Influence of oxygen partial pressure on transparency and conductivity of RF sputtered Al-doped ZnO thin films

Transparent conductive Al-doped ZnO thin films were prepared on glass substrates by radio frequency RF. diode sputtering with ArqO2gas at an Al2O3-mixed ZnO ceramic target. The samples, with constant thickness of 0.5 mm, were prepared under various O2 partial pressure ratios in the range of 0% to 3%, and then annealed at 4008C for 4 h in a vacuum furnace. Their electrical, optical, and X-ray diffraction properties were evaluated. The resistivity of transparent films was in the range of 5=10y3 to 1=10y2 VPcm, the carrier concentration was 2=1020 cmy3, Hall mobility was 3–6 cm2rV s, and the property of infrared wavelength cutoff was confirmed. Introducing O2 gas prevented the films from yellow coloration caused by lack of oxygen atoms, and improved the durability with respect to cracking and peeling caused by residual stress. Atomic force microscopy and X-ray diffraction measurements showed that the lateral grain size was 100–150 nm and vertical grain size was about 12 nm. q2000 Elsevier Science B.V. All rights reserved