Microstructure control of ZnO thin films prepared by single source chemical vapor deposition

The columnar structure of ZnO thin films with respect to the incident angle prepared by single source chemical vapor deposition (SS CVD) on Si (1 0 0) substrate was examined. Growth was performed using a volatile precursor Zn4O(CO2NEt2)(6). It was found by scanning electron microscopy that the columnar structure depended on the incident angle between substrates and vapor sources. However, the X-ray diffraction spectra indicate that the [0 0 2] crystallographic orientations of ZnO thin films were perpendicular to the substrate planes, irrespective of the incident angle, and were not aligned with the columnar growth orientations as may be expected. The c-axis orientation of SS CVD ZnO thin films is easily aligned with the (0 0 2) plane surface of the substrate because of its surface anisotropy and the optimal growth is on the face with the highest density and the lowest surface-free energy. (C) 2003 Elsevier B.V. All rights reserved.