Observation of Franz-Keldysh oscillations in InP self-assembled quantum dot systems

Distinct Franz-Keldysh oscillations were observed in the nonlinear reflecti on spectra of heterostructures with InP self-assembled quantum dots measure d by the pump-probe method. These oscillations showed the presence of a bui lt-in electric field of about 30 kV/cm. The built-in electric field is cons idered to originate from the electric charge captured by the structural def ects on the dot interface. The estimated areal density of the electric char ge is about 2 x 10(11) cm(-2-). Electroreflectance showed nonmonotonic chan ges with the change in applied bias.