One-phonon resonant Raman scattering in a semiconductor nanowire in presence of an external homogeneous electric field

Abstract

In this work, a theory of one-phonon resonant Raman scattering model for a cylindrical symmetry semiconductor nanowire long enough to be considered infinite in the presence of a homogeneous external electric field in transversal direction to the axis of the nanowire was developed. We considered $T=0K$ and a nanowire with infinite potential barrier. Moreover, parabolic bands have been assumed; the conduction band being completely empty, and a completely full valence band. Thus, the mathematical expressions of the Raman scattering differential cross section and the Raman efficiency have been obtained. In the case of electron-phonon interaction, the free-standing wire model was used. For the calculation of the electron states a model taking into account the conditions imposed by the electric field was used, which was assumed as valid for weak fields regarding confinement. To illustrate the results, the nanowire made of GaAs with a zinc-blende-type structure was considered. It was found that the presence of the electric field caused an increase in Raman efficiency. In addition, it was observed that the electric field caused the appearance of singularities in the Raman spectra due to the breaking of the selection rules for the creation and annihilation of the electron-hole pair, and the emission of non-longitudinal optical phonons was also verified.