Low temperature growth of c-axis oriented AlN films on γ-LiAlO2 by radio frequency magnetron sputtering

Aluminum nitride (AlN) films were prepared on γ-LiAlO2 substrates by radio frequency (rf) magnetron sputtering. The influence of substrate temperature (Ts) and nitrogen (N2) concentration on film growth was investigated. The X-ray diffraction (XRD) results reveal that highly c-axis oriented AlN films can be obtained in the temperature range from room temperature (RT) to 300 °C. A smoother surface and a crystalline quality decrease with increasing N2 concentration have been observed by XRD and atomic force microscopy (AFM) for the films deposited at lower substrate temperature. On the contrary, the degradation of the surface smoothness and the higher crystalline quality can be observed for the films deposited at a higher substrate temperature with N2-rich ambient. The growth mechanism which leads to different crystalline quality of the films is discussed.