G. Conte et al., CPM AND SPECTRAL PHOTOCONDUCTIVITY TECHNIQUES - A CRITICAL ANALYSIS OF THE EXPERIMENTAL RESULTS, Journal of non-crystalline solids, 166, 1993, pp. 419-422
The sub-bandgap absorption in intrinsic a-Si:H films has been measured
by the constant photocurrent method (CPM) in DC and AC conditions, an
d by spectral photoconductivity (SPC) techniques. CPM measurements hav
e been performed at different constant values of the photocurrent in o
rder to investigate its effect on the spectra. Finally, experimental r
esults have been compared with a model of sub-bandgap absorption relyi
ng on the hypothesis that a distribution of charged states is present
above the valence band.