Influence of the GaAs substrate thickness on the photoluminescence of an InP/AlGaInP quantum dot membrane

Modern semiconductor device technology expands to new application fields and increasing integrability even to hybrid system approaches. Thus, membrane technologies emerge to be a new standard for light-emitting devices as well. However, the fabrication of membranes often results in a shift of the emission wavelength of the active region compared to the as-deposited structure, especially when containing quantum dots (QDs). In this study, we investigate the wavelength shift of an AlGaInP heterostructure with InP QDs during the GaAs substrate removal step. For this, the substrate of a fivefold InP QD layer is selectively etched in such a way that a single sample provides areas with different remaining substrate thicknesses in a range within 1 μm. With photoluminescence measurements, a continuous blueshift of the emission spectrum of the QD ensemble can be observed. We explain these findings by the change of the strain within the entire structure, which impacts the confinement energies within the QDs.