Band Alignment of the CuGaS₂ Chalcopyrite Interfaces Studied by First-Principles Calculations

The valence and conduction band offsets for both polar and nonpolar CuGaS₂/CuAlSe₂ and CuGaS₂/ZnSe interfaces were studied here by the state-of-the-art first-principles calculations. Using the hybrid functional calculations, we show that the CuGaS₂/CuAlSe₂ and CuGaS₂/ZnSe heterostructures in all interfaces form type II band alignment. The difference of valence and conduction band offsets is mainly due to lattice mismatch, generating stress in the interface and affecting the electronic properties of each material; meanwhile, the polarity configuration does not play an important role in these values. From the local density of states and the charge density, we can determine how the nature of the band alignments changes when the semiconductor conforms to each interface. This allows us to localize the electrons and holes at different sites of the interface.