Wannier Exciton in an Electric Field. I. Optical Absorption by Bound and Continuum States

TLDR

The study investigates how electric fields influence optical absorption by Wannier excitons in both bound and continuum states. The authors outline a general normalization procedure for wave functions with continuous eigenvalues. They demonstrate that using dimensionless parameters makes the eigenvalues field‑independent, and that electron‑hole interactions amplify field‑induced oscillations near M0 edges while suppressing them near M3 edges, potentially masking M3 edges in electroreflectance measurements.

Abstract

A comprehensive study of electric field effects on optical absorption by Wannier excitons is presented, showing field effects on both bound and continuum states. The calculations and results have been simplified by defining appropriate dimensionless parameters such that the eigenvalues are independent of field when expressed in terms of these parameters. A general normalization procedure for wave functions with continuous eigenvalues is outlined. The effect of the electron-hole interaction on the electric-field-induced oscillations is demonstrated, with the result that the electron-hole interaction enhances these oscillations near an ${M}_{0}$-type edge (positive effective masses) and quenches these oscillations near an ${M}_{3}$-type edge (negative effective masses). This effect would inhibit the observation of ${M}_{3}$-type edges in electroreflectance.