Acceptors in undoped gallium antimonide

Abstract

Undoped GaSb materials were studied by temperature dependent Hall (TDH) measurements and photoluminescence (PL). The TDH data reveals four acceptor levels (having ionization energies of 7meV, 32meV, 89meV and 123meV) in the as-grown undoped GaSb samples. The 32meV and the 89meV levels were attributed to the GaSb defect and the VGa-related defect. The Ga Sb defect was found to be the important acceptor responsible for the p-type nature of the present undoped GaSb samples because of its abundance and its low ionization energy. This defect was thermally stable after the 500°C annealing. Similar to the non-irradiated samples, the 777meV and the 800meV PL signals were also observed in the electron irradiated undoped GaSb samples. The decrease of the two peaks' intensities with respect to the electron irradiation dosage reveals the introduction of a non-radiative defect during the electron irradiation process, which competes with the transition responsible for the 777meV and the 800meV PL peaks.