Spectroscopic studies of self-assembled InAs and In0.5Ga0.5As quantum dots

We investigate a wide range of structures with InAs and (InGa)As self-organised quantum dots (QDs) embedded in a GaAs matrix and grown on a variety of substrates, including (100), (311)A and (311)B. There is a significant qualitative narrowing of the typical QD photoluminescence (PL) linewidth for QDs on the high index planes. Linewidths as narrow as 13 meV can be achieved, about a factor of 4 narrower than previously reported. Microscopic structural investigations of these layers and the dependence of the PL spectra on magnetic fields up to 42 T are also reported. From the diamagnetic shift of the PL line, we estimate the spatial extent of the carrier wave function in the dots which we compare with their geometrical size. Using this information, we develop a qualitative model to explain the narrow PL of the QDs grown on (311)A and B planes.