Energy states and carrier transport processes in metamorphic InAs quantum dots

Photoluminescence excitation spectroscopy is used to probe energy states and carrier transport in InAs quantum dot structures grown on InGaAs metamorphic layers, designed for room temperature emission at 1.3, 1.4, or 1.5 lm. The dominant spectral feature is shown to arise from the partially relaxed InGaAs confining layer. In structures with a low indium composition or thin InGaAs layer, a clear wetting layer feature is observed which acts as the dominant reservoir for carriers thermally excited from the quantum dots. Structures with high indium composition and/or thick InGaAs lack a wetting layer and carriers escape directly to the Physics. [http://dx.doi.org/10.1063/1.4744981]