Growth and optical characterizations of InAs quantum dots on InP substrate: towards a 1.55μm quantum dot laser

摘要

The surface morphology changes associated with the formation of InAs/InP(311)B quantum dots grown according to a proposed growth procedure (double cap) have been investigated using atomic force microscopy (AFM). We show that the deposit of an InP capping layer thinner than the highest dot, followed by the annealing under phosphorous overpressure, leads to the smoothing of the growth front. It induces a drastic reduction of the dot height and of its dispersion. Transmission electron microscopy and photoluminescence experiments show a clear correlation between the QD height and the deposited InP layer thickness. Using this modified capping growth process, a 1.55μm emission wavelength with a narrower PL linewidth (50 meV) is achieved. Finally, we report ground state laser emission from QDs at 1.52μm, which supports the DC process for the fabrication of QD devices emitting in the 1.5μm range.