Vacancies in CuInSe2: new insights from hybrid-functional calculations

Abstract

We calculate the energetics of vacancies in CuInSe2 using a hybrid functional (HSE06, HSE standing for Heyd, Scuseria and Ernzerhof), which gives a better description of the band gap compared to (semi)local exchange–correlation functionals. We show that, contrary to present beliefs, copper and indium vacancies induce no defect levels within the band gap and therefore cannot account for any experimentally observed levels. The selenium vacancy is responsible for only one level, namely, a deep acceptor level ϵ(0/2−). We find strong preference for VCu and VSe over VIn under practically all chemical conditions.