Dependence of Argon Gas Pressure on the Structure and Photoelectric of Ga-Doped ZnO Thin Films Deposited by DC Magnetron Sputtering

Ga-doped zinc oxide (GZO) thin films had been deposited by DC magnetron sputtering method at high argon (Ar) gas pressure and 250°C temperature on glass substrates. The Ar sputtering pressure was varied between 12.1 and 12.9 Pa. The results indicated the GZO thin films had a hexagonal wurtzite structure and highly C-axis preferred out-of-plane orientation. As the Ar gas pressure increased,the GZO films (002) diffraction peak intensity gradually decreased,indicating the C-axis preferred out-of-plane orientation became worse. Meanwhile the crystallite size were decreased,indicating the crystal surface became better. The sheet resistance and resistivity both increased with the Ar gas pressure increased which was due to a decreased of both mobility and carrier concentration, and the lowest value of sheet resistance and resistivity was 25Ω/Υ, 1.0519 × 10-3 Ω·cm, respectively. The average transmittance of the GZO thin films in the visible spectra was over 80%,and the optical band gap was smaller than intrinsic Zinc oxide (ZnO).