Formation of relaxed SiGe on the buffer consists of modified SiGe stacked layers by Si pre-intermixing

Electron microscopy of quantum dots

“…Overgrowth of such islands by a cap layer of a semiconductor with higher band‐gap often takes more than 8 nm without annealing before a completely flat surface is recovered (Joyce et al ., ; Liew et al ., ; Suseendran et al ., ; Krause et al ., ). The capping leads to flattening of the islands and some lateral diffusion of the larger atomic species from the buried islands into the surrounding barrier material (Steimetz et al ., ; Bischoff et al ., ; Chen et al ., ), which will be enhanced by subsequent annealing (Qiu et al ., ,b). The flattening changes the dot geometry, with a reduction in height leading to higher carrier confinement energies and thus a blue‐shift.…”