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Optical and Wetting Properties of CuAlO2 Films Prepared by Radio Frequency Magnetron Sputtering

Authors

  • Junlei Li,

    1. School of Physics and Material Science, Anhui University, Hefei, China
    2. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
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  • Xian Wang,

    1. School of Physics and Material Science, Anhui University, Hefei, China
    2. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
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  • Shiwei Shi,

    1. School of Physics and Material Science, Anhui University, Hefei, China
    2. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
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  • Xueping Song,

    1. School of Physics and Material Science, Anhui University, Hefei, China
    2. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
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  • Jianguo Lv,

    1. School of Physics and Material Science, Anhui University, Hefei, China
    2. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
    3. Department of Physics and Electronic Engineering, Hefei Normal University, Hefei, China
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  • Jingbiao Cui,

    1. Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, Arkansas
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  • Zhaoqi Sun

    Corresponding author
    1. Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei, China
    • School of Physics and Material Science, Anhui University, Hefei, China
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  • This work was financially supported by National Natural Science Foundation of China (Nos. 50872001, 51072001, 51102072), National Science Research Foundation for Scholars Return from Overseas, Ministry of Education, China, Youth Science Research Foundation of Anhui University (No. 2009QN008A) and “211 Project” of Anhui University.

Author to whom correspondence should be addressed. e-mail: szq@ahu.edu.cn

Abstract

The CuAlO2 films were prepared on glass and quartz substrates by radio frequency magnetron sputtering with a sintered target composed of Al(OH)3 and Cu2O powders. X-ray diffraction analyses reveal that the as-deposited films are amorphous structure and the as-annealed films are predominated by the CuAlO2 phase along with the Al2O3 phase. Scanning electron microscope (SEM) measurements indicate that grains grow up and surface becomes rougher as a result of increasing temperature. The optical studies show that annealing leads to the reduction of the average transmittance of the films from 60% to 40% for the visible range and the decrease of the fitted refractive index from 2.0 to 1.5. Direct band gaps confirmed by the transmittance and reflectance measurements are estimated to be 3.86 and 3.50 eV for as-deposited and as-annealed films, respectively. As increasing exposure time, water contact angles of the as-deposited films exposed under ultraviolet light source 365 nm or 254 nm decrease from 96.3° and 96.4° to 87.5° and 87.2°, respectively. The variation of contact angle can be attributed to the hydrophobic organic stains on the surface, surface roughness, the formation of Cu2+, and band gap variation of CuAlO2 film. The as-annealed film becomes hydrophilic and its water contact angle is 31.1°. The wetting property of CuAlO2 films is very important for the wide spread application of this material.

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