Influence of Coulomb interaction on interband photogalvanic effect in semiconductors

TL;DR

This paper develops a theoretical model to analyze how Coulomb interactions influence the interband photogalvanic effect in noncentrosymmetric semiconductors, highlighting the dominance of ballistic photocurrent over shift current.

Contribution

It introduces a comprehensive theory incorporating Coulomb interactions into the calculation of ballistic and shift contributions to the photogalvanic effect using a two-band Dirac Hamiltonian.

Findings

Ballistic photocurrent significantly exceeds shift current in typical semiconductors.

The ratio of shift to ballistic current is proportional to the Bohr radius over the mean free path.

Coulomb interactions play a crucial role in determining the magnitude of the photogalvanic effect.

Abstract

The ballistic and shift contributions to the interband linear photogalvanic effect are calculated in the same band structure model of a noncentrosymmetric semiconductor. The calculation uses a two-band generalized Dirac effective Hamiltonian with the off-diagonal components containing $\mathbf{ k}$-dependent terms of the first and second order. The developed theory takes into account the Coulomb interaction between the photoexited electron and hole. It is shown that in typical semiconductors the ballistic photocurrent $j^{({\rm bal})}$ significantly exceeds the shift current $j^{({\rm sh})}$: the ratio $j^{({\rm sh})}/j^{({\rm bal})}$ has the order of $a_B/ \ell$, where $a_B$ is the Bohr radius and $\ell$ is the mean free path of photocarriers due to their quasi-momentum scattering.