Carrier migration in structures with InAs quantum dots

Abstract

A spectrally and spatially resolved investigation of emission from InAs/GaInAs quantum dots is performed using confocal photoluminescence. Structures investigated included a single layer of InAs dots embedded in a Ga0.85In0.15As quantum well and InAs dots embedded directly in GaAs. Excitation is performed at different wavelengths to provide selective excitation of either the quantum well or both the well and GaAs barrier. No noticeable lateral migration is observed under 900 nm wavelength pumping generating carriers only inside the quantum well. This is an indication that the diffusion of excess carriers is strongly suppressed by capture into dots. When GaAs surrounding material is also excited, the migration of excitation power occurs over 1.65 μm at the ground state of the quantum dots and 1.2 μm at the first-excited state. Saturation of the ground, first-, and second-excited state bands, when the carriers are generated only in quantum well, is also studied.