Annealing effects on the optical and structural properties of Al₂O₃/SiO₂ films as UV antireflection coatings on 4H-SiC substrates

详细信息    查看全文

• 作者：Feng Zhang ; Weifeng Yang ; Aisuo Pang ; Zhengyun Wu ; Hongji Qi ; Jianke Yao ; Zhengxiu Fan ; Ji ; a Shao
• 关键词：Annealing ; Al₂O₃/SiO₂ films ; 4H-SiC ; External quantum efficiency
• 刊名：Applied Surface Science
• 出版年：2008
• 出版时间：15 August 2008
• 年：2008
• 卷：254
• 期：20
• 页码：6410-6415
• 全文大小：832 K

文摘

Al₂O₃/SiO₂ films have been prepared by electron-beam evaporation as ultraviolet (UV) antireflection coatings on 4H-SiC substrates and annealed at different temperatures. The films were characterized by reflection spectra, ellipsometer system, atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. As the annealing temperature increased, the minimum reflectance of the films moved to the shorter wavelength for the variation of refractive indices and the reduction of film thicknesses. The surface grains appeared to get larger in size and the root mean square (RMS) roughness of the annealed films increased with the annealing temperature but was less than that of the as-deposited. The Al₂O₃/SiO₂ films maintained amorphous in microstructure with the increase of the temperature. Meanwhile, the transition and diffusion in film component were found in XPS measurement. These results provided the important references for Al₂O₃/SiO₂ films annealed at reasonable temperatures and prepared as fine antireflection coatings on 4H-SiC-based UV optoelectronic devices.