Investigation Of Structure, Magnetic And Transport Properties Of Doped SiC-based Diluted Magnetic Semiconductors

Over the last few years, dilute magnetic semiconductors(DMSs) have been put on huge interests due to their promising applications in spintronic devices. It has been predicted room temperature(RT) ferromagnetism might be obtained in wide-bandgap semiconductors and the Curie temperature(Tc) in DMSs increases with the increase of band gap width. Being one of wide-bandgap semiconductors, Si C has been attracted considerable attentions due to their wonderful physical properties, such as high-power, high-temperature and high-frequency applications. But Investigation of Si C diluted magnetic semiconductors is not thorough.So it is important to carry out the Si C dilute magnetic semiconductor research in the way of theory and application.In this paper,Ni-doped,Ni/N and Ni/Al co-doped Si C films were fabricated on Si(100) substrates by RF-magnetron sputtering. Thehe local structure,magnetic and transport properties of the films were investigated in detail.The influence of annealing and doped concentration on the local structure, magnetic and transport properties of the Ni-doped Si C films were investigated in detail. the films form the structure of 3C-Si C with the process of annealing.After 800 ℃annealed, the doped Ni atoms substitute for the C sites of 3C-Si C lattice and no traces of any Ni-related secondary phase are detected. After 1200℃ annealing, the crystal quality of Ni-doped Si C films is improved and the Ni2 Si secondary phase is formed. The doped Ni atoms are Ni2+ in as-deposited and annealed films. All the films show the p-type semiconductor behavior.For the as-deposited and 800℃ annealed films, the transport properties are governed by Mott variable range hopping behavior. For the 1200℃ annealed film, the transport mechanisms can be achieved by the combination of the Mott VRH model in the low temperature range and the hard band gap hopping in the high temperature range. All the films are ferromagnetic at 300 K. the saturation magnetization increases with the Ni-doped concentration and annealing increasing. It can be concluded that the observed room-temperature ferromagnetism in the films comes from bound magnetic polarons induced by defects.The influence of annealing and doped concentration on the local structure, magnetic and transport properties of the Ni/N co-doped Si C films were investigated in detail. the films form the structure of 3C-Si C with the process of annealing.After 800 ℃annealed, the doped Ni atoms substitute for the C sites of 3C-Si C lattice and no traces of any Ni-related secondary phase are detected. After 1200℃ annealing, the crystal quality of Ni-doped Si C films is improved and the Ni2 Si secondary phase is formed.Doped N atoms restrain the formation of 3C-Si C. The doped Ni/N atoms are Ni2+/ N3-in all the films. All the films turn the n-type semiconductor behavior. For the as-deposited and 800℃ annealed films, the transport properties are governed by Mott variable range hopping behavior. For the 1200 ℃ annealed film, the transport mechanisms can be achieved by the combination of the Mott VRH model in the low temperature range and the hard band gap hopping in the high temperature range. Doped N weaks localization effect may large the radius of magnetic polaron that augmenting ferromagnetism. All the films are ferromagnetic at 300 K. the saturation magnetization increases with the N-doped concentration and annealing increasing. It can be concluded that the observed room-temperature ferromagnetism in the films comes from bound magnetic polarons induced by defects and the interaction of VSi and N atoms.The influence of annealing and doped concentration on the local structure, magnetic and transport properties of the Ni/Al co-doped Si C films were investigated in detail. the films form the structure of 3C-Si C with the process of annealing. After 800 ℃annealed, the doped Ni atoms substitute for the C sites of 3C-Si C lattice and no traces of any Ni-related secondary phase are detected. After 1200℃ annealing, the crystal quality of Ni-doped Si C films is improved and the Ni2 Si secondary phase is formed. For the 1200℃ annealed films, Al9 Si phase is formed with the Al-doped concentration more than 2at%. Doped Al atoms stabilize the crystal structure of 3C-Si C. The doped Ni atoms are Ni2+in all the films. For the as-deposited films, a small part of doped Al atoms are Al clusters and the rest of them are Al3+.For the annealed films doped Al atoms are Al3+. All the films show the p-type semiconductor behavior. Doped Al increases hole carrier concentration. the formation of Al9 Si hole decreases carrier concentration, but still higher than hole carrier of only doped Ni.For the as-deposited and 800℃ annealed films, the transport properties are governed by Mott variable range hopping behavior. For the 1200℃ annealed film, the transport mechanisms can be achieved by the combination of the Mott VRH model in the low temperature range and the hard band gap hopping in the high temperature range. All the films are ferromagnetic at 300 K. the saturation magnetization increases with the Al-doped concentration and annealing increasing. It can be concluded that the observed room-temperature ferromagnetism in the films comes from bound magnetic polarons induced by defects.