Co掺杂4H-SiC电子结构的第一性原理计算

First-principles calculations of electronic structures in Co doped 4H-SiC

采用基于密度泛函理论的第一性原理平面波赝势方法研究Co掺杂4H-SiC的电子结构和磁性。计算结果表明:Co掺杂引入了空穴,产生自旋极化。Co掺杂4H-SiC的价带顶和导带底分别由Co的3d态和C的2p态占据,而Si的2p轨道作用较小。通过计算10种可能的掺杂位置,确定了铁磁性最稳定的组态。由于Co_0:3d-C:2p-Co_6:3d链之间存在一定的耦合关系,Co与C原子间强烈的d-p轨道杂化使得Co掺杂4H-SiC处于较稳定的铁磁基态。Co的引入使得基体空穴增加,缺陷调节下空穴载流子的远程交换(RKKY)机制导致了铁磁性的出现。

Electronic and magnetic properties of Co doped 4H-SiC are researched by use of the first-principle plane wave pseudo-potential method based on density functional theory. Ten kinds of doping position were calculated and the most stable configuration was found out. The calculation results show that spin-polarization appears in one Co atom doped 4H-SiC, which is due to the introduction of vacancy. The top of valence band and the bottom of the conduction band are mainly contributed by Co-3 d, C-2 p orbitals, with small contribution of Si-2 p. Ferromagnetism order is activated by Co doping via a Co0：3 d-C：2 p-Co6：3 d coupling chain. Hybridization occurs between p-d orbitals. The doped Co ion will induce additional holes carrier into the 4H-SiC. Therefore, the mechanisms for stabilizing the ferromagnetic state in Co doped 4H-SiC based on defect interaction and Ruderman-Kittel-Kasuya-Yosida（RKKY） interaction.