Bases for time-resolved probing of transient carrier dynamics by optical pump–probe scanning tunneling microscopy

Yokota, Munenori; Yoshida, Shoji; Mera, Yutaka; Takeuchi, Osamu; Oigawa, Haruhiro; Shigekawa, Hidemi

doi:10.1039/c3nr02433d

Cited by 11 publications

(6 citation statements)

References 38 publications

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“…The surface-side decay time is generally longer than the bulkside decay time because counterpart carriers are absent near the surface due to the depletion layer, and holes near the surface need to move into the bulk to combine with electrons. Thus, the two decay times obtained by fitting correspond to the decay ( ∼ 5 ns) and the surface-side decay ( ∼ 120 ns), and are consistent with previous results 41 .…”

Section: Resultssupporting

confidence: 91%

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Externally-triggerable optical pump-probe scanning tunneling microscopy with a time resolution of tens-picosecond

Iwaya¹,

Yokota²,

Hanada³

et al. 2023

Sci Rep

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Photoinduced carrier dynamics of nanostructures play a crucial role in developing novel functionalities in advanced materials. Optical pump-probe scanning tunneling microscopy (OPP-STM) represents distinctive capabilities of real-space imaging of such carrier dynamics with nanoscale spatial resolution. However, combining the advanced technology of ultrafast pulsed lasers with STM for stable time-resolved measurements has remained challenging. The recent OPP-STM system, whose laser-pulse timing is electrically controlled by external triggers, has significantly simplified this combination but limited its application due to nanosecond temporal resolution. Here we report an externally-triggerable OPP-STM system with a temporal resolution in the tens-picosecond range. We also realize the stable laser illumination of the tip-sample junction by placing a position-movable aspheric lens driven by piezo actuators directly on the STM stage and by employing an optical beam stabilization system. We demonstrate the OPP-STM measurements on GaAs(110) surfaces, observing carrier dynamics with a decay time of $$\sim 170$$ ∼ 170 ps and revealing local carrier dynamics at features including a step edge and a nanoscale defect. The stable OPP-STM measurements with the tens-picosecond resolution by the electrical control of laser pulses highlight the potential capabilities of this system for investigating nanoscale carrier dynamics of a wide range of functional materials.

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Section: Resultssupporting

confidence: 91%

“…6 need to move into the bulk to combine with electrons. Thus, the two decay times obtained by fitting correspond to the bulk-side decay (∼ 5 ns) and the surface-side decay (∼ 120 ns), and are consistent with previous results [41].…”

Section: Resultssupporting

confidence: 91%

Externally-triggerable optical pump-probe scanning tunneling microscopy with a time resolution of tens-picosecond

Iwaya¹,

Yokota²,

Hanada³

et al. 2023

Sci Rep

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“…In addition, since an ultrafast pulse picker used in our system, integrated with an RTP crystal (LEYSOP, RTP-3-20) operating at 1 MHz, generally has a limited extinction ratio of 250:1, 17) some of the light other than the selected (picked) and transmitted light also passes through, which has an adverse effect on the measurement of some object. 18) With the above perspective, here we present a newly developed OPP-STM system that utilizes externally triggerable pulse lasers, which we call externally triggerable OPP-STM (ET-OPP-STM). Figure 1 shows a schematic illustration of the designed system.…”

mentioning

confidence: 99%

Externally triggerable optical pump-probe scanning tunneling microscopy

Mogi

Wang

Kikuchi

et al. 2019

Appl. Phys. Express

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Optical pump-probe scanning tunneling microscopy (OPP-STM) has enabled the measurement of ultrafast dynamics in real space. However, the use of a pulse picker to extract selected laser pulses to realize delay-time modulation, which efficiently suppresses the thermal expansion problems, limits the availability of time-resolved measurement. Here, we present a more applicable type of OPP-STM that we have developed. Two externally triggerable pulse lasers were used to produce pump and probe pulses, and wide-range delay-time modulation was simply realized by adjusting the timing of the pulses. The performance of this new type of OPP-STM was demonstrated by measuring the carrier dynamics in WSe2.

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“…7,8 However, the quantum resonant tunneling effect (QRT) is difficult to observe for these abovementioned systems. For studying QRT, the quantum dot is often called an "artificial atom" and the performance concerning the electron transport has to be implemented in a microcosmic and low temperature condition, [9][10][11] which is not convenient for experimental operations. For the purpose of manipulation, it is important to design a special system in which quantum electronic transport can be observed at around room temperature.…”

Section: Introductionmentioning

confidence: 99%

Room-temperature resonant quantum tunneling transport of macroscopic systems

et al. 2014

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A self-assembled quantum dots array (QDA) is a low dimensional electron system applied to various quantum devices. This QDA, if embedded in a single crystal matrix, could be advantageous for quantum information science and technology. However, the quantum tunneling effect has been difficult to observe around room temperature thus far, because it occurs in a microcosmic and low temperature condition. Herein, we show a designed a quasi-periodic Ni QDA embedded in a single crystal BaTiO3 matrix and demonstrate novel quantum resonant tunneling transport properties around room-temperature according to theoretical calculation and experiments. The quantum tunneling process could be effectively modulated by changing the Ni QDA concentration. The major reason was that an applied weak electric field (∼10(2) V cm(-1)) could be enhanced by three orders of magnitude (∼10(5) V cm(-1)) between the Ni QDA because of the higher permittivity of BaTiO3 and the 'hot spots' of the Ni QDA. Compared with the pure BaTiO3 films, the samples with embedded Ni QDA displayed a stepped conductivity and temperature (σ-T curves) construction.

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Bases for time-resolved probing of transient carrier dynamics by optical pump–probe scanning tunneling microscopy

Cited by 11 publications

References 38 publications

Externally-triggerable optical pump-probe scanning tunneling microscopy with a time resolution of tens-picosecond

Externally-triggerable optical pump-probe scanning tunneling microscopy with a time resolution of tens-picosecond

Externally triggerable optical pump-probe scanning tunneling microscopy

Room-temperature resonant quantum tunneling transport of macroscopic systems

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