A photoluminescence and Hall-effect study of GaSb grown by molecular-beam epitaxy

Unintentionally doped gallium antimonide has been grown by molecular-beam epitaxy on gallium arsenide and gallium antimonide. Substrate temperatures in the range 480 to 620 °C and antimony to gallium flux ratios from 0.65 : 1 to 6.5 : 1 have been investigated. The deposition conditions have been related to growth morphology and to the electrical and optical properties of the epitaxial films. A strong correlation has been found between the quality of the layers and the degree of excess antimony flux; the best material in terms of both optical and electrical properties was obtained with the minimum antimony stable growth at a particular substrate temperature. All the material exhibited residual p-type behavior. The lowest hole concentration achieved was 7.8×1015 cm−3 with a corresponding room-temperature mobility of 950 cm2/V s. The narrowest PL (photoluminescence) features observed were peaks associated with bound exciton transitions with half-widths of 2–3 meV.