Disorder-induced photoluminescence up-conversion in InAs/GaAs quantum-dot samples

Abstract

Photoluminescence up-conversion under cw excitation in semiconductor quantum-dot structures is systematically studied in a sample exhibiting a crossover between two-dimensional and three-dimensional (3D) growth modes. We probe the existence of carrier up-conversion by using ultrathin quantum wells close to the quantum-dot layer. We show that the efficiency of the up-conversion is closely related to the disorder induced by the 3D-growth mode of the quantum dots.

Temperature-Dependent Photoluminescence of Self-Assembled (In,Ga)As Quantum Dots on GaAs (100): Carrier Redistribution through Low-Energy Continuous States

“…2(b)]. As has been discussed in previous reports, [6][7][8] this absorption tail is attributed to the continuous states between the WL and QDs. 500 nm 14 nm Fig.…”

“…2(b)]. [6][7][8] The integrated PL intensity is constant or rather increases in this temperature range, indicating the absence of nonradiative recombination centers in the channels and a higher PL efficiency (longer radiative lifetime 23) ) of the low-energy QDs preferentially occupied during the carrier redistribution. The detailed analysis of the temperature-dependent PL peak position and width in this temperature range provides important insight into the properties of these channels.…”

“…Photoluminescence excitation (PLE) measurements of single QDs have demonstrated the existence of background absorption due to a density of continuous states that increases gradually between the QD ground-state and the WL states. [6][7][8] It has been suggested that these continuous states originate from structural imperfections that cause a crossover between the 0D-QD and 2D-WL character or band-tail states of the WL. [6][7][8] The continuous states have been theoretically attributed recently to the intrinsic crossing of the free-tobound and bound-to-free QD and WL transitions.…”

“…[6][7][8] It has been suggested that these continuous states originate from structural imperfections that cause a crossover between the 0D-QD and 2D-WL character or band-tail states of the WL. [6][7][8] The continuous states have been theoretically attributed recently to the intrinsic crossing of the free-tobound and bound-to-free QD and WL transitions. 9) In this paper we provide insight into the nature of the continuous states by temperature-dependent photoluminescence (PL) measurements of an ensemble of QDs.…”

Photoneutralization and slow capture of carriers in quantum dots probed by resonant excitation spectroscopy

“…Let us now discuss the power dependence introduced for γ 1 and γ 2 . Considering the evolution of the barrier electron (hole) population N e (N h ) under a non-resonant excitation [37] and the fact that the photoluminescence of the GaAs barrier is not influenced by the QDs population [38], the populations N e and N h created by the optical gate are governed by bimolecular interband radiative recombination [13,37] and are proportional to √ P gate . The carriers can be then captured in the QD and the defect in its vicinity, either by the emission of optical phonons, or by Auger processes.…”