Fluorescence Intermittency in Self-Assembled InP Quantum Dots

Sugisaki, Mitsuru; Ren, Hongwen; Nishi, Kenichi; Masumoto, Yasuaki

doi:10.1103/physrevlett.86.4883

Cited by 73 publications

(64 citation statements)

References 20 publications

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“…This phenomenon is referred to as fluorescence (photoluminescence) PL intermittency and blinking are observed frequently in single dye molecules 13,19 and single semiconductor quantum dots. 14,20,21 Several mechanisms have been proposed to explain these phenomena, 13,14,[19][20][21] because the time scale of the PL intermittency and on-off blinking phenomena depend on the system and experimental conditions. As a possible mechanism, the reorientation of a molecule (direction of the dipole moment) could cause the PL intensity fluctuation; however, the SWNTs with 100-300 nm length are fixed on the substrate surface by strong van der Waals interactions.…”

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confidence: 99%

“…This phenomenon is referred to as fluorescence (photoluminescence) intermittency, in which the PL intensity switches multiple levels as time passes. [19][20][21] Thermal heating by the excitation laser was ruled out as the origin of this PL intensity fluctuation, because we acquire the data at lower excitation power. Furthermore, if thermal heating caused the PL intensity fluctuation, the PL intensity fluctuation should be observed in all SWNTs.…”

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confidence: 99%

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Photoluminescence intermittency in an individual single-walled carbon nanotube at room temperature

Matsuda

Kanemitsu

Irie

et al. 2005

Applied Physics Letters

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We described the photoluminescence (PL) properties of individual micelle-encapsulated single-walled carbon nanotubes (SWNTs) at room temperature. Single PL peaks from isolated individual SWNTs with a chiral index of (6, 5) showed a linear increase and saturation behavior of the PL intensity. Unusual PL intensity fluctuation in the temporal evolutions of the PL intensity, referred to as PL intermittency, was seen with some SWNTs, while the PL intensity with most SWNTs remained at a constant amplitude. The mechanism of the PL intermittency was discussed.a) Also at Kanagawa Academy of Science and Technology, Takatsu, Japan b) Also at Nanostructure and Material Property, PRESTO, Japan Science and Technology Agency, SWNTs suspended between pillars above a silicon substrate 6,7 when the SWNTs were prevented from becoming bundled or contacting the substrate. PL spectroscopy has revealed new insights into the optical and electronic properties of SWNTs. [4][5][6][7][8][9] Bachilo et al.demonstrated that the chirality of SWNTs can be determined from the energy positions in the PL spectra and PL excitation spectra. 5 However, SWNTs are an inhomogeneous system because the optical transition energy differs from a SWNT to a SWNT, even for those with the same chirality. 10,11 As a result, the macroscopic PL spectrum reflects the ensemble average of signals from many SWNTs and is inhomogeneously broadened. This makes it difficult to investigate the intrinsic optical properties of a SWNT, such as the homogeneous linewidth or variation in the PL intensity from a SWNT to a SWNT. Spectroscopic observation of an individual SWNT, called individual SWNT spectroscopy, is useful for understanding the physics of the inhomogeneous system, 10-12 as with the spectroscopy of fluorescent dye molecules 13 and semiconductor quantum dots. 14 Single molecule spectroscopy enabled us to reveal the intrinsic homogeneous linewidth and unusual phenomena, such as fluorescence (photoluminescence) blinking or intermittency, 13 in which the emission peak and intensity fluctuate over time.In this letter, we report on the PL spectrum and time traces of the PL intensity of individual micelle-encapsulated SWNTs at room temperature. We found clear differences in the time traces from a SWNT to a SWNT, i.e. most SWNTs showed stable emissions, although PL intermittency behavior was seen in specific SWNTs. The room temperature emission properties of an individual SWNT will provide us with important information for fabricating optical devices at the single SWNT level. 15 A zeolite-supported metal catalyst was prepared using a reported procedure. 16,17 Cobalt acetate and iron acetate were impregnated into USY-zeolite powders. The amounts of Co and Fe were 2.5 wt % each, with respect to the zeolite powder. The details of the ACCVD procedure have been reported. 17 The catalysts were placed in a quartz boat, which was set in a quartz tube inside an electric furnace. While heating of the electric furnace, Ar/H 2 (3 % H 2 ) was supplied at 300 sccm to mainta...

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confidence: 99%

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confidence: 99%

Photoluminescence intermittency in an individual single-walled carbon nanotube at room temperature

Matsuda

Kanemitsu

Irie

et al. 2005

Applied Physics Letters

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“…This phenomenon was explained in terms of an IR laser induced release of carriers, which were trapped into deep defects from the QD's. The considerable changes in the fluctuations of the I QD during the time interval of the measurement were detected, when the sample was illuminated with an additional near-IR laser irradiation [24]. Carriers trapped at deep localized centers in the vicinity of the QDs were suggested to be responsible for the observed phenomenon [24].…”

Section: Introductionmentioning

confidence: 94%

“…To the best of our knowledge, there are very few earlier publications [23,24] devoted to studies of IR laser induced changes in I QD . In contrast to our findings, it was found [23] that the IR laser induces an increase of the PL from the QD's by up to 40%.…”

Section: Introductionmentioning

confidence: 99%

Effect of an Electric Field on the Carrier Collection Efficiency of InAs Quantum Dots

et al. 2005

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Individual and multi quantum dots of InAs are studied by means of microphotoluminescence in case when, in addition to the principal laser exciting photoluminescence, second infrared laser is used. It is demonstrated that the absorption of the infrared photons effectively creates free holes in the sample, which leads to both change in the charge state of a quantum dot and to the considerable reduction of their photoluminescence signal. The later effect is explained in terms of an effective screening of the internal electric field, facilitating the carrier transport along the plane of a wetting layer, by the surplus holes from the infrared laser. It is shown that the effect of quenching of quantum dot photoluminescence gradually disappears at increased sample temperature (T ) and / or dot density. This fact is due to the essentially increased value of quantum dot collection efficiency which could be achieved at elevated sample temperatures for the individual quantum dots or even at low T for the case of multi quantum dots. It is suggested that the observed phenomena can be widely used in practice to effectively manipulate the collection efficiency and the charge state of quantum dot-based optical devices.

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“…All these expectations make QDs very attractive and promising candidates for electro-optic devices. Motivated by these expectations, several research groups have extensively studied the optical properties of QDs, and various kinds of important and interesting findings have been successfully reported, 1,2 such as many carrier effects in external fields, [3][4][5][6] strong optical anisotropy, 7-10 fluorescence intermittency, [11][12][13] and Rabi oscillations. [14][15][16][17][18][19] In these investigations, the observation of single QDs is a key: single dot spectroscopy is one of the most promising techniques to reveal the nature of QDs hidden behind the ensemble because exciton parameters can be directly obtained.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic optical response of InP self-assembled quantum dots studied by pump-probe spectroscopy

et al. 2007

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Transient anisotropic reflectivity change spectra of InP quantum dots have been observed by means of two-color pump-probe spectroscopy. The results show a fast decay component with a lifetime of 100-200 ps which depends on the probe energy, followed by the slow decay component of ϳ1 ns. The reflectivity change spectra have a dispersive shape having a maximum on the higher energy side of the photoluminescence ͑PL͒ band by 80 meV, and a dip located at the maximum of the PL band. Interestingly, the reflectivity change signals observed for the ͓110͔ and ͓110͔ polarizations have the opposite sign when the probe energy is set between the first and second exciton states. The temporal change of spectra is simulated by means of a Monte Carlo method, and the model is found to well reproduce the experimental result. Further, the model enables us to evaluate the microscopic exciton parameters of single quantum dots by macroscopic observations. The oscillator strengths along the ͓110͔ and ͓110͔ directions at the PL peak energy are evaluated to be f x = 0.37 and f y = 0.71, respectively. The oscillator strength is about five times smaller than simple theoretical estimates. This suggests a small overlap of the envelope functions which is consistent with the existence of a permanent dipole moment observed in these QDs.

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Fluorescence Intermittency in Self-Assembled InP Quantum Dots

Cited by 73 publications

References 20 publications

Photoluminescence intermittency in an individual single-walled carbon nanotube at room temperature

Photoluminescence intermittency in an individual single-walled carbon nanotube at room temperature

Effect of an Electric Field on the Carrier Collection Efficiency of InAs Quantum Dots

Anisotropic optical response of InP self-assembled quantum dots studied by pump-probe spectroscopy

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