Ultrafast electron capture into p-modulation-doped quantum dots

Electron and hole relaxation kinetics are studied in modulation-doped InAs quantum dots using femtosecond time-resolved photoluminescence experiments. We demonstrate that, as a result of doping, carrier relaxation from the barrier layers to the quantum dot ground states is strongly enhanced due to rapid electron–hole scattering involving the built-in carrier population. Results for p-doped quantum dots reveal a threefold decrease in the room-temperature electron relaxation time relative to corresponding undoped quantum dots. Our findings are promising for the development of high-speed, GaAs-based quantum dot lasers with modulation speeds in excess of 30GHz.