Photoemission and X-ray absorption studies of the electronic structure of GaN-based diluted magnetic semiconductors

Abstract

We have investigated the electronic structure of Cr- and Mn-doped GaN using photoemission spectroscopy (PES) and X-ray absorption spectroscopy (XAS). Cr and Mn XAS at the L-edge have indicated that the Cr and Mn ions are in the tetrahedral crystal field and that their valences are trivalent and divalent, respectively. Upon Cr and Mn doping into GaN, new states were found to form in the band-gap region of GaN. Resonant photoemission spectroscopy (RPES) has revealed that the main structure of the Cr 3d partial density of states (PDOS) appears within the band gap of GaN while that of the Mn 3d PDOS appears within the valence band of GaN and as a shoulder above the valence-band maximum of GaN, indicating that the character of the doping-induced states is different between Ga 1-x Cr x N and Ga 1-x Mn x N.