Photoluminescence of high-quality GaSb grown from Ga- and Sb-rich solutions by liquid-phase epitaxy

Abstract

The temperature dependence of photoluminescence from the high-quality unintentionally doped GaSb layers grown by liquid-phase epitaxy has been studied. The epitaxial layers grown at temperatures above 590 °C, from the Ga- or Sb-rich solutions, reproducibly have a low-carrier concentration of 6–8×1015 cm−3 and exhibit p-type conduction. But it gives n type as grown from the Ga-rich solution at 360 °C. For the samples grown from the Ga-rich solutions, the 16 K photoluminescence spectrum is dominated by the partially resolved lines related to the transitions of excitons bound to donors and neutral acceptors. The acceptor-related band (777.8 meV) which is always presented in the GaSb material due to the native lattice defects has been much reduced as compared to the exciton-related lines. Especially for the n-type samples grown at low temperatures (360 °C), the ratio of the emission intensity from the exciton-related lines to that from the acceptor-related band is 10. For the samples grown from the Sb-rich solutions, the 16 K photoluminescence spectrum is also dominated by a bound exciton-related line with a full width at half maximum of 4.2 meV. In addition, the free-exciton transition with a full width at half maximum of 0.4 meV is also observed. As the temperature is increased, the intensity of the lines associated with the bound excitonic transitions for all the GaSb samples rapidly quenches off and the free-electron-to-free-hole transition becomes dominant. The temperature dependent band gap in GaSb layers determined from the photoluminescence peak energy varies as 0.813–[1.08×10−4 T2/(T−10.3)] eV.