High quality quantum dots fabricated by molecular beam epitaxy

Damage free quantum dots have been fabricated directly using molecular beam epitaxy. Excellent photoluminescence has been obtained and is attributed to the absence of the non-radiative recombination centers and the enhanced oscillator strength for exciton recombination due to the confinement of quantum dots. The size variation of the quantum dots has been estimated from the width of the emission peak of low temperature photoluminescence (PL). A variation of only +/- 10 Angstrom is obtained. The existence of the quantum dots has also been verified directly from the image of the dots using atomic force microscopy. The image sizes of the quantum dots agree with that estimated from the PL blue shift.