Selective Self-Formation of InAs Quantum Dots on Strained InGaAs Layers by Molecular Beam Epitaxy

InAs was grown on a strained InGaAs/GaAs(001) layer by molecular beam epitaxy. The critical thickness and the dot structure of the InAs were investigated as a function of the thickness of the InGaAs base layer. The critical thickness of the InAs layer increased with decreasing residual strain of the InGaAs surface. Chains of self-formed InAs dots were partially observed along the [110] direction. This selective self-formation of InAs dots was caused by a strain distribution and an anisotropy of the residual strain on the InGaAs surface.