Thermal evolution and migration behavior of ion-implanted nitrogen in ZnO:In-N films

摘要

Thermal evolution and migration behavior of nitrogen (N) dopants in indium (In) doped ZnO films implanted with high-dose N ions (ZnO:In-N) were investigated by means of experiment and first-principles calculations. The results demonstrate that N-dopants have poor thermal stability, which has a significant impact on N local chemical states. In particular, two different temperature regions can clearly be distinguished in the annealing process. At low-temperature region, the interaction of substitutional nitrogen (N-o) acceptor and interstitial nitrogen (N-i) starts to occur, which leads to a decrease in N-o acceptor and the formation of additional molecular nitrogen at oxygen site [(N-2)(o)]. In contrast, at high-temperature region, annealing favors energetically the generation of abundant oxygen vacancies near the surface and simultaneously induces the serious out-diffusion of N-dopants. Combined with the calculated migration barriers, oxygen vacancies are deemed to assist the out-diffusion of N-dopants via a vacancy mechanism. This work provides insights into the formation and evolution of different N-related defects and their interaction with intrinsic defects.