Positron lifetime, Photoluminescence and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314ps lifetime component, attributed to $V_{ Ga}$ related defect, was identified in the positron lifetime measurement. In the PL measurement, a $778meV$ and a $797meV$ peaks were observed. Isochronal annealing studies were performed and at the temperature of $300^{ o}C$, both the 314ps positron lifetime component and the two PL signals disappeared, which gives a clear and strong evidence for their correlation. However, the hole concentration ($\sim 2\times 10^{ 17}cm^{ -3}$) was observed to be constant throughout the whole annealing temperature range up to $500^{ o}C$. Contradictory to general belief, this implies, at least for samples with annealing temperatures above $300^{ o}C$, the Ga vacancy is not the acceptor responsible for the p-type conduction.
Categories: cond-mat.mtrl-sci