Selfconsistent Analysis of Mobility-Lifetime Products and Subgap Absorption on Different PECVD A-SI:H Films

Abstract

ABSTRACTThe photoconductivity and subband gap absorption measurements over a wide range of generation rate(G) have been carried out ondiluted and undiluted a-Si:H films. It is found that in these high quality films there are significant differences in the functional dependence of mobility-lifetime(μτ) products on G. In additionto the different values of subgap absorption(a) there are also distinct differences in the dependence of a on photon energy (E) as well as G. It is difficult to selfconsistently analyze the results on theundiluted film with the previously used three gaussian distribution, particularly at high generation rates. Selfconsistent analysis isobtained when the (+/0) transitions of negative charged defects andthe (0/-) transitions of positive charged defects are introducedrespectively closer to the valence and conduction bands. This new gapstate distribution is a better representation for the defectpool model and potential fluctuation model.