Defect Properties of Nitrogen in ZnO

ZnO has applications in optoelectronics and is used as a transparent semiconductor. However, p-type electrical
doping of has proved difficult to achieve, with group-V impurities substituting for O being suggested as a solution. Using
first-principles local density functional theory, we extensively studied the properties of N doping. In agreement with others,
we find that NZn is the dominant donor rendering ZnO n-type, and a complex of NZn with Zn vacancies is an acceptor,
although not particularly shallow. NO has deep donor and acceptor levels through the formation of N –O bonds in the
positive charge state. We also studied interstitial O and N, which showed that they readily form complexes with
substitutional N and can enhance n-type over p-type conductivity in N-doped ZnO.