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采用基于密度泛函理论的第一性原理平面波超软赝势法,计算了未掺杂,B,Al单掺杂和B-Al共掺杂的3C-SiC的晶格参数、能带结构、态密度、有效质量、载流子浓度和电阻率.计算结果表明:掺杂后导带和价带都向高能端移动,价带移动速度更快一些,使得禁带宽度都有一定程度的减小,其中B-Al共掺杂的禁带宽度最窄,纯净3C-SiC的禁带宽度最宽;B掺杂会减小价带顶空穴的有效质量,Al掺杂则反之,B-Al共掺杂补偿了二者的差异,和未掺杂的3C-SiC价带顶空穴的有效质量很接近.B和Al作为受主杂质,会极大地提高价带顶空穴载流子的浓度,而且B-Al共掺杂的3C-SiC的价带空穴浓度是B,Al单掺杂时的3倍.4种体系中,B-Al共掺杂得到的电阻率是最低的,同单掺杂相比具有明显的性能优势.
The first-principle plane wave super soft pseudopotential method based on density functional theory (DFT) was used to calculate the lattice parameters, the band structure, State density, effective mass, carrier concentration and resistivity.The calculated results show that both the conduction band and the valence band move to the high energy side after doping, and the valence band moves faster, which makes the forbidden band width reduced to a certain extent B-Al co-doped with the narrowest band gap, pure 3C-SiC widest bandgap; B doping will reduce the valence band peak cavity effective mass, Al doping on the contrary, B- Al co-doping compensates for the difference between them, which is very close to the effective mass of the undoped 3C-SiC valence caves.The acceptor impurities of B and Al can greatly increase the valence band top hole carriers , And the B-Al co-doped 3C-SiC has a valence band hole concentration of 3 times higher than that of single-doped B and Al. Among the four systems, the B-Al co-doped has the lowest resistivity , Compared with a single doping has obvious performance advantages.