Wurtzite [11-20]-oriented AlFeN films prepared by RF sputtering

We report herein on a high degree of wurtzite [11-20] orientation in AlN films heavily doped with Fe (AlFeN). The AlFeN films were deposited by RF sputtering on SiO2 glass and sapphire (0001) substrates. X-ray diffraction measurements revealed the Fe concentration dependence of the preferred orientation of these films. At a high Fe concentration (10–26.1%), the films had a [11-20] orientation, whereas films with less than 5% of Fe had a [0001] orientation. This tendency was evident on sapphire (0001) substrate as well as on the SiO2 glass substrate. The highest degree of [11-20] orientation was achieved for 19.4% of Fe. Transmission electron microscopy observations of the [11-20]-oriented AlFeN films (Fe: 19.4%) showed that randomly oriented nuclei form near the interface with the substrate, and subsequently, columnar grains selectively grow with a [11-20] orientation. These results suggest that AlFeN (11-20) films may be potentially applicable as a buffer layer to grow non-polar AlN on various substrates.