Enhancement of photoluminescence from near-surface quantum dots by suppression of surface state density

We report the functionalization of semiconductor nanostructures near the surface with the self-assembled monolayer of octadecylthiol (ODT). In the first part of this study, photoluminescence properties of the near-surface quantum dots and quantum wells grown on GaAs [100] substrates were investigated as a function of the distance to the surface, and the luminescence signals were also systematically compared in terms of the confinement potential. In the second part, the ODT monolayer was deposited on the nanostructures based on indium arsenide quantum dots (InAs QDs). The monolayer deposition resulted in a significant enhancement in the photoluminescence from the QDs, which can be attributed to the effective suppression of the surface state densities by arsenide sulfide coupling. It is noteworthy that the enhancement in the luminescence signal was more significant for QDs closer to the surface. Since the hydrophobic surface of the monolayer can be functionalized with polymer films and model cell membranes, this strategy is applicable for the design of local detectors in the very proximity of the surface.