ZnO薄膜的分子束外延生长及性能

MBE Preparation and Characterization of ZnO Thin Film

利用分子束外延 (MBE)和氧等离子体源辅助MBE方法分别在Si(1 0 0 )、GaAs(1 0 0 )和蓝宝石Al2 O3(0 0 0 1 )衬底上用Zn、ZnS或以一定Zn O化学计量比作缓冲层 ,改变衬底生长温度和氧压 ,并在氧气氛下 ,进行原位退火处理 ,得到ZnO薄膜。依据X射线衍射 (XRD)图 ,表明样品的结晶性能尚好 ,且呈c轴择优取向 ;实验结果表明在不同衬底上生长的ZnO薄膜 ,由于晶格失配度不同 ,其衍射峰也有区别。用原子力显微镜(AFM)观测薄膜的表面形貌 ,为晶粒尺寸约几十纳米的ZnO纳米晶 ,且ZnO晶粒呈六边形柱状垂直于衬底的表面。采用掠入射X射线反射率法测膜厚。在 36 0nm激发下 ,样品的发光光谱是峰值为 4 1 0 ,5 1 0nm的双峰谱 。

By using the molecular beam epitaxy (MBE) and plasma assisted MBE with oxygen atmosphere, the ZnO thin films were deposited on Si(100),GaAs(100) and Al 2O 3 (0001) substrates with Zn,ZnS,or Zn O buffers respectively,under different temperatures of beam source and of substrate. The buffer layer is necessary for preparation of ZnO thin film, in order to minimize the effect of mismatch of crystal lattice between substrates and ZnO. In the X ray diffraction spectrum, we can observe peaks specific to ZnO at (100), (002), (101), (102), and (103). There are some shifts of diffraction peaks for ZnO thin film at different substrates. The atomic force microscope images (AFM) show that the ZnO films are composed of small granules with nano size. The thickness of film was found about several nanometers, by using the grazing incidance X ray reflectivity method. Under the excitation of 360 nm, the photoluminescence of ZnO films is a broad spectrum with peaks at 410 and 510 nm. We suggest that the luminescence is due to deep levels related to the oxygen defects at the surface.