Quantum dots for terahertz generation

Liu, H C; Aslan, B.; Gupta, J. A.; Wasilewski, Z. R.; Aers, G. C.; SpringThorpe, A. J.; Buchanan, M.

doi:10.1088/0953-8984/20/38/384211

Cited by 5 publications

(4 citation statements)

References 9 publications

(11 reference statements)

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“…17,18 However, in recent times, the material need for producing and detecting terahertz are becoming abundant and consequently work on the that spectroscopy is also booming. For example, nanostructures 19,20 such as quantum dots and dendrimers 21,22 have been used for the generation and detection of terahertz radiation. These nanostructures are significantly smaller in size than conventional sources of terahertz radiation and thus make terahertz devices compact and relatively low cost.…”

Section: Introductionmentioning

confidence: 99%

Terahertz spectroscopic studies of quantum dots–conjugated gold nanoparticles

Uddin¹,

Ghann²

2018

MSEIJ

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Composite structures of metal nanoparticles and semiconductor nanomaterials present unique properties that have made them candidates for various applications. The properties of these hybrid structures to a large extent depend on the design and specific material used in to produce them. Here, we present work on the synthesis and characterization of CdSeS/ZnS quantum-dot-gold nanoparticles hybrids (denoted as QD-GNP) and studies on their interaction with terahertz radiation. The prepared QD-GNPs were characterized using UV-vis spectroscopy (UV-vis), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Fluorescence Spectrometry, and Photoluminescence Lifetime measurement. The wavelength of maximum absorption of the gold nanoparticles was 519 nm while that of the quantum dot was 609 nm. The peak absorption band of the hybrid solution was around 519 nm. Transmission electron microscopy imaging revealed the surface morphological features of the quantum dot and gold nanoparticle. Strong photoluminescence quenching was observed upon the conjugation of the quantum dots with gold nanoparticles. The observed difference in the lifetime of free quantum dot and the hybrid QD-GNP was an indication of the bonding between the quantum dot and gold nanoparticles. A biexponential decay was observed with a lifetime of 3.57 ns for bare quantum dots and 1.05 ns for QD-GNP as for the faster component and the slower component 15.09 ns and 8.30 ns QD AND QD-GNP, respectively. Unique features were observed on the terahertz spectra of the composite structures in comparison with that of the either the QD or the GNP.

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Section: Introductionmentioning

confidence: 99%

Terahertz spectroscopic studies of quantum dots–conjugated gold nanoparticles

Uddin¹,

Ghann²

2018

MSEIJ

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“…For example, InAs QDs fabricated on the GaAs(001) substrate by MBE may be used in mid-and far-infrared detectors (see, for example, Refs. [2,3]), terahertz emitters [4,5], vertical-external-cavity surface-emitting lasers (see review article, Ref. [6]), and single-photon emitters (see review article, Ref.…”

Section: Introductionmentioning

confidence: 99%

Self-assembly of InAs quantum dots on GaAs(001) by molecular beam epitaxy

Jin

2015

Front. Phys.

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Currently, the nature of self-assembly of three-dimensional epitaxial islands or quantum dots (QDs) in a lattice-mismatched heteroepitaxial growth system, such as InAs/GaAs(001) and Ge/Si(001) as fabricated by molecular beam epitaxy (MBE), is still puzzling. The purpose of this article is to discuss how the self-assembly of InAs QDs in MBE InAs/GaAs(001) should be properly understood in atomic scale. First, the conventional kinetic theories that have traditionally been used to interpret QD self-assembly in heteroepitaxial growth with a significant lattice mismatch are reviewed briefly by examining the literature of the past two decades. Second, based on their own experimental data, the authors point out that InAs QD self-assembly can proceed in distinctly different kinetic ways depending on the growth conditions and so cannot be framed within a universal kinetic theory, and, furthermore, that the process may be transient, or the time required for a QD to grow to maturity may be significantly short, which is obviously inconsistent with conventional kinetic theories. Third, the authors point out that, in all of these conventional theories, two well-established experimental observations have been overlooked: i) A large number of “floating” indium atoms are present on the growing surface in MBE InAs/GaAs(001); ii) an elastically strained InAs film on the GaAs(001) substrate should be mechanically unstable. These two well-established experimental facts may be highly relevant and should be taken into account in interpreting InAs QD formation. Finally, the authors speculate that the formation of an InAs QD is more likely to be a collective event involving a large number of both indium and arsenic atoms simultaneously or, alternatively, a morphological/structural transformation in which a single atomic InAs sheet is transformed into a three-dimensional InAs island, accompanied by the rehybridization from the sp 2-bonded to sp 3-bonded atomic configuration of both indium and arsenic elements in the heteroepitaxial growth system.

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“…Impurity related electronic and optical properties of quantum wells have attracted a lot of interest in recent years 1–6 due to their potential THz applications. The presence of impurities in a quantum well brings on localized states below the edge of the first subband in the quantum well 7, 8.…”

Section: Introductionmentioning

confidence: 99%

Effects of magnetic field on the terahertz nonlinear optical properties in donor‐doped GaAs/AlGaAs quantum wells

Yıldırım

Aslan

2012

Physica Status Solidi (b)

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Effects of the magnetic field on nonlinear optical properties at THz range in GaAs/AlGaAs quantum wells doped with donor atoms are investigated. Expressions for the third‐order nonlinear optical susceptibilities are obtained through the solution of the density matrix equations of motion within the rotating wave approximation. Donor binding energies are calculated variationally by means of an iterative shooting algorithm. Magnetic field has strong effect on the nonlinear susceptibility: it removes the degeneracy in energies of 2p± impurity states and increases the absolute value of the nonlinearity. It is also shown that a large and tunable optical nonlinear figure of merit is possible with the magnetic field applied in the growth direction. The nonlinear optical quantities are also calculated for donor distributions with different full width at half maximum values in the absence of magnetic field and the observed features at low energy part are attributed to the increasing homogeneity in the donor distribution.

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Quantum dots for terahertz generation

Cited by 5 publications

References 9 publications

Terahertz spectroscopic studies of quantum dots–conjugated gold nanoparticles

Terahertz spectroscopic studies of quantum dots–conjugated gold nanoparticles

Self-assembly of InAs quantum dots on GaAs(001) by molecular beam epitaxy

Effects of magnetic field on the terahertz nonlinear optical properties in donor‐doped GaAs/AlGaAs quantum wells

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