二维6H-SiC光学特性的应变调控

为了减小6H-SiC的带隙、提高对可见光的吸收效率和载流子迁移速率，采用第一性原理研究了应变对6H-SiC的能带结构、光学吸收系数、载流子迁移率以及光催化特性的影响。结果表明：应变能够降低6H-SiC的导带底，但对价带顶没有影响，导致带隙减小。随着应变的增加，吸收曲线向低能级方向移动，即发生红移，有利于可见光的吸收。施加应变后空穴的载流子迁移率提高，有利于载流子移动，且空穴的载流子迁移率是电子的2.5倍，有利于空穴和电子的分离。综合应变对带隙大小、带边位置的影响可知，应变在±2%、±4%时对可见光的吸收以及光催化制氢最有效。综上所述，应变能够对6H-SiC的光学吸收和光催化特性有很好的调控作用。

Strain regulation of optical properties of 2D 6H-SiC

In order to reduce band gap of 6H-SiC, improve the absorption efficiency of visible light and carrier mobility, the effects of strain on the band structure, optical absorption coefficient, carrier mobility and photocatalytic properties of 6H-SiC were studied based on the first principle. The results indicate that strain can reduce the conduction band minimum (CBM) of 6H-SiC, but has no effect on the valence band maximum (VBM), resulting in the reduction of band gap. With the increase of strain, the absorption curve moves to the low energy level (red shift), which is beneficial for the absorption of visible light. After the strain is applied, the carrier mobility of the hole is improved, which is conducive to the carrier movement, and the carrier mobility of the hole is 2.5 times that of the electron, which is conducive to the separation of the hole and the electron. According to the influence of strain on band gap and band edge position, the strain of ±2% and ±4% are the most effective conditions for visible light absorption and photocatalytic hydrogen generation. In conclusion, the strain can well regulate the optical absorption and photocatalytic properties of 6H-SiC.