Longitudinal Stark Effect in Parabolic Quantum Dots

We present an experimental and theoretical investigation of the longitudinal quantum confined Stark effect in strain-induced parabolic InGaAs quantum dots. The electric field is applied in the plane perpendicular to the growth axis (quantum well plane), through a sub-micron gap opened in a metallic contact, which contains just a few dots. The changes in the microphotoluminescence (µ-PL) spectra were measured versus the bias, at low temperature. Due to the device geometry, the electric field profile in the gate is not constant resulting in an asymmetric Stark effect as a function of the applied field polarity. Calculations of the field profile in the conatct gap and of the distorsion of the parabolic-like potential as a function of the applied field have been made in order to correlate the observed changes in the electro-optical properties of the dots with the carrier spill over and wavefunction modifications under electric field.