Exciton radiative lifetime controlled by the lateral confinement energy in a single quantum dot

We report on time-resolved measurements on single GaAs quantum dots formed at the interface fluctuation of a GaAs/AlGaAs quantum well. We measure exciton radiative lifetimes as short as 100 ps, demonstrating that monolayer fluctuation quantum dots have larger oscillator strength than any other III-V or II-VI semiconductor quantum dots. Studying various single quantum dots, we demonstrate that the oscillator strength of a quantum dot is controlled by its lateral confinement energy.