Local Structure, Magnetic And Transport Properties Of Co-doped SiC-based Diluted Magnetic Semiconductors

Diluted magnetic semiconductors have become a new hotspot in the spintronicsfor the properties of electron charge and spin. At present, the research about the SiC ofthe third generation of wide bandgap semiconductors is still infancy at home andaboard. So the research object of choosing SiC is of theoretical significance andpotential application prospects. In this paper, the films of Mn/Co, Mn/Al, and Co/Nco-doped SiC were prepared by RF magnetron sputtering techniques. The localstructure, magnetic and transport properties of these films have been investigatedsystemically by EDS, SEM, XRD, XPS, XAFS, SQUID, HALL, and R-T et al.. Theresults are following:The as-deposited films of Mn/Co, Mn/Al and Co/N co-doped SiC display apattern of typical amorphous structure. After being annealed at800℃, the films formthe structure of3C-SiC, and the Co2Si secondary phase compounds also emerge infilms. After being annealed at1200℃, the crystal structure of3C-SiC improve andmore Co2Si compounds appear in films. For the Mn/Al co-doped SiC films, thedoping Al can improve the films forming3C-SiC structure, and after being annealedat1200℃, Al9Si compounds also appear in films.The doping Mn and Co atoms exist in the form of Mn2+and Co2+in Mn/Coco-doped SiC films, respectively. The doping Mn atoms exist in the form of Mn2+inMn/Al co-doped SiC films. While some Al atoms form Al clusters, and the othersenter into the SiC lattice, existing in form of Al3+in the films. The doping Co and Natoms exist in the form of Co2+and N3-in Co/N co-doped SiC films, respectively.The doping Mn and Co atoms substitute for C sites of3C-SiC lattice in the filmsand the doped Co atoms formed Co2Si compounds in1200oC annealed films. Thedoping Mn atoms substitute for C sites of3C-SiC lattice in Mn/Al co-doped SiC films,but the Al substitute for C sites of3C-SiC lattice only in800oC annealed films. Thedoping N atoms substitute for C sites of3C-SiC lattice in Co/N co-doped SiC films.Some Co atoms substitute for the C sites of3C-SiC lattice and the other formed Co-Sicompounds in annealed films. There are no metal clusters in Mn/Co, Mn/Al and Co/Nco-doped SiC films. Compared to the type of p，p (Co, Mn) co-doped SiC, the type ofp，n (Co, Mn) co-doped SiC can easily restrain the secondary phase forming.The films of Mn/Co, Mn/Al and Co/N co-doped SiC show the typical semiconductor behavior. In low temperature range, the carriers transport mechanismof the films accords with the Mott variation model, namely lnρ keeps lineardependence with (T)-1/4. The carriers are localized in the films. In3C-SiC films,compared to the p-type of Co doped SiC, The p-type of Al doped SiC has moreeffective carriers modulation. However, the N elements in co-dopd films show then-type of carriers modulation.The films of Mn/Co, Mn/Al and Co/N co-doped SiC display the roomferromagnetism. The saturation magnetization of films increases with the annealedtemperature and doping content of Mn and N. The origin of FM can be explained byBMP model and the FM observed at room-temperature is intrinsic. Compared to thesame concentration of transition metal single doped SiC, the introduction of Co, Aland N in films improve the ferromagnetism of films.