Evolution of self-assembled lateral quantum dot molecules

Bimodal optical characteristics of lateral InGaAs quantum dot molecules

“…However the template alone cannot be held responsible since excitons generated in the template layer are efficiently transferred to the overgrowth layer as demonstrated by Heitz et al [15] in a capped and regrown structure, but without the nanohole. We also measured PL spectra from a controlled nanohole template in the absence of QDMs and found broad PL signal centred at around 1.2 eV [11]. These rule out the possibility of the nanohole template being the sole factor responsible.…”

“…The temperature is further reduced to 470 1C and a thin (25-ML) GaAs capping layer deposited, transforming each seed QD into a $ 0.4-nm deep nanohole with mounds elongated along the [1-1 0] direction. Subsequent regrowth of 1.2-(sample A) or 1.5-ML (B) InAs at 470 1C results in the formation of QDMs, which is covered by 100-nm GaAs [11]. The formation of QDs and QDMs is confirmed in situ by real-time observation of streaks and spots in reflection high-energy electron diffraction patterns.…”

“…Lateral InGaAs quantum dot molecule (QDM) grown via the thin-cap-and-regrowth MBE technique is a structure with bimodal QDs whose size distributions can be well controlled by varying the thin GaAs capping and InAs regrowth thicknesses [11]. Photoluminescence (PL) of these QDMs show that the peak energies agree well with measured morphology, and temperature variations of the GS and ES peaks can be broadly described by effective onedimensional solutions of coupled Schrödinger-Poisson equations [12].…”

Improved quantum confinement of self-assembled high-density InAs quantum dot molecules in AlGaAs∕GaAs quantum well structures by molecular beam epitaxy

“…The results in Fig. 2͑b͒ show that the PL peak of the one-stack HD-QDM sample is at about 1.2 eV while that of the fivestack sample is redshifted to about 1.19 eV due to the fact that the latter has larger dot sizes which is typical for the multistacking process, 11 and the FWHM of the PL peaks were measured to be 82 and 58 meV for the one-and fivestack HD QDMs, respectively. The smaller FWHM value indicates that the five-stack sample has a greater degree of dot size uniformity than that of the one-stack sample.…”

Manipulation of tunneling induced transparency windows and optical switching features in fivefold quantum dot molecules

“…The dots number of quantum dot molecules grown can be controlled by varying the capping temperature and the capping thickness by thin-capping-and-regrowth molecular beam epitaxy (MBE) process [55]. A quantum dot molecule with four to five dots per molecule can be grown with GaAs capping thickness and InAs regrowth thickness of 25 ML and 1.5 ML respectively [56].…”