Optical and Electrical Characterization of CuGaS2 Grown by Vapor Phase Epitaxy

Investigations were made on band-edge-region photoluminescence and the electric resistivity of CuGaS2 epitaxial films on GaAs and GaP substrates, which were prepared by vapor phase epitaxy using metal chlorides and H2S gas. The similar temperature dependence was observed on the resistivity and the intensity of 2.40 eV emission, giving nearly the same activation energy of about 0.05 eV. This value suggests the existence of an acceptor shallower than the acceptor of effective mass approximation. A proposed candidate of this shallow acceptor is an interstitial chlorine atom coming from source materials.