Growth rate effects on the size, composition and optical properties of InAs/GaAs quantum dots grown by molecular beam epitaxy

The effect of the InAs deposition rate on the properties of InAs/GaAs quant um dots (QDs) grown on GaAs (0 0 1) substrates by molecular beam epitaxy ha s been studied by scanning tunnelling microscopy (STM) and photoluminescenc e (PL). PL studies performed on GaAs capped QD samples show that the emissi on wavelength increases with decreasing growth rate, reaching a maximum aro und 1.3 mum, with the linewidth decreasing from 44 to 27 meV. STM studies o n uncapped dots show that the number density, total QD volume and size fluc tuation all decrease significantly as the growth rate is reduced. The obser ved shifts in the emission wavelength and linewidth are attributed to chang es in the QD size, size distribution and composition. (C) 2001 Elsevier Sci ence B.V. All rights reserved.