In situ CBrCl3 etching to control size and density of InAs/GaAs quantum dots

The effects of in situ CBrCl3 etching of InAs quantum dots (QDs) grown on GaAs by metal-organic vapor phase epitaxy have been studied in detail for control of the size and density of InAs dots. The width and height distributions of InAs dots after etching for various etching times and CBrCl3 flow rates suggest that the CBrCl3 etching is ineffective in decreasing the width but effective in decreasing the height. The density of the InAs dots are controlled over more than 2 orders of magnitude by changing the flow rate from 0 to 22 μmol/min. Although the atomic force microscopic (AFM) image for 22 μmol/min does not show any dots because of a detection limit, the PL peak associated with the QDs evidences presence of dots whose density is less than 2×106 cm−2. Such a low density is suitable for single QD device applications. The PL spectra for various CBrCl3 flow rates suggest less effective etching of the Ga-rich InGaAs wetting layer and the decreased size of QDs with the increased flow rates.