Nonlinear Optical Properties of Quantum Dots: Excitons in Nanostructures

Fu, Ying; Hellström, Staffan; Ågren, Hans

doi:10.1142/s0218863509004579

Cited by 18 publications

(13 citation statements)

References 86 publications

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“…It should be mentioned that any breakdown mechanism could be different in nanoscale devices. It has, for example, been shown by detailed theoretical analysis that impact ionization can be significantly enhanced in nanostructures compared to bulk-form p-n junctions as a result of increased Coulomb interaction in confined nanostructures [21,22]. The perhaps most plausible explanation is a bias-dependent surface leakage current.…”

Section: Resultsmentioning

confidence: 99%

Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

et al. 2012

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We report on a comprehensive study of electrical and optical properties of efficient near-infrared p⁺-i-n⁺ photodetectors based on large ensembles of self-assembled, vertically aligned i-n⁺ InP nanowires monolithically grown on a common p⁺ InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely ∼100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires.

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Section: Resultsmentioning

confidence: 99%

Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

et al. 2012

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“…Electron energy levels in a QD is characterized by quantized exciton levels: [36][37][38] The valence-band sublevels in an as-grown QD are completely filled and the conduction-band sublevels are completely empty, which is denoted as the vacuum state c 0 ; one electron initially occupying a valence-band sublevel transits to an empty conduction-band sublevel after absorbing a photon, leaving a hole in the valence-band sublevel. The electron and hole interact with each other via Coulombic interaction to form an exciton which is enforced by the spatial confinement of the nano-size QD.…”

Section: Time-resolved Fluorescence Measurementmentioning

confidence: 99%

Mechanisms of fluorescence decays of colloidal CdSe–CdS/ZnS quantum dots unraveled by time-resolved fluorescence measurement

Chmyrov

Widengren

et al. 2015

Phys. Chem. Chem. Phys.

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By narrowing the detection bandpass and increasing the signal-to-noise ratio in measuring the time-resolved fluorescence decay spectrum of colloidal CdSe-CdS/ZnS quantum dots (QDs), we show that directly after the photoexcitation, the fluorescence decay spectrum is characterized by a single exponential decay, which represents the energy relaxation of the photogenerated exciton from its initial high-energy state to the ground exciton state. The fluorescence decay spectrum of long decay time is in the form of β/t(2), where β is the radiative recombination time of the ground-state exciton and t is the decay time. Our findings provide us with a direct and quantitative link between fluorescence decay measurement data and fundamental photophysics of QD exciton, thereby leading to a novel way of applying colloidal QDs to study microscopic, physical and chemical processes in many fields including biomedicine.

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“…Likewise, the intersubband optical transitions in MLQD are presented by several authors. [18][19][20][21][22][23][24][25][26][27][28] Recently, Suseel Rahul et al 29 report on the absorption characteristics of MLQD within the framework of e®ective mass approximation. Their studies show that the absorption characteristics can be¯nely tuned by varying the layer thicknesses.…”

Section: Introductionmentioning

confidence: 99%

Size-dependent electronic and optical properties in zinc-blende InGaN/GaN multilayer spherical quantum dot

Ortakaya

Kirak

Güldeste

2017

J. Nonlinear Optic. Phys. Mat.

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A theoretical investigation of the binding energy, the radial probability distribution and optical properties (absorption coe±cient (AC) and refractive index change (RIC)) of InGaN/GaN multilayer quantum dot (QD) is presented. The calculations are performed within the e®ective-mass approximation. A shooting method is presented to obtain numerical values for the eigenvalues and eigenfunctions of the structure. The energy eigenvalue, density of probability and optical absorption are compared for cases without and with impurity. It is also found that the ACs and RICs exhibit blue or redshift with di®erent structure of potential pro¯le. The results indicate that the optical properties can be sensitively adjusted by geometry of structure and the presence of impurity.

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Nonlinear Optical Properties of Quantum Dots: Excitons in Nanostructures

Cited by 18 publications

References 86 publications

Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

Mechanisms of fluorescence decays of colloidal CdSe–CdS/ZnS quantum dots unraveled by time-resolved fluorescence measurement

Size-dependent electronic and optical properties in zinc-blende InGaN/GaN multilayer spherical quantum dot

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Nonlinear Optical Properties of Quantum Dots: Excitons in Nanostructures

Cited by 18 publications

References 86 publications

Electrical and optical properties of InP nanowire ensemble p+–i–n+photodetectors

Electrical and optical properties of InP nanowire ensemble p+–i–n+photodetectors

Mechanisms of fluorescence decays of colloidal CdSe–CdS/ZnS quantum dots unraveled by time-resolved fluorescence measurement

Size-dependent electronic and optical properties in zinc-blende InGaN/GaN multilayer spherical quantum dot

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Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors