Capacitance–voltage spectroscopy of post-growth annealed InAs quantum dots

We have modified the 300 K ground state emission wavelength of InAs quantum dots in the range from 1260 to 960 nm by varying the growth conditions or by post-growth annealing, respectively. The quantum dots were investigated by photoluminescence spectroscopy to determine the emission wavelength and by capacitance–voltage spectroscopy to obtain information on the electron–electron interaction. With increasing post-growth annealing temperature, the emission blue-shifts and the ground state Coulomb energy decreases from 19.4 to 14.5 meV. This is consistent with the out-diffusion of In during the annealing step resulting in a larger quantum dot with reduced In content. In comparison with post-growth annealing, we have employed the so-called “flush” technique involving partial overgrowth to blue-shift the quantum dot emission. In this case, the ground state Coulomb energy is almost independent of the emission wavelength. We attribute this to a reduced height of the quantum dot but unchanged lateral dimensions.