Observation of Franz-Keldysh Oscillations in InP Self-Assembled Quantum Dot Systems

Abstract
Distinct Franz-Keldysh oscillations were observed in the nonlinear reflection spectra of heterostructures with InP self-assembled quantum dots measured by the pump-probe method. These oscillations showed the presence of a built-in electric field of about 30 kV/cm. The built-in electric field is considered to originate from the electric charge captured by the structural defects on the dot interface. The estimated areal density of the electric charge is about 2×1011 cm-2. Electroreflectance showed nonmonotonic changes with the change in applied bias.