Analysis of the edge emission of highly conductive CuGaTe2

Low temperature photoluminescence of CuGaTe2 was studied using number of different samples. Totally 11 photoluminescence bands were detected in the edge emission region. It is shown that at least 6 bands have peak positions at higher energy than the lowest optical bandgap of CuGaTe2. These bands were explained by using a model of resonant acceptor states (Fano-type resonances) in the valence band of CuGaTe2. Thus, the electron from the conduction band or from the donor level recombines with holes from acceptor levels related to the different valence bands. The energetic distance between these valence bands is found to be 84 meV