Coupled InAs Quantum Dots Research Articles

Carrier relaxation and thermal activation of localized excitons in self-organized InAs multilayers grown on GaAs substrates.

We have investigated the temperature dependence of photoluminescence (PL) properties of a number of self-organized InAs/GaAs heterostructures with InAs layer thickness ranging from 0.5 to 3 ML. The temperature dependence of InAs exciton emission and linewidth was found to display a significant difference when the InAs layer thickness is smaller or larger than the critical thickness around 1.7 ML. The fast redshift of PL energy and an anomalous decrease of linewidth with increasing temperature were observed and attributed to the efficient relaxation process of carriers in multilayer samples, resulting from the spread and penetration of the carrier wave functions in coupled InAs quantum dots. The measured thermal activation energies of different samples demonstrated that the InAs wetting layer may act as a barrier for the thermionic emission of carriers in high-quality InAs multilayers, while in InAs monolayers and submonolayers the carriers are required to overcome the GaAs barrier to escape thermally from the localized states. \textcopyright{} 1996 The American Physical Society.

Formation of Stacked Self-Assembled InAs Quantum Dots in GaAs Matrix for Laser Applications

AbstractVertically coupled InAs quantum dots have been synthesized by MBE through successive deposition of InAs dot sheets and thin GaAs spacers. The energy of ground state transition in PL spectra has been found to depend on a number of dot sheets and the spacer width. Injection laser based on vertically coupled quantum dots demonstrated lasing via the ground state of quantum dots in the entire 80K-300K temperature range. Lower threshold current density and wider range of the thermal stability of threshold current density as compared to the single sheet quantum dot laser have been observed.