The contribution of Cr(III)-doping on the modulation of magnetic and luminescence properties of GaN nanowires

Abstract

An external incorporation of magnetic ions into the parent compounds is often used to tune their semiconducting behavior. For example, doping of a small amount of transition metal ion in a semiconductor can lead to the formation of dilute magnetic semiconductors (DMSs) that can exhibit some novel properties related to spin interactions. Here, we report on Cr(III)-doped GaN nanowires (NWs), prepared by a thermal evaporation method. X-ray diffraction analysis indicates the single crystalline nature of as-synthesized NWs. Each NW is composed of hexagonal-facet with sharp conical shaped tip investigated by a scanning electron microscope (SEM). The appearance of 2LO mode in micro-Raman spectra indicates a strong electron-phonon coupling with the A 1 (LO) mode induced by Cr(III) ion. The occurrence of ferromagnetic domains as observed in GaN plays an important role in spin ordering which comes from mixed spin-spin, exciton-spin, and spin-carrier interaction. These findings provide a new path to realize new spin-polarized photonic devices . • Well-shaped Cr-doped GaN nanowires grown by CVD. • A large redshift effect of A 1 (LO) as compared with bulk GaN. • Ferromagnetic coupling between transition metal ions and GaN lattice. • Formation of exciton magnetic polaron (EMP) due to high exciton binding energy. • Strong interactions resulting in exciton-spin or phonon interactions.