Observation of built-in electric field in InP self-assembled quantum dot systems

Strong Franz–Keldysh oscillations were observed in the nonlinear reflection spectra of heterostructures with InP self-assembled quantum dots. These oscillations manifest a built-in electric field of about 30 kV/cm. We propose that this field originates from electric charge captured by the intrinsic defects on the dot interface. The presence of acceptor-like intrinsic defect states is found to be a general feature of the InP/InGaP interface but was not observed in other structures with quantum dots such as InAs/GaAs.