Manipulation of the homogeneous linewidth of an individual In(Ga)As quantum dot

By application of external electric field, we demonstrate the ability to controllably manipulate the homogenous linewidth of exciton transitions in a single self-assembled In(Ga)As quantum dot (QD). Complementary emission (photoluminescence) and absorption (photocurrent) measurements are used to probe directly the competing processes of radiative recombination and carrier tunnelling escape from the dot. At high electric fields (greater than or similar to100 kV/cm) the exciton line shape is lifetime (homogenously) broadened with mesoscopic broadening effects arising from coupling of the QD to its electrostatic environment determining the low field line shape.