Electroluminescence studies of recombination in hydrogenated amorphous silicon p-i-n devices

We present experimental data on the voltage and temperature $\text{(80<T<300}\text{K}\text{)}$ dependence of electroluminescence and forward bias current in hydrogenated amorphous silicon (a-Si:H) p-i-n structures. Since electrons and holes are injected from opposite sides of the sample, we are able to probe non-geminate radiative and non-radiative recombination processes in the intrinsic layer of actual device structures. We find that the effective generation rate in the electroluminescence experiment is proportional to the square of the applied voltage because the radiative recombination rate is proportional to the double-injection electron density. A simple model of electron recombination rates explains the data. The non-radiative recombination rate was found to be temperature dependent, but the radiative recombination rate is temperature independent.