Photoelectron Spectroscopy and Optical Properties of Al-Doped ZnO Films Prepared by Sputtering with Radio Frequency Power Applied to Al Target - Archive ouverte HAL Access content directly
Journal Articles Japanese Journal of Applied Physics Year : 2013

Photoelectron Spectroscopy and Optical Properties of Al-Doped ZnO Films Prepared by Sputtering with Radio Frequency Power Applied to Al Target

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Abstract

Al-doped ZnO (AZO) films were prepared on a glass substrate using a magnetron sputtering system. The metallic aluminum and ZnO targets were bombarded by radio frequency power source. The Al-dopant concentration of the films, analyzed by energy-dispersive spectroscopy, increased with increasing RF power. The electrical resistivity of the films, measured by four-point probe, revealed a decrease from 3.43 ×10-2 to 3.29 ×10-3 Ω cm with increasing Al-content from 0.85 to 4.34 at. %. The crystal structure analyzed by grazing incidence X-ray diffraction indicated that all of the films prepared by sputtering with RF power preferred a stronger texture on (002) orientation than those with DC power applied to Al target. The optical transmittance, measured by UV–visible, indicated an average transmittance higher than 82% for all the films in visible region, and increased with Al-content; however, it reversed at 4.34 at. %. The band gap of the films increased from 3.39 to 3.58 eV with increasing RF power. Ultraviolet photoelectron spectroscopy (UPS) analysis revealed that a characteristic peak at approximately 5–7 eV was found in the AZO films due to the O 2p valence electrons. Meanwhile, the work functions of the undoped ZnO film and various AZO films were measured by UPS decreased from 4.9 to 4.5 eV with increasing Al-content. The chemical composition of the films was analyzed by X-ray photoelectron spectroscopy with Gaussian-resolved fitting. According to XPS analysis of O 1s for the films, we inferred that the decrease in electrical resistivity of the film with increasing Al-dopant concentration was predominated by the concentration of oxygen vacancies.
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Dates and versions

hal-02441280 , version 1 (15-01-2020)

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Chun-An Tseng, Jing-Chie Lin, Wei-Heng Weng, Chen-Chun Lin. Photoelectron Spectroscopy and Optical Properties of Al-Doped ZnO Films Prepared by Sputtering with Radio Frequency Power Applied to Al Target. Japanese Journal of Applied Physics, 2013, 52 (2R), pp.025801. ⟨10.7567/JJAP.52.025801⟩. ⟨hal-02441280⟩

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