Characterization of Al(Cr)N and Ga(Cr)N dilute magnetic semiconductors

Thin Al(Cr)N and Ga(Cr)N films with a range of Cr concentrations were grown on 6H-SiC substrates by reactive molecular beam epitaxy at temperatures in the range 700-825 deg. C. Optimized Al(Cr)N and Ga(Cr)N films were found to be ferromagnetic with Curie temperatures above 900 K. Structural characterization by electron microscopy and electron diffraction revealed epilayers with columnar morphology and excellent crystallinity. Further examination ruled out any known secondary ferromagnetic impurities in Al(Cr)N, whereas very small amounts (∼0.2%) of antiferromagnetic CrN were detected in the Ga(Cr)N films. Distribution of Cr in the films was analyzed using energy-filtered imaging