Effect of temperature on the properties of Al:ZnO films deposited by magnetron sputtering with inborn surface texture

Abstract

Al:ZnO (AZO) films were deposited on glass substrate with inborn surface texture by magnetron sputtering at a power density as high as 7 W/cm². The sputtering parameters, such as argon working pressure and substrate temperature were varied from 1.0 to 6.0 Pa and from room temperature to 500 °C, respectively. All the films exhibited perfect (002) orientations with very weak (004) peaks measured by X-ray diffraction. A linear relationship between the growth rate of AZO film and working pressure was found. The AZO film with best electrical properties of all films obtained at room temperature was deposited at working pressure of 2.0 Pa. And the root-mean-square roughness tested by atomic force microscopy was 37.50 nm, which indicated that surface texture was successfully fabricated without further etching process. For higher substrate temperature a decrease in the resistivity was observed due to an increase in the mobility and the carrier concentration. Resistivity low as 9.044 × 10⁻⁴ ohm/cm was obtained at 500 °C and 2.0 Pa, the corresponding mobility and carrier concentration were 20.45 m²/Vs and 3.379 × 10²⁰/cm³, respectively. The grain size and the surface texture size tested by scanning electron microscopy also peaked at 500 °C. All the films showed a relatively high transmittance about 80%.