Ab-Initio Studies of Radiation Damage in GaSb

Radiation damage is a known challenge for the continued operation of infrared sensors. The origin of this challenge is the occurrence of new electronic states that often reside in the bandgap of the defect-free material, providing additional pathways for electron relaxation. Unfortunately, due to the narrow bandgap, exploration of the new electronic features and their effects on device performance is challenging for experiment and theory. For example, standard Density-Functional-Theory (DFT)/ab initio methods erroneously predict that GaSb is metallic. In the present study, we are using a modified DFT method, Hubbard-U+V, and correctly find that GaSb is a semiconductor with a bandgap of Eg≈0.76 eV; close to the extrapolated experimental T=0K bandgap, Eg≈0.81 eV. Our preliminary results show that Sb_Ga and Ga_Sb antisite defects and vacancies have distinct electronic, optical, and magnetic signatures. Our presentation will compare and contrast these features of point defects in GaSb and discuss their potential for interrupting continued IR detector operation.