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A comparative analysis is made of laser diodes based on Stranski-Krastanow (SK) and sub-monolayer (SML) InAs/GaAs quantum dots, emitting at about 940 nm. Owing to the better uniformity of sub-monolayer quantum dots, the SML QD laser surpasses the SK QD one in power characteristics. A maximum output power of 3.9 W and a peak power conversion efficiency of 59% have been achieved for SML QD 100 µm wide lasers at 10 • C.

Mechanism for improvements of optical properties of 1.3-μ m InAs ∕ GaAs quantum dots by a combined InAlAs -InGaAs cap layer J. Appl. Phys. 98, 083516 (2005); 10.1063/1.2113408 Tuning InAs/GaAs quantum dot properties under Stranski-Krastanov growth mode for 1.3 μm applicationsSuppression of temperature sensitivity of interband emission energy in 1.3-μm-region by an InGaAs overgrowth on self-assembled InGaAs/GaAs quantum dots Quantum dots ͑QDs͒ formed on GaAs͑100͒ substrates by InAs deposition followed by ͑Al,Ga͒As or ͑In,Ga,Al͒As overgrowth demonstrate a photoluminescence ͑PL͒ peak that is redshifted ͑up to 1.3 m͒ compared to PL emission of GaAs-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 QDs results in replacement of InAs molecules of the wetting layer by AlAs molecules, leading to a significant increase in the heights of the InAs QDs, as follows from transmission electron microscopy. This effect is directly confirmed by transmission electron microscopy indicating a transition to a Volmer-Weber-like QD arrangement. We demonstrate an injection laser based on this kind of QDs.

We demonstrate the possibility of extending the spectral range of luminescence due to InAs quantum dots (QDs) in a GaAs matrix up to 1.7 μm. Realization of such a long wavelength emission is related to formation of lateral associations of QDs during InAs deposition at low substrate temperatures (∼320–400 °C).