Optical Properties of CuInSe2 Single Crystals Grown by the Vertical Bridgman Technique

Abstract
The optical absorption near the fundamental edge of n‐type CuInSe2 single crystals was studied for samples having different impurity concentrations. It is found that with increasing impurity concentration the gap energy decreases whilst the tail absorption below the edge and its characteristic energy increase. It is concluded that band‐gap narrowing due to high ionized impurity concentrations plays an important role in CuInSe2 single crystals.