An empirical density of states and joint density of states analysis of hydrogenated amorphous silicon: a review

A number of empirical models for the valence band and conduction band hydrogenated amorphous silicon density of states functions are presented. Then, a relationship between these density of states functions and the imaginary part of the dielectric function is developed. The joint density of states function, which plays a key role in determining the spectral dependence of the imaginary part of the dielectric function, and is directly related to the valence band and conduction band density of states functions, is defined in the process. Joint density of states results, corresponding to a specific empirical density of states model, are then presented. Finally, the modeling results for the imaginary part of the dielectric function are contrasted with those of experiment and satisfactory agreement is found. (C) 2004 Kluwer Academic Publishers.