Gallium vacancy and the residual acceptor in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence

Positron lifetime, photoluminescence (PL), and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314 ps positron lifetime component was attributed to Ga vacancy (V_Ga) related defect. Isochronal annealing studies showed at 300°C annealing, the 314 ps positron lifetime component and the two observed PL signals (777 and 797 meV) disappeared, which gave clear and strong evidence for their correlation. However, the hole concentration (∼2×10¹⁷cm^-3) was observed to be independent of the annealing temperature. Although the residual acceptor is generally related to the V_Ga defect, at least for cases with annealing temperatures above 300°C, V_Ga is not the acceptor responsible for the p-type conduction.