Raman scattering and magnetizations studies of (Al, Cr)-codoped 4H-SiC

In this study, the insertion of both Al and Cr atoms into SiC matrix has been experimentally evidenced by X-ray diffraction, Raman scattering, elements analysis and magnetic measurements. Structure analysis showed that (Al, Cr)-codoped SiC has a single-phase 4H-crystal structure and no trace of any other impurity phases were detected. Raman scattering showed that several new features appeared in (Al, Cr)-codoped 4H-SiC: (1) the vanishing of the folded longitudinal-optical phonons modes-plasmon coupling (FLOPC) modes with x=(q/qB)=0; (2) an obvious absorbing peak was found in Si1−x−yAlxCryC with y=0.0203 at%; (3) folded transverse-optical (FTO) mode shifts to high frequency and linewidths [full widths at half maximum (FWHM)] decrease with increase in Cr content. Magnetic properties characterizations showed that weak ferromagnetism order is established. With increase in Cr content, the magnetization decreased. No clear influence of Al doping on the magnetic properties of codoped 4H-SiC is evidenced while the magnetic origin should be ascribed to be induced by Cr. It is speculated that doping Cr elements at Si sites destroy the effective coupling of the spins induced by Al doping. The major role of Al is to stabilize the codoped crystal structure as 4H-single-phase.

► We found that codoping Al and Cr elements can also be realized in SiC lattice.
► No traces of any other impurities phase were detected by various characterizations means.
► In other words, codoping strategy of using (Al, TM) elements is useful to approach natural magnetic properties of TM-doped SiC.