QUALITY FACTOR IN A-SI-H NIP AND PIN DIODES

We analyze the forward characteristics of a-Si:H nip and pin diodes. A t low bias, a well-defined exponential region exists, described by a n oninteger quality factor n between 1.2 and 1.7. With increasing temper ature, the quality factor decreases. This behavior can be understood w ith a model based on electron and hole recombination in the i layer, w hich relates the temperature dependence of the quality factor to the d istribution of localized states in the amorphous silicon. The predicti ons of the model are supported by numerical calculations in which the diode device equations are solved for a given distribution of localize d states. The different ideality factors are due to different energy d ependencies of the density of deep states in the i layer.