Excitonic effects on dielectric properties of solids in a uniform electric field

Abstract

The imaginary part of the dielectric function for excitonic transitions and different types of critical points of a solid in a uniform electric field are presented in a closed form. The time-dependent Schrödinger equation, with a time-dependent gauge for the applied electric field which includes the electron-hole interaction forces is treated within the effective-mass approximation. In the weak fields and using the two-band approximations, the results can be expressed in terms of Airy functions. The peak position of the exciton lines is found to shift to lower energies and then move to higher energies as the electric field increases. The amplitude of the peak decreases as the electric field increases. The electron-hole interaction can be neglected in calculating the electric-field-induced change of the dielectric constant, when the applied electric field is much larger than the effective field of the electron-hole interaction. © 1971 The American Physical Society.