Influence of nitrogen flow ratio on the optical property of AlN deposited by DC magnetron sputtering on Si (100) substrate

Aluminum nitride (AlN) films were deposited on Si (100) substrate at room temperature in different N-2 flow ratios (N-2/(N-2 + Ar)) by direct current (DC) magnetron sputtering. AlN films were prepared with the N2 flow ratios from 20 to 50%. The intensity of X-ray diffraction peak on (002) plane enhanced with the increase of N-2 flow ratio. When the flow ratio of N-2 was 50%, the AlN film tended to be the most preferred orientation of (002) plane with the value of full width half maximum being 0.34 degrees. Optical property was studied by ellipsometer and the refractive index of the samples was between 1.92 and 2.05. According to the Fourier transform infrared spectroscopy, the density of Al-N bonds went up gradually and the tensile stress had a rising trend with the increasing N-2 flow ratio. In short, this work is helpful for the growth of AlN buffer layer deposited on Si (100) substrate.