硒化镉纳米线在应力作用下的第一性原理研究

First-principles Study on Cadmium Selenide Nanowires under Strain

基于密度泛函理论的第一性原理计算分析了不同横向尺寸的硒化镉(CdSe)纳米线在拉伸和压缩单轴应力作用下的能带结构、载流子(电子和空穴)的有效质量以及迁移率的变化。计算结果表明,CdSe纳米线在施加应变或改变横向尺寸时,均表现为直接带隙半导体。随着压缩应变(0%^-10%)和拉伸应变(2%~10%)的增加,CdSe纳米线的带隙逐渐减小,但横向尺寸小的纳米线的带隙相对宽些。导带底电子迁移率随着应变从-10%至10%变化而逐渐减小,而价带顶空穴迁移率在施加应变从4%至10%变化时也缓慢减小。直径为1.2nm的CdSe纳米线在施加的压缩应变为-10%时,电子和空穴迁移率最大,分别为2890cm^2·V^-1·s^-1和2273cm2·V^-1·s^-1。因此,横向尺寸较小的CdSe纳米线在合适的压应力调控下有望成为一种制备高性能新型纳米电子器件的候选材料。

A series of characteristics,such as the band structure,carriers(electrons and holes)effective mass and mobility,of cadmium selenide(CdSe)nanowires with different transverse dimensions under tensile and compressive uniaxial stress were analyzed by the first-principles calculation based on density functional theory.The results show that CdSe nanowires remain as the direct bandgap semiconductors while stress is applied or only the lateral dimensions are changed.As the compressive strain(0%-10%)and tensile strain(2%-10%)increase,the band gap of CdSe nanowires is gradually reduced.However,the nanowires with smaller lateral size have a relatively wider band gap.The electron mobility in conduction band minimum is gradually reduced with the strain from-10%to 10%,so does the hole mobility in valence band maximum with the strain from 4%to 10%.When the compressive stress of-10%is applied to CdSe nanowire with the diameter of 1.2 nm,the electron and hole mobilities reach their maximum,2890 cm 2·V^-1·s^-1 and 2273 cm 2·V^-1·s^-1,respectively.Therefore,CdSe nanowires with smaller lateral dimensions are expected to be good candidates for the preparation of high performance novel nanoelectronic devices under suitable compressive stress control.