Highest density 1.3 μm InAs quantum dots covered with gradient composition InGaAs SRL grown with an As₂ source using molecular beam epitaxy

We propose a GaAs-based 1.3 μm InAs quantum dot (QD) structure for optical devices that uses a novel gradient composition strain reducing layer (GC-SRL) and dimeric arsenic (As₂). 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 μm InAs QDs that employ AS₂ are different from those of QDs that use AS₄. Our optimum structure exhibits the first room temperature emission of over 1.3 μm with a linewidth of 22 meV and a high density of over 1.1×10¹¹ cm^-2 using only a GC-SRL. We were also able to achieve a very high density of 3.3× 10¹¹ cm^-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 μm on a GaAs substrate for use in fiber communications.