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]CuInSc2 parallel-to [001]sub and [100]CuInSe2 parallel-to [100]sub (c-axis orientation growth), and (b) [110]CuInSe2 parallel-to [110]sub and [001]CuInSe2 parallel-to [001]sub, respectively. On (001) InP, the orientation relationships between the layer and substrate consist of two sets: (c) [100]CuInSe2 parallel-to [001]sub and [001]CuInSe2 parallel-to [010]sub, and (d) [100]CuInSe2 parallel-to [001]sub and [001]CuInSe2 parallel-to [100BAR]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.