Tuning the dynamic properties of electrons between a quantum well and quantum dots

Abstract

We present a study of the dynamic properties of electrons tunneling from an InGaAs quantum well to self assembled InAs quantum dots. The experiments were conducted on three highly asymmetric quantum dot infrared photodetectors, where the quantum well and quantum dots were separated by a composite GaAs/AlGaAs/GaAs barrier, which varied from 3.5 nm to 7.0 nm. We performed interband (photoluminescence) and intraband (photocurrent) measurements to characterize the spectral properties of the well and the dots. The photoluminescence measurements revealed that the two nanostructures are decoupled when the device is at zero bias. By intraband pump-probe experiments and photocurrent saturation experiments, we were able to extrapolate a refilling time τ from the well to the dots, which varied from a few μs for the thinnest barrier and hundreds of μs for the thickest one. The extracted values are in good agreement with characteristic tunneling times computed by using a model based on the theoretically predicted transmission coefficient of the electrons through the composite barrier.

Control of Dynamic Properties of InAs/InAlGaAs/InP Hybrid Quantum Well‐Quantum Dot Structures Designed as Active Parts of 1.55 μm Emitting Lasers

“…Hybrid systems, combining 3D quantum confinement of quantum dots (QDs), separated by a thin barrier from 1D potential of a quantum well (QW), constitute interesting objects of study from the fundamental point of view, as a laboratory for investigating coupling between carriers of different dimensionality; and from the application point of view, since they can be used as an active material for telecom lasers with high speed modulation, QD‐based memory devices, infrared photodetectors or quantum‐dot‐based quantum cascade lasers . When used in lasers, they alleviate the typical problems with QD systems, i.e., high population of hot carriers occupying excited states in the dots and even wetting layer (WL) or barrier states, which limits their modulation speed; and low total volume of QDs, hence low capture rate of carriers.…”

Complementary split-ring resonator antenna coupled quantum dot infrared photodetector

“…where N QD is the electron sheet density in the QD layer; the quantities G ref and G CSRR are coefficients quantifying the optical coupling between the incident radiation and the QDIP active region; r ip and r z are the values of the crosssections associated to the photogeneration process, 22 for light polarized along the in-plane (ip) and growth (z) directions. For this type of QDIP, we estimated experimentally a ratio r z /r ip ' 4.5.…”

Infrared transmission spectroscopy of charge carriers in self-assembled InAs quantum dots under surface electric fields

“…Quantum-confined zero-dimensional semiconductor quantum dots (QDs) have attracted an unparallel interest over more than a decade [1,2]. These nanostructures have an immense potential for device applications ranging from simple electronic memories [3] to novel optoelectronics [4].…”

“…The novelty can be extended by combining a quantum well (QW) with these zero-dimensional systems. Tunneling dynamics (refilling times) of electrons from QW to QD are tunable from µs to ms by changing the barrier thickness between them [1,5].…”