Dependence of photoconductivity on the dark Fermi level position in amorphous silicon alloys

We present results of a new model to describe the dependence of the room-temperature steady-state photoconductivity in amorphous silicon alloys upon the position of the dark Fermi level. This dependence is a consequence of both a change in the recombination path and dopant-created gap states. We also demonstrate the relationship between the power dependence of photoconductivity and dark Fermi level position and show that as a result of space charge neutrality, this dependence can be related to a characteristic energy slope of the density of states only in the absence of injected charge or dopants. Moreover, in agreement with recent experimental data, we show that our model predicts a power dependence of less than 0.5 for high-intensity illumination on n-type amorphous silicon.