Abstract
We have studied the influence of intrinsic defects, cation vacancies (VCu, VIn) and anti-site defects (InCu, CuIn), on the bandstructure of nonstoichiometric CuInS2 based upon the ab-initio electronic band-structure calculations using the augmented spherical wave (ASW) method. We have found that an energy shift of the center of gravity of S 3p band is a key parameter for controlling change in the type of conductivity. In p-type crystals (VCu, CuIn, and VIn), we have clarified an increase in the strength of the interaction between Cu 3d states and S 3p states caused by a weight shift of the S 3p band towards higher energies in contrast to that in n-type (InCu).