Electronic structure and magnetic properties of transition-metal-doped3Cand4Hsilicon carbide

Abstract

We report density-functional calculations using the full-potential linearized muffin-tin orbital method on early first row transition-metal-doped silicon carbide in cubic ͑3C͒ and hexagonal ͑4H͒ polytypes. The transition energy levels in the gap for Ti, V, and Cr are compared with the available deep level transient spectroscopy and photoluminescence experiments. Our calculation shows that the Ti impurity is active for 4H but not for 3C, while V and Cr impurities are active for both polytypes. The magnetic interactions are very different for Cr and Mn. Cr shows a very local exchange interaction that decays rapidly after second nearest neighbors, which is similar for different polytypes and different sites. The exchange interaction for Mn is quite long range and is very sensitive to the location of the Mn pairs.

Multiple Magnetic States of Silicon Carbide Diluted Magnetic Semiconductors

“…Theoretical ab initio results for TM-doped SiC were also somewhat contradictory, predicting Cr and Mn to be ferromagnetic at the Si sites with different values of the magnetic moment and magnetic coupling energy, while Fe was found to be nonmagnetic in some cases and magnetic in others. [10][11][12][13][14][15] No spin polarization was reported for Co-doped and Ni-doped SiC. 10,11 The results were also found to be sensitive to the particular calculation technique employed.…”

“…In the DMS systems with TM concentrations of several percent, the Fermi level position and impurity charge states are determined by the TM impurity itself, if no other impurity is present in the semiconductor in a concentration comparable to that of the TM so as to alter the Fermi level position. Results of recent calculations of TM energy levels in SiC 11,13 indicate that, if the material is doped by a TM only in these typical concentrations, all impurities under study here are expected to be in their neutral charge states.…”

Asymmetric Split-Vacancy Defects in SiC Polytypes: A Combined Theoretical and Electron Spin Resonance Study

“…[25]. According to our HSE06 calculation, the position of the fully occupied eð2Þ level in the spin-up channel (S ¼ 1, M S ¼ 1) will shift down with respect to E V by about 1.0, 0.3, 0.1 eV compared to PBE values for M ¼ Cr; Mo; W, respectively, whereas the gap ''opens'' by 0.93 eV.…”

“…The early first row M Si defects were already analyzed in Ref. [25] where local density approximation was applied with a scissor operator in 3C-and 4H-SiC polytypes. We briefly give the main finding: the d states of M impurity will split in T d and C 3v crystal fields of 3C and hexagonal polytypes, respectively.…”

Soft X-ray Absorption and Photoemission Studies of Ferromagnetic Mn-Implanted 3C-SiC

“…Since most of the implanted Mn atoms formed silicide clusters in the present study, the content of substitutional Mn in SiC may be small. A recent density functional calculation [25] has pointed out that substitutional Mn atoms at the Si site prefer long-range ferromagnetic coupling in 3C-and 4H-SiC. Fabrication of SiC by molecular-beam epitaxy with high crystallinity have been reported [26] and an incorporation of a substantial amount of Mn into substitutional sites using other techniques such as a low-temperature-molecular-beam epitaxy may be an interesting possible route to fabricate SiC-based ferromagnetic semiconductors.…”