Journal of Materials Research

Articles

Effect of film thickness on the structural and electrical properties of Ga-doped ZnO thin films prepared on glass and Al2O3 (0001) substrates by RF magnetron sputtering method

Seung Wook Shin, S.M. Pawara1, Tae-Won Kima2, Jong-Ha Moon and Jin Hyeok Kima3 c1

a1 Department of Materials Science and Engineering, Chonnam National University Puk-Gu, Gwangju 500-757, South Korea

a2 Honam Technology Service Division National Center for Nanoprocess and Equipments, Korea Institute of Industrial Technology, Gwangju 500-480, South Korea

a3 Department of Materials Science and Engineering, Chonnam National University Puk-Gu, Gwangju 500-757, South Korea

Abstract

Thin films of Ga-doped ZnO (GZO) were prepared on glass and Al2O3 (0001) substrates by using RF magnetron sputtering at a substrate temperature of 350 °C, RF power of 175 W, and working pressure of 6 mTorr. The effect of film thickness and substrate type on the structural and electrical properties of the thin films was investigated. X-ray diffraction study showed that GZO thin films on glass substrates were grown as a polycrystalline hexagonal wurtzite phase with a c-axis preferred, out-of-plane orientation and random in-plane orientation. However, GZO thin films on Al2O3 (0001) substrates were epitaxially grown with an orientation relationship of S0884291400031575_inline1. The structural images from scanning electron microscopy and atomic force microscopy showed that the GZO thin films on glass substrates had a rougher surface morphology than those on Al2O3 (0001) substrates. The electrical resistivity of 1000 nm-thick GZO thin films grown on glass and Al2O3 (0001) substrates was 3.04 × 10−4 Ωcm and 1.50 × 10−4 Ωcm, respectively. It was also found that the electrical resistivity difference between the films on the two substrates decreased from 9.48 × 10−4 Ωcm to 1.45 × 10−4 Ωcm with increasing the film thickness from 100 nm to 1000 nm.

(Received July 22 2008)

(Accepted October 16 2008)

Key Words:

  • Electrical properties;
  • Physical vapor deposition (PVD);
  • Thin film

Correspondence:

c1 Address all correspondence to this author. e-mail: jinhyeok@chonnam.ac.kr

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