Limits of In(Ga)As/GaAs quantum dot growth

For the formation of large In(Ga)As/GaAs quantum dots, aiming at emission wavelengths of 1.3 μm, strategies like the use of strain reducing diluted InGaAs capping layers or the growth of InAs quantum dots embedded in InGaAs quantum wells are very promising. Using cross‐sectional scanning tunneling microscopy we observed for both concepts an increased quantum dot size, but also defective quantum dots, characterized by a material hole or so‐called nanovoid. The process of such nanovoid formation is investigated in detail, considering the strain and the limited growth kinetics during capping. The existence of nanovoids impressively shows the limitations of growing larger and thus more strained quantum dots. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)