density of hole traps at or very close to the heterojunction interface. The transient signal ma gnitude is independent of temperature or applied bias, ruling out char ge polarization effects or a defect creation process caused by the fil ling pulse. While the areal density of such hole traps is considerable (within a factor of 2 of 10(11) cm(-2) for all samples) these traps d o not appear to behave as recombination centers. Also, the treatment o f the a-Si:H/a-Si,Ge:H interface during growth can significantly alter the concentration of these traps. (C) 1997 American Institute of Phys ics.