Sensitivity of the absorption edge to applied electric fields in GaAs-Ga1-xAlxAs superlattices

The dependence of light absorption on an applied electric field in GaAs-Ga1-xAlxAs superlattices is investigated theoretically for photon energies near the zero-field band gap. In the quantum-well limit, the results show that while the red shift is negligible the change in absorption with applied field for a given photon energy can be substantial. For nearly opaque barriers, the absorption coefficient at 100 kV/cm is about twice the zero-field value. As the barriers become thinner, the red shift is enhanced but the sensitivity is diminished. At the same time the increased coupling between the wells gives rise to Franz-Keldysh oscillations.