分子束外延生长ZnO薄膜及性能研究

Growth and characterization of ZnO thin film prepared by molecular-beam epitaxy on Si(100)

用分子束外延 (MBE)和氧气氛方法 ,并改变束源炉和衬底生长温度 ,在Si(10 0 )衬底上 ,采用Zn作缓冲层以解决ZnO层与衬底间的晶格失配问题 ,生长得到ZnO薄膜。在ZnO Zn Si(10 0 )薄膜样品的X射线衍射 (XRD)谱中 ,观测到ZnO的 (10 0 )、(0 0 2 )、(10 1)、(10 2 )和 (10 3)等衍射峰 ;用原子力显微镜 (AFM)观测ZnO薄膜的表面形貌 ,为直径约 80— 90nm的量子点 ,表明已得到具有纳米结构的ZnO薄膜。用同步辐射EXAFS技术研究了ZnO薄膜的局域结构 。

ZnO is a II-VI compound with a wide direct gap of about 3.37eV at room temperature. It is an important compound for information techniques. The ZnO thin films are deposited on Si (100) substrate by molecular beam epitaxy (MBE) associated with oxygen atmosphere method, under different temperatures of molecular beam source and substrate. The Zn buffer layer is used in order to minimize the effect of mismatch of crystal lattice between Si and ZnO. In the X-ray diffraction spectrum of ZnO/Zn/Si (100), peaks specific to ZnO at (100), (002), (101), (102) and (103) were observed. Images from the atomic force microscope show that the ZnO films are composed of small granules with the size of 80-90nm approximately. The local structure of ZnO films has been studied by the synchrotron radiation EXAFS technique. Some local structural parameters such as bond length, coordination number and disorder degree are obtained for the first shell. We suggest that the disorder of as grown ZnO films be probably due to the existence of hanging bonds on the surface of ZnO nanometer granules.