Epitaxial growth of CuInSe2 single crystal by halogen transport method

CuInSe₂ single crystals were epitaxially grown on (001) GaP, (001) GaAs, and (110) GaP by the halogen transport method. The orientation relationships in the growth on the (001) and (110) faces were (a) 001]_CuInSe2 001]_sub and 100]_CuInSe2 100]_sub (c-axis orientation growth), and (b) 110]_CuInSe2 110]_sub and 001]_CuInSe2 001]_sub, respectively. On (001) InP, the orientation relationships between the layer and substrate consist of two sets: (c) 100]_CuInSe2 001]_sub and 001]_CuInSe2 010]_sub, and (d) 100]_CuInSe2 001]_sub and 001]_CuInSe2 00]_sub (a-axis orientation growth). The above results, i.e., c-axis growth on (001) GaP and (001) GaAs and a-axis growth on (001) InP, could be explained by a criterion of the minimum lattice mismatch between grown layers and substrates. A series of growth experiments on (001) GaAs indicated that appropriate gas etching of the substrate surface and growth temperature were required for obtaining twin-free single-crystal epitaxial CuInSe₂.