Study of the photoluminescence properties of subcritical InAs/GaAs quantum dots formed onto structured substrates

In this work we study the optical properties of InAs quantum dots grown on the GaAs(001) nanostructured surfaces at sub-critical thickness of deposition. For substrate nanostructuring we used technique based on two-stage thermal  desorption of native GaAs oxide under molecular arsenic flux. The results of experimental studies showed the possibility of quantum dots formation on structured surfaces at equivalent deposition thicknesses in the range of 0.5–1.5  ML. In this case, quantum dots are formed predominantly in nanoholes on the surface and are high inhomogeneous in size. At the same time measurements by photoluminescence spectroscopy showed broad (900–1100 nm)  emission spectrum for quantum dot only for sample with 1.5 ML of InAs. We hypothesize that at smaller thicknesses, the formed quantum dots become smaller than the minimum acceptable sizes due to segregation effects during  overgrowth. The use of a structured surface also makes it possible to suppress the wetting layer formation – in the photoluminescence spectra there are only lines of platelets, apparently formed on morphological inhomogeneities  outside the holes.