First-principles LDA+U studies of the In-doped ZnO transparent conductive oxide

Abstract

Electronic energy band structure of In-doped ZnO transparent conducting oxide was investigated by density functional calculations using local density approximation+Hubbard U (LDA+U) scheme. By systematically calculating the formation energies and transition energy levels of In atom and In-related complex in ZnO, it has been shown that the substitutional In atom has a low formation energy and introduces a shallow donor level, which is 38 meV below the conduction-band minimum. Substitutional In atoms contribute significantly delocalized s orbitals in the conduction band states, which are expected to increase the mobility of the material. In p-type ZnO, interstitial In atom acts as a donor and has a low formation energy, making it a compensating center in the case of acceptor doping. Under O-rich growth conditions, however, interstitial In is energetically unfavorable. The modulated band structure of ZnO after In doping shows a total energy band gap widening effect due to a pronounced Burstein–Moss shift and a relatively small exchange-correlation-induced band gap narrowing.