DIFFUSION-CONTROLLED BIMOLECULAR RECOMBINATION OF ELECTRONS AND HOLESIN A-SI-H

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