On the photogalvanic effect in asymmetric quantum wells of different shapes

Abstract

In this work we studied the charge carriers' behaviour in quantum structures where the symmetry with respect to space coordinates and time-reversal symmetry are broken simultaneously. As the models of such structures we considered finite triangular as well as finite semi-parabolic quantum wells placed in external magnetic field. We have shown by numerical analysis that the energy spectra of charge carriers in such structures are anisotropic with respect to in-plane (transverse) motion ϵ n ( + k x ) ≠ ϵ n ( − k x ) . This leads to the anisotropy of charge carrier's in-plane momentum transfer which can be very naturally explained by introducing the concept of charge carriers ‘renormalized’ effective masses. The anisotropy of momentum transfer leads to interesting photo-galvanic effect, the anisotropy of photo-conductivity σ ( + k x ) ≠ σ ( − k x ) and as it follows from our calculations, the effect though not very great, could be measurable for the magnetic field of about few T.