Angular-dependent channeling Rutherford backscattering spectroscopy (c-RBS) has been used to quantify the fraction of Cr atoms on substitutional, interstitial, and random sites in epitaxial Ga1-x Crx N films grown by reactive molecular-beam epitaxy. The morphology of these films and correlation with their magnetic properties has been investigated. Films grown at temperatures below ~750 °C have up to 90% of Cr occupying substitutional sites. Post-growth annealing at 825 °C results in a systematic drop in the fraction of substitutional Cr as well as a fall off in the ferromagnetic signal. The roles of nonsubstitutional Cr in transferring charge from the Cr t2 band and segregation of substitutional Cr in the loss of magnetism are discussed. Overall, these results provide strong microscopic evidence that Cr-doped III-N systems are dilute magnetic semiconductors.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)