Growth of InAs bilayer quantum dots for long-wavelength laser emission on GaAs

The authors reported the growth of asym. InAs bilayer quantum dots (QD) on GaAs substrate by MBE. A combination of different InAs growth rates (GR) for the 2 QD layers was used, resp., to increase QD d. and extend photoluminescence (PL) emission wavelength. A high GR used for the 1st layer guarantees a high QD d.; while a low GR used for the 2nd layer helps to extend the PL emission wavelength due to the dot size increase, which was confirmed by TEM and PL measurements. This kind of QDs is very sensitive to post-growth annealing procedure due to the dot size increase. By appropriately choosing the growth parameters, InAs bilayer QD laser diodes embedded in a conventional AlGaAs/GaAs waveguide structure were demonstrated. The devices yielded the lowest ever reported threshold c.d. of 134 A/cm2 in the range of 1.5 micro m wavelength for GaAs-based lasers. [on SciFinder (R)