Exciton Dephasing and Biexcitons in InAs Quantum Rhombic Disks

We study exciton dephasing and biexciton binding energy in InAs quantum rhombic disks by means of the highly sensitive heterodyne‐detected 2‐pulse photon echo. The exciton‐biexciton quantum beat is superposed on the photon echo decay, where the decay time and the beat period give the dephasing time of excitons and the biexciton binding energy, respectively. The dephasing times and biexciton binding energies are 31 ps and 3.4 meV for 3 monlayer InAs quantum rhombic disks and 41 ps and 4.1 meV for 4 monolayer InAs quantum rhombic disks. The dephasing time is shortened under the additional light exposure, suggesting the exciton‐exciton collision induced dephasing.