ELECTRONIC AND OPTICAL-PROPERTIES OF N-TYPE A-SI-H

Films of n-type hydrogenated amorphous silicon (a-Si:H) have been grow n using a mixture of silane and tertiarybutylphosphine (TBP: C4H11P) w hich is a less toxic source than phosphine. A plasma enhanced chemical vapor deposition system was used to grow the films at a deposition te mperature of 250 degrees C. The ratio of TBP to silane was varied from 10(-4)% to 3% by volume. The films were characterized by measuring ph otoluminescence, temperature dependence of dark dc conductivity, below -gap absorption coefficient and dark electron spin resonance. It is fo und that, up to similar to 0.5% concentration of TBP, the experimental -results are in accordance with the auto-compensation doping model. Ho wever, significant discrepancies are observed at higher impurity conce ntrations.