Pauli-blocking imaging of single strain-induced semiconductor quantum dots

A case of local illumination photoluminescence (PL) spectroscopy is reported in which the limitation of spatial resolution due to exciton diffusion can be relaxed by making use of Pauli blocking of the level filling in semiconductor quantum dots. The PL originating from the first three confined level of eight individual dots is mapped out over an area of 1.4×1.4 μm. The spatial resolution of the PL of the lowest energy level is found to be limited to about 0.5 μm. In contrast, the mapping of the PL of the higher excited state shows a much improved spatial resolution of the order of 150 nm which is the instrument resolution.