Realization of nonpolar a-plane ZnO films on r-plane sapphire substrates using a simple single-source chemical vapor deposition

Nonpolar (11 (2) over bar0) ZnO thin films (a-plane ZnO) have been grown on (1 (1) over bar 02) sapphire substrates (r-plane sapphire) by a simple atmospheric pressure single-source chemical vapor deposition (SSCVD) approach. The crystallinity, surface morphology and optical property of the films were investigated using high-resolution X-ray diffraction (HRXRD), scanning electron microscope (SEM) and transmission spectrum, respectively. XRD results revealed that the ZnO films were grown on the substrates epitaxially along (11 (2) over bar0) orientation, and the epitaxial relationship between the ZnO films and the substrates was determined to be (11 (2) over bar0)ZnO parallel to(1 (1) over bar 02) Al2O3, and [(1) over bar 101]ZnO parallel to[02 (2) over bar1] Al2O3. The SEM image exhibited that the a-plane ZnO films showed a high density of well-aligned ZnO sheets with rectangular structure. The transmission spectrum showed that the ZnO films were highly transparent in the visible region. (C) 2010 Elsevier B.V. All rights reserved.