Simultaneous measurement of nanoprobe indentation force and photoluminescence of InGaAs/GaAs quantum dots and its simulation

Simultaneous measurement of the nanoprobe indentation force and the photoluminescence (PL) of In0.5Ga0.5As/GaAs quantum dots (QDs) is successfully achieved by introducing a specially designed loadcell into the nanoprobe indentation system. By using this improved system, the emission properties of self-assembled In0.5Ga0.5As/GaAs QDs under nanoprobe indentation are investigated under low temperature and high vacuum conditions. Energy shifts as large as 90 meV induced by nanoprobe indentation are observed in the QDs. Further, the increase in the emission energy of the QDs varies from peak to peak under the same indentation force. In order to clarify this mechanism, simulations are carried out based on a three-dimensional finite element and six-band strain-dependent k·p Hamiltonian. The simulation results are in good agreement with the experimental ones. The results of the nanoprobe indentation experiments show that the change in the position of the QD relative to the nanoprobe results in a variation in its energy shift rate. This dependence of the energy shift rate of a QD on its position is also validated by repeated indentation with horizontal scan experiment.