Controlled Growth of Zn-Polar ZnO Films on Al-Terminated α-Al2O3(0001) Surface by Using Wurtzite MgO Buffer

• 来源期刊: 中国物理快报(英文版)
• 年，卷（期）: 2007,（8）
• 页码范围: 2408-2411
• 页数: 4页
• 语种: 英文

摘要

The controlled growth of Zn-polar ZnO films on Al-terminated α-Al2O3 (0001) substrates is investigated by the radio-frequency plasma-assisted molecular beam epitaxy method. Prior to the growth, α-Al2O3 (0001) surface is modified by an ultrathin MgO layer, which serves as a uniform template for epitaxy of Zn-polar ZnO films. The microstructures of ZnO/MgO/Al2O3 interface are investigated by in-situ reflection high-energy electron diffraction observations and ex-situ high-resolution transmission electron microscopy characterization. It is found that under Mg-rich condition, the achievement of the wurtzite MgO ultrathin layer plays a key role in the subsequent growth of Zn-polar ZnO. An interfacial atomic model is proposed to explain the mechanism of polarity selection of both MgO and ZnO films.