Pung Swee-Yong, Choy Kwang-Leong, Hou Xianghui, Shan Chongxin
School of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
Nanotechnology. 2008 Oct 29;19(43):435609. doi: 10.1088/0957-4484/19/43/435609. Epub 2008 Sep 22.
Preferred orientation of ZnO thin films deposited by the atomic layer deposition (ALD) technique could be manipulated by deposition temperature. In this work, diethyl zinc (DEZn) and deionized water (H(2)O) were used as a zinc source and oxygen source, respectively. The results demonstrated that (10.0) dominant ZnO thin films were grown in the temperature range of 155-220 °C. The c-axis crystal growth of these films was greatly suppressed. Adhesion of anions (such as fragments of an ethyl group) on the (00.2) polar surface of the ZnO thin film was believed to be responsible for this suppression. In contrast, (00.2) dominant ZnO thin films were obtained between 220 and 300 °C. The preferred orientations of (10.0) and (00.2) of the ZnO thin films were examined by XRD texture analysis. The texture analysis results agreed well with the alignments of ZnO nanowires (NWs) which were grown from these ZnO thin films. In this case, the nanosized crystals of ZnO thin films acted as seeds for the growth of ZnO nanowires (NWs) by chemical vapor deposition (CVD) process. The highly (00.2) textured ZnO thin films deposited at high temperatures, such as 280 °C, contained polycrystals with the c axis perpendicular to the substrate surface and provided a good template for the growth of vertically aligned ZnO NWs.
通过原子层沉积（ALD）技术沉积的ZnO薄膜的择优取向可通过沉积温度来控制。在本工作中，分别使用二乙基锌（DEZn）和去离子水（H₂O）作为锌源和氧源。结果表明，在155 - 220 °C的温度范围内生长出以（10.0）为主的ZnO薄膜。这些薄膜的c轴晶体生长受到极大抑制。据信，阴离子（如乙基片段）在ZnO薄膜的（00.2）极性表面上的吸附是造成这种抑制的原因。相比之下，在220至300 °C之间获得了以（00.2）为主的ZnO薄膜。通过XRD织构分析研究了ZnO薄膜的（10.0）和（00.2）择优取向。织构分析结果与从这些ZnO薄膜生长出的ZnO纳米线（NWs）的取向非常吻合。在这种情况下，ZnO薄膜的纳米晶体通过化学气相沉积（CVD）过程作为ZnO纳米线（NWs）生长的种子。在高温（如280 °C）下沉积的高度（00.2）织构的ZnO薄膜包含c轴垂直于衬底表面的多晶体，并为垂直排列的ZnO NWs的生长提供了良好的模板。
