Near-Field Magnetophotoluminescence Spectroscopy of Composition Fluctuations in InGaAsN

Mintairov, A. M.; Kosel, T.H.; Merz, J. L.; Blagnov, P. A.; Vlasov, A. S.; Ustinov, V. M.; Cook, R. E.

doi:10.1103/physrevlett.87.277401

Cited by 91 publications

(83 citation statements)

References 25 publications

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“…9,10 For comparison, we first examined the dynamics of the GaN x As 1−x sample by the conventional optical pump-probe method. The system setup was similar to that shown in Fig.…”

mentioning

confidence: 99%

Probing subpicosecond dynamics using pulsed laser combined scanning tunneling microscopy

Takeuchi

Aoyama

Oshima

et al. 2004

Applied Physics Letters

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Time-resolved tunneling current measurement in the subpicosecond range was realized by ultrashort-pulse laser combined scanning tunneling microscopy, using the shaken-pulse-pair method. A low-temperature-grown GaN x As 1−x ͑x = 0.36% ͒ sample exhibited two ultrafast transient processes in the time-resolved tunnel current signal, whose lifetimes were determined to be 0.653± 0.025 and 55. Smaller and faster are the key words in the progress of current nanoscience and technology. Thus, for further advances, a method of exploring the ultrafast transient dynamics of the local quantum functions in organized small structures is eagerly desired. Ultrashort optical pulse technology in the near-infrared to ultraviolet region has allowed us to observe transient phenomena in the femtosecond range, the optical-monocycle region, 1,2 which, however, has a drawback of a relatively low spatial resolution due to electromagnetic wavelength. On the other hand, scanning tunneling microscopy (STM), although its time resolution is limited by circuit bandwidth ͑ϳ100 kHz͒, enables us to observe spatial dynamics at the atomic level in real space. 3 Therefore, the integration of ultrashort optical technology with STM has been one of the most exciting goals since their invention. [4][5][6][7] Pioneering works were performed by Hamers et al., 4-7 which have attracted the extensive interest of researchers in various fields. However, there remain critical problems which have prevented the achievement of the laser-combined STM measurement, such as the displacement current due to the stray capacitance of the tunneling gap and photoelectrons produced by multiple photoabsorption. [4][5][6][7] In such cases, since a large area is included in the processes, the superior space resolution of STM cannot be utilized. In particular, the thermal expansion of the STM tip by photoillumination causes much large noise in the tunneling current, making the measurement difficult.Here, we show the results of the time-resolved tunneling current measurement in the subpicosecond range, which can advance the development of future research in terms of ultimate temporal and spatial resolutions.A schematic of the measurement system is shown in Fig. 1. We adopted the recently developed shaken-pulse-pairexcited STM (SPPX-STM) method, which realizes highly sensitive measurement free from the thermal expansion effect of the tip and sample. 8 The tunneling junction is directly illuminated by a sequence of laser pulse pairs and average tunneling current, I t ͑t d ͒, is measured as a function of the delay time between the two pulses, t d . To decrease broadband noise, the delay time of the two pulses t d is modulated with a small amplitude ⌬t d at frequency , and the tunneling current is detected by a lock-in amplifier. Since the tunneling current I t responds to the modulation as In the pulse-pair-excited STM measurement, the first laser pulse in each pulse pair acts as the pump pulse to excite and modulate the electronic structure of the sample surface, which might cause d...

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“…9,10 For comparison, we first examined the dynamics of the GaN x As 1−x sample by the conventional optical pump-probe method. The system setup was similar to that shown in Fig.…”

mentioning

confidence: 99%

Probing subpicosecond dynamics using pulsed laser combined scanning tunneling microscopy

Takeuchi

Aoyama

Oshima

et al. 2004

Applied Physics Letters

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“…These PL lines can be attributed to recombination of excitons localized within certain spatial regions of the NWs by compositional disorder. Indeed, local fluctuations in [N] may create a threedimensional confinement acting as quantum dots (QD) 29 that are distributed along the NWs. Additionally, the sharp lines can also stem from excitons trapped at stacking faults caused by WZ/ZB polymorphism.…”

mentioning

confidence: 99%

Origin of radiative recombination and manifestations of localization effects in GaAs/GaNAs core/shell nanowires

Chen

Filippov

Ishikawa

et al. 2014

Applied Physics Letters

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Radiative carrier recombination processes in GaAs/GaNAs core/shell nanowires grown by molecular beam epitaxy on a Si substrate are systematically investigated by employing micro-photoluminescence (mu-PL) and mu-PL excitation (mu-PLE) measurements complemented by time-resolved PL spectroscopy. At low temperatures, alloy disorder is found to cause localization of photo-excited carriers leading to predominance of optical transitions from localized excitons (LE). Some of the local fluctuations in N composition are suggested to lead to strongly localized three-dimensional confining potential equivalent to that for quantum dots, based on the observation of sharp and discrete PL lines within the LE contour. The localization effects are found to have minor influence on PL spectra at room temperature due to thermal activation of the localized excitons to extended states. Under these conditions, photo-excited carrier lifetime is found to be governed by non-radiative recombination via surface states which is somewhat suppressed upon N incorporation. (C) 2014 AIP Publishing LLC

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“…This principle was realized nearly three decades ago using nano-apertures (Lewis et al, 1984, Pohl et al, 1984, metallic (Fischer and Pohl ,1989) and dielectric (Coutjon et al 1989, Reddick at al., 1989 nano-tips, allowing nanometer-scale spatial resolution in optical experiments with a wide range of applications including experiments with single semiconductor QDs (Flack et al, 1996, Toda et al, 1996. The high spatial resolution, scanning ability and nondestructive character of the experiment in combination with a high magnetic field and timeresolved techniques, allows the use of NSOM to study structural parameters (Mintairov et al, 2001), the spin structure of exciton states (Ortner et al, 2003, Toda et al, 1998, the temporal coherence of the wave functions (Toda et al, 2000), and the mechanisms of carrier migration (K. Matsuda et al, 2000) and relaxation (Toda et al, 1999) in semiconductor QDs.…”

Section: Optical Spectroscopy Of Quantum Dotsmentioning

confidence: 99%

Molecular States of Electrons: Emission of Single Molecules in Self-Organized InP/GaInP Quantum Dots

Mintairov¹,

Merz²,

Blundell³

2012

Fingerprints in the Optical and Transport Properties of Quantum Dots

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Near-Field Magnetophotoluminescence Spectroscopy of Composition Fluctuations in InGaAsN

Cited by 91 publications

References 25 publications

Probing subpicosecond dynamics using pulsed laser combined scanning tunneling microscopy

Probing subpicosecond dynamics using pulsed laser combined scanning tunneling microscopy

Origin of radiative recombination and manifestations of localization effects in GaAs/GaNAs core/shell nanowires

Molecular States of Electrons: Emission of Single Molecules in Self-Organized InP/GaInP Quantum Dots

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