Defects in AlSb: A density functional study

We carry out density functional calculations to study both intrinsic and extrinsic defects in AlSb. We focus on the carrier compensation and trapping properties of these defects, which are important to the radiation detection applications. We show that the Sb antisite (Sb(Al)) is a low-energy defect, with interesting property of light-induced metastability, similar to the As antisite in GaAs. Sb(Al) is effective in compensating holes induced by the residual carbon but is also a deep electron trap that reduces the carrier drifting length. We discuss the possibility of using hydrogenated isovalent N impurity in AlSb and GaAs to pin the Fermi level without causing efficient carrier trapping.