Impact of an InxGa1–xAs Capping Layer in Impeding Indium Desorption from Vertically Coupled InAs/GaAs Quantum Dot Interfaces

This study describes the effect of a thin GaAs spacer of 4.5 nm thickness in a bilayer-coupled InAs quantum dot (QD) heterostructure. Here, we report the first demonstration of InAs/GaAs QDs capped by self-assembled InxGa1–xAs layers. Self-assembled InxGa1–xAs layers were introduced into each intermediate layer across the interface of InAs QDs and the GaAs layer in a vertical-coupled bilayer QD (VCBQD) heterostructure to prevent indium desorption from the QDs. A change in the indium content in the seed-layer InAs QDs changes the self-assembly position and modifies the InxGa1–xAs layer thickness. A theoretical approach was presented to study the formation of self-assembled InxGa1–xAs layers at each strain-free layer. We showed that the strain energy at the second intermediate (ezz2) layer is greater than that at the first intermediate (ezz1) layer; ezz2 depends on the vertical strain channel length. The impact of the InxGa1–xAs layer thickness on the strain energy was studied using high-resolution transmis...