Electric field effects on optical absorption by excitons in semiconductors

The effect of an electric field on exciton oscillator strengths is calculated for both bound and continuum states. The calculation is performed for Wannier excitons using the effective~mass approximation at both the Mo and M3 type edges. In comparison with single-particle theory, the inclusion of the electron-hole interaction increases the oscillator strengths at the Mo edge and at the same time enhances and shifts the Franz-Keldysh type oscillations near the edge. The effect of the electron-hole interaction on the M3 edge is to decrease the oscillator strengths and the amplitude of the Franz-Ke1dysh type oscillations near the edge. It is also shown that, for small electric fields, the splittings and shifts of the bound states with electric field are in accordance with the well known perturbation treatment of the Stark effect.U of I OnlyThesi