Franz–Keldysh effect in a two-dimensional system

We report luminescence and photocurrent experiments on an InGaAs/GaAs quantum well in strong lateral electric fields. The fields are imposed with an interdigitated gate on the crystal surface that consists of an array of metal stripes with a 250 nm period. The small period allows generation of electric fields of about 105 V/cm by application of only 1.5 V at the gate electrodes. Strong subgap absorption and oscillations of the interband absorption as function of radiation energy are observed and discussed in view of the Franz–Keldysh effect. The resulting photo-I-V characteristic shows high potential for electro-optic applications.