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Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films

Min-Chul Jun, Sang-Uk Park and Jung-Hyuk Koh*

Author Affiliations

Department of Electronic Materials Engineering, Kwangwoon University, Seoul, 139-701, South Korea

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Nanoscale Research Letters 2012, 7:639  doi:10.1186/1556-276X-7-639

Published: 22 November 2012

Abstract

We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol–gel spin-coating process. As a starting material, AlCl3⋅6H2O, Ga(NO3)2, and Zn(CH3COO)2⋅2H2O were used. A lowest sheet resistance of 3.3 × 103 Ω/□ was obtained for the GZO thin film doped with 1.5 mol% of Ga after post-annealing at 650°C for 60 min in air. All the films showed more than 85% transparency in the visible region. We have studied the structural and microstructural properties as a function of Al and Ga concentrations through X-ray diffraction and scanning electron microscopy analysis. In addition, the optical bandgap and photoluminescence were estimated.

Keywords:
AZO; GZO; Transparent conducting oxide; Thin films; Spin-coating