The nature of photoconductivity decay spectral dependence in a-Si:H

Abstract

Photoconductivity decay rate from constant steady state level after switching off the light is found to be strongly dependent on h v . At liquid nitrogen temperatures this dependence is exponential for all h v <1.8 eV in a-Si:H of any quality. At room temperatures in poor quality a-Si:H the border of this dependence shifts to 1.1 eV while in electronic quality a-Si:H non-monotonous spectral dependence of decay is observed with the longest decay time at 1.1 eV. We present some experimental evidences that this effect may be due to different recombination mechanisms prevailing at h v <1.1 ev and h v >1.1 eV and speculate what these mechanisms might be.