Sensitivity of the spectral response of a-Si:H Schottky barriers to the density of states profile: a computer simulation

Schottky-barrier solar cell structures are convenient devices for studying the basic properties of the intrinsic a-Si:H used in solar cells. A first-principles computer analysis of the spectral response (SR) of such structures is used to examine the sensitivity of SR to the midgap density of states, the donor tail characteristic energy, and the acceptor tail characteristic energy in a-Si:H materials. It is shown that the SR, either with or without a red bias light is uniquely affected by these three density-of-states parameters. The uniqueness arises because certain groupings of states are efficient trapping centers, efficient recombination centers, or some combination of both. The uniqueness of these simulations shows that computer analysis of SR sensitivities can be used to monitor density-of-states profiles and thereby assess the quality of a-Si:H materials