Volmer-Weber and Stranski-Krastanov InAs-(Al,Ga)As quantum dots emitting at 1.3 mu m

Quantum dots (QDs) formed on GaAs(100) substrates by InAs deposition follow ed by (Al,Ga)As or (In,Ga,Al)As overgrowth demonstrate a photoluminescence (PL) peak that is redshifted (up to 1.3 mum) compared to PL emission of GaA s-covered QDs. The result is attributed to redistribution of InAs molecules in the system in favor of the QDs, stimulated by Al atoms in the cap layer . The deposition of a 1 nm thick AlAs cover layer on top of the InAs-GaAs Q Ds results in replacement of InAs molecules of the wetting layer by AlAs mo lecules, leading to a significant increase in the heights of the InAs QDs, as follows from transmission electron microscopy. This effect is directly c onfirmed by transmission electron microscopy indicating a transition to a V olmer-Weber-like QD arrangement. We demonstrate an injection laser based on this kind of QDs. (C) 2000 American Institute of Physics. [S0021-8979(00)0 9323-3].