Multiple quantum wells and laser structures containing InAs quantum dots grown by molecular-beam epitaxy

InAs quantum dots were formed by depositing monolayers of InAs on GaAs, cov ered with InGaAs, and hanged with GaAs barriers. This formed a single quant um well in the present study, as grown by molecular-beam epitaxy. Both mult iple quantum wells (MQW) and lasers containing such layers were studied. Fo r the MQW structure, the InAs layer thickness affected both the wavelength and intensity of the photoluminescence measured. With increasing InAs thick ness, the wavelength changed from about 1.0 to 1.3 mum, with an increasing photoluminescence intensity. The dot size also depended on the InAs layer t hickness, ranging from 5 to 20 nm as: analyzed by cross-sectional transmiss ion electron microscopy. The photoluminescence intensity showed different d ependence on n- and p-dopnnts, being reduced by the Si doping, but enhanced by the Be-doping. Pulsed lasing at room temperature was observed for the b road area laser fabricated, with a threshold current density of 2 kA cm(-2) , at an emission wavelength of 1.06 mum. The effect of growth conditions on the lasing characteristics is also discussed. (C) 2001 Published by Elsevi er Science B.V.