Large InAs/GaAs quantum dots with an optical response in the long-wavelength region

Uncapped InAs/GaAs quantum dots with an average height of 14 nm were obtained combining a low growth rate (0.01 ML/s) and a high substrate temperature (520 °C) during molecular beam epitaxy of InAs on GaAs(0 0 1). This achievement of a very narrow distribution (∼3%) of large coherent islands was made possible by the suppression of the nucleation of relaxed structures. When GaAs-capped, such quantum dots emit light well-above 1.2 μm (at 1.4 K), exceeding the long-wavelength emissions obtained so far by similar samples.