OPTICAL AND ELECTRICAL CHARACTERIZATION OF THICK GASB BUFFER LAYERS GROWN ON 2-IN GAAS WAFERS

We have investigated the growth of thick, highly uniform GaSb buffer layers on 2 in GaAs substrates. We have found that ramping the temperature under an arsine flux optimizes the switching sequence between GaAs and GaSb. In this case, the large (about 8%) lattice mismatch which separates the Ga-As and Ga-Sb bond lengths is abruptly relaxed, and good quality GaSb can be homogeneously deposited. On such samples, the photoluminescence signal ranks as well (or even better) as that obtained for comparative homoepitaxial material; also, the electrical properties are among the best ever reported for GaSb grown by metal-organic chemical vapor deposition on GaAs.