Substitution mechanism of Ga for Zn site depending on deposition temperature for transparent conducting oxides

• Published in: Current applied physics Vol. 12; no. 6; pp. 1586 - 1590
• Main Authors: Lee, Deuk-Hee, Kim, Kyoungwon, Chun, Yoon Soo, Kim, Sangsig, Lee, Sang Yeol
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2012; 한국물리학회
• Subjects: Austenitic stainless steels; Carrier density; Deposition; Doping; electrical resistance; Ga-doped ZnO; Gallium; glass; oxygen; temperature; Thin films; transmittance; Transparent conducting oxide; X-ray diffraction; X-ray photoelectron spectroscopy; X-rays; Zinc; Zinc oxide; 물리학; Zinc oxide; Ga-doped ZnO; X-ray photoelectron spectroscopy; Transparent conducting oxide
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2012.05.009

High quality transparent conductive gallium-doped zinc oxide (GZO) thin films were deposited on glass substrates using rf-magnetron sputtering system at the temperature ranging from room temperature (RT) to 500 °C. The temperature-dependence of Ga doping effect on the structural, optical and electrical properties in ZnO has been investigated. For the GZO thin films deposited at over 200 °C, (103) orientation was strongly observed by X-ray diffraction analysis, which is attributed to the substitution of Ga elements into Zn site. X-ray photoelectron spectroscopy measurements have confirmed that oxygen vacancies were generated at the temperature higher than 300 °C. This might be due to the effective substitution of Ga3+ for Zn site at higher temperature. It was also found that the optical band gap increases with deposition temperature. The optical transmittance of GZO thin films was above 87% in the visible region. The GZO thin films grown at 500 °C showed a low electrical resistivity of 4.50 × 10−4 Ω cm, a carrier concentration of 6.38 × 1020 cm−3 and a carrier mobility of 21.69 cm2/V. [Display omitted] ► High quality transparent conductive gallium-doped zinc oxide (GZO) thin films were deposited on quartz glass substrates using rf-magnetron sputtering system in the deposition temperature range of room temperature (RT) to 500 °C. ► The temperature-depedence of Ga doping effect on the structural, optical and electrical properties in ZnO has been investigated. ► X-ray photoelectron spectroscopy measurements on GZO thin films was confirmed that the oxygen vacancy was generated because Ga3+ was substituted for Zn site more actively at the deposition temperature of higher than 300 °C. ► The optical transmittance of GZO thin films was represented above 85% in the visible region. The GZO thin films formed at a deposition temperature of 500 °C showed a low electrical resistivity of 4.50 × 10−4 Ω cm, a carrier concentration of 6.38 × 1020 cm−3 and a carrier mobility of 21.69 cm2/V.