Polarity control of GaN grown on ZnO (0001¯) surfaces

We have investigated the growth temperature dependence of the structural properties of GaN deposited on O-polarity ZnO (0001¯) using pulsed laser deposition. We have found that atomically abrupt GaN∕ZnO heterointerfaces are obtained at growth temperatures reduced to below 500°C. We have also found that GaN grown at room temperature (RT) exhibits a Ga polarity while that grown at 700°C exhibits a N polarity. However, it is possible to grow Ga-polarity GaN at 700°C by the introduction of a RT buffer layer. First principles calculations well explain how Ga-polarity GaN may be grown on atomically flat O-polarity ZnO surfaces at low temperatures.