Effects of Native Point Defects on Indium Antimonide

Radiation detection requires a probe that is sensitive to the involved photon energies. For infrared detection this implies the need for materials with narrow bandgaps, such as InSb. However, defects induced during material synthesis or radiation exposure may introduce new electronic states and recombination pathways that can reduce detector reliability. Our Density-Functional-Theory (DFT) results show that defect formation energies are consistent with previously published computations to within 0.2 eV and reproduce defect formation energy trends. However, standard DFT computations predict erroneously metallic behavior for InSb, a finding that can be corrected with Hubbard-U+V extensions to standard DFT. Among the point defects (Sb_In, In_Sb, V_Sb, and V_In) we investigated, we find that only Sb_In and V_Sb show evidence for electronic states in the bandgap. Combined with the DFT defect formation energies, we predict that Sb_In is the dominant defect under Sb-rich conditions, mimicking experimental synthesis protocols. Therefore, IR detector reliability requires that Sb_In defect abundance must be reduced as much as possible to ensure IR detector reliability. *SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.