Simple theoretical analysis of the interband optical absorption coefficient in wide-gap semiconductors in the presence of an external electric field and its dependence on a longitudinal magnetic field

An attempt is made to present a simplified theoretical analysis of the interband optical absorption coefficient (OAC) due to a constant uniform electric field on the basis of the electron wave vector dependence of the optical matrix element (OME) for the incident photon energy, (ℏωℏω), below and above the band-gap (Eg). It has been found, taking n-GaAs as an example for numerical computation, that the expression of the OAC exhibits an exponential fall-off with the electric field and the photon energy without the consideration of the Wannier–Stark levels, which generally exists in a band due to the external electric field. The effect of a longitudinal magnetic field on the OAC is also studied on the basis of the fact that the transverse wave vector (k⊥) is quantized due to parallel magnetic field and is conserved in the interband optical transition of electrons. Similar results, such as singularity for the case ℏω