尺寸相关的弹性常数对应变硅纳米线电学性质的影响

从Keating模型出发，基于离散化思想建立了计算单晶硅纳米线弹性常数和杨氏模量的半连续原子晶格力学模型. 从微扰理论和形变势理论出发，采用有限差分方法建立了计算不同晶向应变硅纳米线价带结构的数值模型. 结合上述的两个计算模型，进而应用经典弹道传输模型研究了轴向应力和弹性常数对p型硅纳米线弹道晶体管电学特性的影响. 研究结果表明，硅纳米线的弹性常数和杨氏模量呈现尺寸效应，该结果与分子动力学的模拟结果具有很好的一致性. 同时发现尺寸相关的弹性常数对硅纳米线晶体管输运电流的影响强烈依赖于单轴应力对输运电流的影 关键词： 应变硅纳米线 弹性常数 弹道电流 价带结构模型

Effect of size-dependent elastic constants on electrical properties of strain silicon nanowires

Starting from the Keating model, a semi-continuum atomistic lattice model, with directly taking into account the discrete nature in width and thickness direction, is proposed to calculate the elastic constants and Youngs modulus of single crystal silicon nanowires (SiNWs). Based on the six-band k·p theory and the deformation potential concept, and taking into account the quantum-size effect and spin-orbit coupling, a numerical model for the valence band structures of SiNWs in various transport orientations is established by using the finite difference method. Then we use a top-of-the-barrier ballistic field-effect transistor (FET) model to investigate the effects of the uniaxial stress and the elastic constants on ballistic transport properties of the p-type SiNW FETs in combination with the calculation results from the two models mentioned above. It is found that the elastic constants and Youngs modulus of the SiNW are highly size-dependent, which is in good agreement with the available molecular dynamics result. Furthermore, our calculations indicate that the effect of size-dependent elastic constants on ballistic transport current of the SiNW FET strongly depends on the effect of the uniaxial stress on ballistic transport current, because when the uniaxial stress induces a significant change in valence band structures of SiNWs, the size-dependent elastic constants can obviously modify the valence band structure.