Improved defect-pool model for charged defects in amorphous silicon.

Abstract

We have developed an improved defect-pool model for the calculation of the density of dangling-bond states in amorphous silicon. The results of this improved defect-pool model are contrasted with earlier work, from which we have eliminated some errors and approximations. We show that the calculated energy-dependent density of states depends on the specific microscopic reaction involving hydrogen, in contrast to previous conclusions. We calculate the bulk density ofstates, using the best input parameters drawn from experiment, and conclude that the best agreement with experimental results is found for a rather wide defect pool and for a microscopic model where two Si-H bonds break for every weak bond converted into two dangling bonds