First-principles study of electron dynamics with explicit treatment of momentum dispersion on Si nanowires along different directions

In this research, ground-state electronic structure and optical properties along with photoinduced electron dynamics of Si nanowires oriented in various directions are reviewed. These nanowires are significant functional units of future nano-electronic devices. All observables are computed for a distribution of wave vectors at ambient temperature. Optical properties are computed under the approximation of momentum conservation. The total absorption is composed of partial contributions from fixed values of momentum. The on-the-fly non-adiabatic couplings obtained along the <i>ab initio</i> molecular dynamics nuclear trajectories are used as parameters for Redfield density matrix equation of motion. The main outcomes of this study are transition energies, light absorption spectra, electron and hole relaxation rates, and electron transport properties. The results of these calculations would contribute to the understanding of the mechanism of electron transfer process on the Si nanowires for optoelectronic applications.

本研究综述了不同取向硅纳米线（Si nanowires）的基态电子结构、光学特性以及光致电子动力学过程。此类纳米线是未来纳米电子器件的关键功能单元。本研究在室温环境下，针对波矢分布计算了全部可观测物理量；光学特性的计算采用动量守恒近似方法，总吸收光谱由不同固定动量值的部分贡献叠加而成。沿从头算（ab initio）分子动力学核轨迹获得的即时非绝热耦合项，被用作雷德菲尔德（Redfield）密度矩阵运动方程的参数。本研究的核心成果包括跃迁能、光吸收光谱、电子与空穴弛豫速率以及电子输运特性。上述计算结果有助于理解硅纳米线在光电子应用中的电子转移过程机制。