Ion beam channeling studies of scandium incorporation into ScAlN

Recently, the incorporation of scandium (Sc) into wide bandgap semiconductors has generated great interest due to the possibility of transforming pyroelectric materials into promising piezoelectric and ferroelectrics. Indeed, the incorporation of Sc into AlN and GaN facilitates a piezoelectric response if the wurtzite (WZ) polytype is maintained. ScN typically crystallizes in the rocksalt (RS) polytype although metastable WZ polytypes have been reported. Here, we investigate the mechanisms for Sc incorporation into MBE-grown ScxAl1-xN layers using channeling Rutherford backscattering spectrometry (RBS/c). Using 1.5 MeV He2+, we measured [0001] channeling, random, and angular yield scans of ScxAl1-xN layers grown on AlN-on-Al2O3 templates. For the AlN-on-Al2O3 templates, the [0001] minimum yield is 0.6, and the in-plane angular yield scans exhibit similar half-depths, suggesting the presence of mixed RS-WZ polytypes within the Sc0.3Al0.7N layers. To determine the site occupancy of Sc, RBS/c studies along the [1100] and [11-20] directions are in progress.