Fe-doped AlN films were deposited on n-type Si (100) and quartz substrates by a reactive direct current magnetron
sputtering system in an atmosphere of Ar and N2 at room temperature. The target was a mixture of Al and Fe with a
weight ratio 10:1. In order to study the effect of N2 flow rate (FN2) on the structure and optical properties of Fe-doped AlN film, FN2 changed from 0 to 50 sccm. The microstructure, surface morphology, and optical properties of the films were investigated by X-ray diffraction, atomic force microscopy, and spectrophotometer, respectively. Experimental results show that the films are amorphous when FN2 is less than 3 sccm. AlN (100) diffraction peak can be seen in all the samples as FN2 is larger than 6 sccm. Fe3N (202) and AlN (103) peaks are found in the samples at FN2 of 20 and 30 sccm. AlN (110) peak appears at 40 sccm sample. Surface roughness and grain diameter of the samples on both Si and quartz substrates sharply decrease as FN2 increases from 0 to 10 sccm. When FN2 is larger than 10 sccm, the
change in surface roughness and grain diameter is small. Optical transmittance of the film on quartz substrates increases with increasing FN2. The maximum transmittance is higher than 90% when FN2 is higher than 20 sccm. When FN2 increases from 10 to40 sccm, the optical energy gap increases from 5.483 to 5.601 eV.