The SiNWs can be most significant structural units of optoelectronics and photovoltaic devices. The ground state structure, optical properties, and electron dynamics of Si nanowires (SiNWs) oriented in various crystallographic directions have been studied computationally by density functional theory (DFT). All observables are calculated for a distribution of wave vectors at ambient temperatures. Optical properties are computed under assumption of momentum conservation. Under this approximation, the total absorption spectrum is composed of partial contributions to absorption from fixed values of the momentum. The on-the-fly non-adiabatic couplings for electronic degrees of freedom are obtained along the <i>ab initio</i> molecular dynamics nuclear trajectories. These couplings are used as parameters for Redfield density matrix equation of motion, which helps to explore the photo-induced non-radiative processes in these SiNWs. The electron and hole relaxation time depends on the number of states available to occupy on the conduction band and valance band respectively. The performance of photovoltaic cells relies on the relaxation time of electron and hole at lower energy transitions.

<i>Ab initio</i> study of electron dynamics with explicit treatment of momentum dispersion on Si nanowires oriented in different directions

256th National Meeting (2018)

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Ab initio study of electron dynamics with explicit treatment of momentum dispersion on Si nanowires oriented in different directions