In this paper we present luminescence results of nitrogen doped and undoped ZnO layers grown at 100 °C by atomic layer deposition and post grown annealed. A comprehensive analysis of the excitonic peaks as well as the controversial band at ~3.32 eV is presented. Based on temperature dependent luminescence analysis we identified PL peaks originating from donor and acceptor bound excitons D°X and A°X. It has been found that two acceptor-related PL peaks observed between 3.30 and 3.32 eV reveal different temperature behavior. The emission at 3.302 eV has been assigned to donor-acceptor pairs (DAP), whereas the emission at 3.318 eV to free electrons to acceptor transition. Activation of an acceptor as a result of high temperature annealing is reflected in PL spectra as an appreciable increase of the DAP emission. The binding energies of existing donors and acceptors have been also calculated and the possible origin of the donors and acceptors in ZnO and ZnO:N layers grown at low temperature was proposed. Furthermore, the planar cathodoluminescence images discover that acceptor related emission comes from whole grains area.
