Highest density 1.3 /spl mu/m InAs quantum dots covered with gradient composition InGaAs SRL grown with an As/sub 2/ source using molecular beam epitaxy

We propose a GaAs-based 1.3 /spl mu/m InAs quantum dot (QD) structure for optical devices that uses a novel gradient composition strain reducing layer (GC-SRL) and dimeric arsenic (As/sub 2/). Our proposed GC-SRL has a big advantage, such as reducing critical strain. We calculate the critical thickness of InGaAs GC-SRL for several In compositions. Also, The characteristics of 1.3 /spl mu/m InAs QDs that employ AS/sub 2/ are different from those of QDs that use AS/sub 4/. Our optimum structure exhibits the first room temperature emission of over 1.3 /spl mu/m with a linewidth of 22 meV and a high density of over 1.1/spl times/10/sup 11/ cm/sup -2/ using only a GC-SRL. We were also able to achieve a very high density of 3.3/spl times/ 10/sup 11/ cm/sup -2/ and a full width at half maximum of 23 meV for a triple-stack structure within the critical thickness. This result is promising as regards achieving a semiconductor laser and the other optical devices with QDs of over 1.3 /spl mu/m on a GaAs substrate for use in fiber communications.