Papers by Keyword: InAs Quantum dot

Abstract: InAs quantum dots (QDs) have been grown by solid-source molecular beam epitaxy on different InxGa1-xAs (0 ≤ x ≤ 0.3) to investigate the effect of In-mole-fraction and thickness of InGaAs insertion layer (IL) on the structural and optical properties of the QDs. The density of QDs directly grown on GaAs is 1×1010 cm-2, and increase to 1.4-1.8×1010 cm-2 on InGaAs layers which depend on the In-mole-fraction and thickness of InGaAs layers. The effects of In-mole-fraction and thickness of InGaAs insertion layer on optical properties of the QDs are studied by photoluminescence (PL). The FWHM of PL spectrum corresponds to the size distribution of the QDs.

Abstract: The temperature dependence of the photoluminescence (PL) emission spectra of self-organized InAs/GaAs quantum dots (QDs) grown under different growth conditions in the range 20-300K has been investigated. Three InAs QD samples were grown on (100) 2º-tilted toward (111)A Si-doped GaAs substrates by metal-organic chemical vapour epitaxy (MOVPE), with various size uniformities and dot densities. Observing the measured PL spectra at 20K, the differences caused by size uniformities among the three samples were obvious. The PL spectra were simulated with rate equations, taking into account the carrier relaxation between the first excited state and the ground state. Interestingly, the calculated relaxation lifetimes at 20K were 198ps, 139ps and 54ps for the samples. The temperature dependent PL spectra were also simulated using the same model. Based on the calculated values of temperature dependent relaxation lifetimes, the differences in changes with temperature among the three samples are discussed. The results are consistent with the thermal redistribution effect.