Comparative Study of Strain-Engineered InAs Quantum Dots via an In(subscript 0.23)Ga(subscript 0.77)As Matrix with Various Sequences and Thicknesses

Abstract

We have systematically studied the effect of an In(subscript 0.23)Ga(subscript 0.77)As layer with various thicknesses on self-assembled InAs quantum dots (QDs). The thickness of the In(subscript 0.23)Ga(subscript 0.77) As layer was varied in the range of 4 monolayers to 24 monolayers. In this work, four structures of the In(subscript 0.23)Ga(subscript 0.77) As- InAs combination were investigated: InAs QDs/GaAs, InAs QDs/ In(subscript 0.23)Ga(subscript 0.77)As/GaAs, In(subscript 0.23)Ga(subscript 0.77)As/InAs QDs/GaAs, and In(subscript 0.23)Ga(subscript 0.77)As/InAs QDs/ In(subscript 0.23)Ga(subscript 0.77) As/GaAs. It was found that the structural and optical properties of InAs QDs depend upon the thickness of the InGaAs layer. In addition, the InGaAs underlayer and capping layer have different effects on the optical properties of InAs QDs. This can be explained in that the InGaAs underlayer plays a role as an indium supplying layer, while the InGaAs capping layer acts as a strain reducing layer. As a result, the emission wavelength of InAs QDs can be tuned by introducing different In(subscript 0.23)Ga(subscript 0.77) As matrices.