LIGHT-INDUCED CHANGES IN a-Si : H ANALYSED BY FIELD EFFECT MEASUREMENTS

Abstract
Amorphous Si : H films deposited by glow discharge technique are analysed by field effect in both annealed and light-changed states. The spatial distribution of potential through the sample and the state density convolution with the derivative of the Fermi function are extracted, by a new method, directly from the experimental data. It is found that, in the light-changed state, the higher conductivity activation energy associates to a density of states near the Fermi level which is lower than in the annealed state. The effect of light exposure appeares to be similar to weakly "p" type doping the a-Si, without significantly changing the midgap state density.