A comparative analysis of deep level emission in ZnO layers deposited by various methods

This study examined the origin of visible luminescence from ZnO layers deposited on p-Si substrates by various growth methods using temperature dependent photoluminescence measurements. The deep level emissions of ZnO layers are found to be strongly dependent on the growth conditions and growth methods used. For the samples grown by sputtering, the visible emission consisted of violet, green, and orange-red regions, which corresponded to zinc interstitial (Zn_i), oxygen vacancy (V_O ), and oxygen interstitial (O_i) defect levels, respectively. In contrast, the deep level emissions of metal organic chemical vapor deposition grown samples consisted of blue and green emissions and blue and orange-red emissions at low and high oxygen flow rates, respectively. The ZnO nanorods synthesized by thermal evaporation showed a dominant deep level emission at the green region, which is associated with oxygen vacancies (V_O ).