Growth mode control of ZnO toward nanorod structures or high-quality layered structures by metal-organic vapor phase epitaxy

Abstract In metal-organic vapor phase epitaxy (MOVPE), ZnO growth modes either for nanorod structures or for high-quality flat layers have been successfully controlled by varying the growth conditions. The nanorod structures of ZnO, e.g., 10−50 nm in diameter and 0.5−1 μm in height, were successfully grown on sapphire substrates at lower temperatures (e.g., 500°C). On the other hand, the uniform layers were formed at higher growth temperatures (e.g., 800°C). The best solution, at this stage, for flat epilayers with two-dimensional growth is the homoepitaxial growth on bulk ZnO substrates. The root mean square (RMS) roughness of the surface was minimized as 2 nm and the full-width at half-maximum of low-temperature (9 K) photoluminescence was as narrow as 0.5 meV, indicating the successful formation of high-quality ZnO grown by MOVPE.