Optimisation of MBE growth conditions for InAs quantum dots on (001) GaAs for 1.3 mu m luminescence

We present a study of the optimised growth conditions for InAs quantum dots (QDs) grown on GaAs substrates by solid source molecular beam epitaxy (SSM BE). Growth conditions for best luminescence intensity and linewidth were f ound within narrow windows of substrate temperature (500 520 degreesC) and nominal InAS layer thickness (3.3-3.7 monolayers). The emission wavelength of such InAs QDs capped by GaAs was around 1.24 mum. However. this is redsh ifted to 1.3 mum or more by capping the InAs QDs with a thin layer of InxGa 1-xAs. The results show that both In content and thickness of the capping l ayer can be used to tune the emission wavelength. Atomic force microscopy i mages show that the surface recovers to two-dimensional when depositing In0 .2Ga0.8As while remaining three-dimensional when depositing In0.4Ga0.6As. ( C) 2001 Elsevier Science B.V. All rights reserved.