B-Al共掺杂3C-SiC的第一性原理研究

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. 关键词： 3C-SiC B-Al共掺杂 电阻率 第一性原理

First principle study on B-Al co-doped 3C-SiC

The lattice parameters, band structure, density of states, effective mass, carrier concentration and electrical resistivity of 3C-SiC in different doped forms (undoped, B-doped, Al-doped and B-Al co-doped) are calculated using the plane wave ultrasoft pseudopotential based on density functional theory. Calculations indicate that as the B or Al replaces Si atoms, both the conduction band and valence band shift to higher energy level. The top of valence band shifts quicker, resulting in the decrease of the band gap. B-Al co-doped 3C-SiC shows the narrowest bandgap while the pure one has the widest. Effective mass of B-doped 3C-SiC decreases but that of Al-doped 3C-SiC increases; while B-Al co-doped 3C-SiC effective mass, whose value approaches to the undoped, can be understood in terms of different compensation. As the acceptor impurities, B and Al will greatly increase the carrier density of valence band top, and the carrier density of the co-doped is three times as Large as the B-doped or Al-doped 3C-SiC. In addition, B-Al co-doping has the lowest resistivity among the four doping forms displaying its significant advantages in electrical property.
Keywords： 3C-SiC B-Al codoping electrical resistivity first principles