Revert stable p-type ZnO with LimN complex co-doping from the first-principles study

Although lithium-nitrogen dual acceptor (LimN) co-doping has been experimentally applied successfully for the realization of p-type conductibility in bulk ZnO, the observed p-type conductivity usually suffers instability issues. In this contribution, we have employed first-principles method within the framework of density functional theory to explore the driving mechanism of p-type conductivity in LimN-doped ZnO with an emphasis on the lithium concentration (i.e., m = 1-4). Through examining the formation energy of different doping configurations and corresponding band structures, we find that Li2N complex doping (i.e., with a Li interstitial bound to a Li-N dual-acceptor co-doping center) is responsible for the p-type conductivity. However, such a complex is energetically meta-stable. Excess Li-interstitial in bulk ZnO sample could easily cross the energy barrier (similar to 0.39 eV) and bind to the Li2N doping center, and form a stable but neutral Li3N cluster, causing the disappearance of p-type conductivity. This therefore explains the experimental instability phenomenon observed in the (Li, N)-doped ZnO. This work can be interesting and useful for designing electronic and optoelectronic devices based on p-type ZnO.