Preferential growth of ZnO thin films by the atomic layer deposition technique

Abstract

Preferred orientation of ZnO thin films deposited by the atomic layer deposition (ALD) technique couldbe manipulated by deposition temperature. In this work, diethyl zinc (DEZn) and deionized water(H2O) were used as a zinc source and oxygen source, respectively. The results demonstratedthat (10.0) dominant ZnO thin films were grown in the temperature range of155–220 °C.The c-axis crystal growth of these films was greatly suppressed. Adhesion of anions (such as fragmentsof an ethyl group) on the (00.2) polar surface of the ZnO thin film was believed to be responsiblefor this suppression. In contrast, (00.2) dominant ZnO thin films were obtained between 220 and300 °C. The preferred orientations of (10.0) and (00.2) of the ZnO thin films were examined byXRD texture analysis. The texture analysis results agreed well with the alignmentsof ZnO nanowires (NWs) which were grown from these ZnO thin films. In thiscase, the nanosized crystals of ZnO thin films acted as seeds for the growth ofZnO nanowires (NWs) by chemical vapor deposition (CVD) process. Thehighly (00.2) textured ZnO thin films deposited at high temperatures, such as280 °C, containedpolycrystals with the c axis perpendicular to the substrate surface and provided a good template for the growth ofvertically aligned ZnO NWs.