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

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 mum in height, were successfully grown on sapphire substrates at lower temperatures (e.g., 500degreesC). On the other hand, the uniform layers were formed at higher growth temperatures (e.g.. 800degreesC). 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. (C) 2002 Elsevier Science B.V. All rights reserved.