Carrier dynamics in InAs quantum dots investigated by current transient response to quasi-resonant interband excitation

Abstract

We have investigated the photocurrent transient response of planar metal–semiconductor–metal (MSM) structures containing a single layer of self-assembled InAs quantum dots (QDs) embedded in different matrices of GaAs or InGaAs. Growth conditions are such that ground state transition energies correspond to the wavelength range of 1.2–1.3 μm. Electron–hole pairs are created in the QDs, due to a quasi-resonant interband excitation, allowing for direct observation of the carrier dynamics under lateral electric field. Results prove the reasonable detection capability of one layer of QDs in a common photodetector structure with time responses of the order of 10 ps. A long tail, about 100 ps, but at a small fraction of the peak response amplitude is also observed.