Research on Defects and Transport in Amorphous-Silicon-Based Semiconductors, Annual Subcontract Report, 20 February 1992 - 19 February 1993

Abstract

This report describes Phase 2 progress in two areas: (1) electron drift and conduction band tails in a-Si{sub 1{minus}x}Ge{sub x}:H and a-Si{sub 1{minus}x}C{sub x}:H alloys, and (2) optical bias effects on electron trapping and emission in a-Si:H. The authors completed a comprehensive study of electron drift in a-Si{sub 1{minus}x}Ge{sub x}:H alloys, including correlations of the drift parameters with {open_quotes}blue{close_quotes} fill factor measurements and open-circuit voltages in solar cells. They began a study of electron and hole drift in a-Si{sub 1{minus}x}C{sub x}:H, but, at present, they have only confirmed that C alloying degrades the electron drift mobility in a-Si{sub 1{minus}x}C{sub x}:H. They completed a study of optical bias effects on transient photocharge measurements in a-Si:H, which clarified that optical bias effects found in earlier photocurrent transient measurements occur because deep trapping is suppressed by optical bias.