DIFFUSION-CONTROLLED BIMOLECULAR RECOMBINATION OF ELECTRONS AND HOLES IN A-SI-H

The fluctuation-dominated and mean-field models for diffusion-controlled bimolecular recombination are compared with picosecond domain transient optical experiments on a-Si:H. Using no fitting parameters, the fluctuation-dominate model gives a good account for the optical decay times as a function of laser intensity. A lower bound for the thermalization radius of a photogenerated electron-hole pair, r(0) > 12 nm, is inferred. a-Si:H is a felicitous material for exhibiting the fluctuation-dominate effects since it combines a modest electron mobility with an unexplained but large thermalization radius. However, the role of the electrostatic potential fluctuations due to the charged electrons and holes is not understood.