Realization of Metal–Insulator Transition and Oxidation in Silver Nanowire Percolating Networks by Terahertz Reflection Spectroscopy

Tsai, Yao-Jiun; Chang, Chi-Ying; Lai, Yi-Chun; Yu, Peichen; Ahn, Hyeyoung

doi:10.1021/am404717j

Cited by 22 publications

(33 citation statements)

References 29 publications

(41 reference statements)

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“…Due to the high effective mass m * = 23m 0 for the La 0.67 Ca 0.33 MnO 3 film, 23 we neglect the cyclotron resonance frequency

= eB/m * . To understand the basic features of the complex conductivities, we employ the Drude–Smith model to analyze the experimental data, 28,29

where the dc conductivity

/m * , n is the carrier density, m * is the carrier effective mass, τ is the relaxation time, and c 1 denotes the fraction of the initial velocity of an electron after scattering events and varies between −1 and 0, which corresponds to localization and Drude formula, respectively. The complex conductivities and the fitted results at 105 K are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Anisotropic terahertz transmission induced by the external magnetic field in La0.67Ca0.33MnO3 film

Mei

Zhang

et al. 2021

Structural Dynamics

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A systemic investigation of the terahertz (THz) transmission of La 0.67 Ca 0.33 MnO 3 film on the (001)-oriented NdGaO 3 substrate under external magnetic field and low temperature have been performed. The significant THz absorption difference between the out-of-plane and the in-plane magnetic field direction is observed, which is consistent with the electrical transport measurement using the standard four-probe technique. Furthermore, we find that the complex THz conductivities can be reproduced in terms of the Drude Smith equation as the magnetic field is perpendicular to the film plane, whereas it deviates from this model when the in-plane magnetic field is applied. We suggest that such anisotropies in THz transport dynamics have close correspondences with the phase separation and anisotropic magnetoresistance effects in the perovskite-structured manganites. Our work demonstrates that the THz time-domain spectroscopy (TDS) can be an effective non-contact method for studying the magneto-transport properties of the perovskite-structured manganites.

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“…Due to the high effective mass m * = 23m 0 for the La 0.67 Ca 0.33 MnO 3 film, 23 we neglect the cyclotron resonance frequency

= eB/m * . To understand the basic features of the complex conductivities, we employ the Drude–Smith model to analyze the experimental data, 28,29

where the dc conductivity

Section: Resultsmentioning

confidence: 99%

Anisotropic terahertz transmission induced by the external magnetic field in La0.67Ca0.33MnO3 film

Mei

Zhang

et al. 2021

Structural Dynamics

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“…[25][26][27][28][29][30] In this work the far-field transmittance spectra of our AgNW network was measured using a conventional THz time-domain spectrometer (THz-TDS), schematically represented in Figure 2a. [25][26][27][28][29][30] In this work the far-field transmittance spectra of our AgNW network was measured using a conventional THz time-domain spectrometer (THz-TDS), schematically represented in Figure 2a.…”

Section: Terahertz Far-field Spectroscopymentioning

confidence: 99%

Terahertz Time‐Domain Spectroscopy and Near‐Field Microscopy of Transparent Silver Nanowire Networks

Hoof

Parente

Baldi

et al. 2019

Advanced Optical Materials

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spin-coating to spray-coating, electrospinning, and dip coating. [3,6,7] Furthermore, large-area lithography and metal coating techniques are increasingly emerging as promising alternatives. [8][9][10] However, it is not uncommon for these deposition techniques to result in a conductance that varies spatially due to local modulations in the network thickness or connectivity. These spatial modulations of the electrical conductance are impossible to detect with standard characterization techniques such as the four-point probe method, in which the electrical impedance is measured using a pair of separated electrodes carrying a current and sensing the voltage differences. Furthermore, although microprobes have been developed to map the conductance with high spatial resolution, [11] the four-point probe technique requires electrical contact with the surface, leading to the risk of modifying the sample. These limitations highlight the need for a contact-free and high resolution technique to map electrical conductance over large areas. Broadband and phase sensitive spectroscopic techniques, such as terahertz time-domain spectroscopy (THz-TDS), have emerged as powerful alternatives for probing the complex conductivity of samples. [12][13][14][15] THz-TDS uses very short (single cycle) electromagnetic pulses as low frequency electromagnetic probes to measure the electronic properties. This probing is done by measuring the attenuation and the phase of the THz pulse as it propagates through the medium and interacts (mainly) with free charge carriers. A major advantage of THz-TDS over four-point probe techniques is that it is a contact free technique, which also enables an easy implementation of conductivity scans. The diffraction limit of electromagnetic waves (on the order of the wavelength) defines the maximum spatial resolution that can be attained for the determination of the conductivity using far-field THz techniques. The broadband character of THz-TDS and the standard focusing optics, with relatively low numerical aperture, leads to spatial resolutions on the order of 1 mm or larger.In this manuscript, we synthesize highly monodisperse AgNWs with a diameter of ≈50 nm and a length of ≈10 μm by adapting a polyol method. [16] Subsequently, transparent electrodes are prepared by spray coating the AgNWs solution on top of 25 × 25 mm 2 quartz substrates. The nanowire monodispersity allows us to draw quantitative conclusions from the measurements performed on the conductive networks. We spatially vary the thickness of the AgNWs network across the quartz substrate, and therefore its optical transmission and THz conductance, by adjusting the spray coating conditions. Transparent conductive layers are key components of optoelectronic devices. Here, a polyol method is used to synthesize large quantities of monodisperse silver nanowires (AgNWs) and these are used to fabricate transparent conducting networks over large areas. The optical extinction and terahertz (THz) conductance of these networks are simultaneously investigated,...

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“…One distinct point of the transverse dynamics for the individual NWs, apart from the longitudinal as well as from the bundled NWs dynamics, is that the excited carriers can be scattered off more easily from the NW surface [29]. While the high probability of carrier backscattering can be understood as the non-Drude conductivity spectrum [2], [30], [31], the electron and hole correlations within transverse region lead to multi-particle Auger scattering, by which the electron and hole are recombined nonradiatively. Consequently, the surface trap-mediated recombination is counterbalanced by this Auger scattering, revealing suppressed decay time constant in the individual SiNWs.…”

Section: Surface Trap Saturation and Auger Recombinationmentioning

confidence: 99%

Counterbalanced Effect of Surface Trap and Auger Recombination on the Transverse Terahertz Carrier Dynamics in Silicon Nanowires

Seo

Kwon

et al. 2015

IEEE Trans. THz Sci. Technol.

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The surface-trap mediated carrier recombination is a crucial feature in characterizing the optoelectronic properties of nanowires (NWs). Due to the one-dimensional characteristics, the photoexcited carriers experiences multiple carrier interactions in the transverse direction such that strong carrier-carrier interactions are expected to play an important role in the NW carrier recombination. Here, using ultrafast optical-pump and terahertzprobe spectroscopy, we show that the Auger scattering significantly reduces the trap-mediated decay process. Systematic studies on bulk Si, bundled, individual, and encapsulated (reduced surfacetrap density) SiNWs reveal that the effect of Auger recombination exhibits strong pump-fluence dependence depending on the surface-treatment condition.Index Terms-Silicon nanowires, terahertz (THz), ultrafast spectroscopy.

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Realization of Metal–Insulator Transition and Oxidation in Silver Nanowire Percolating Networks by Terahertz Reflection Spectroscopy

Cited by 22 publications

References 29 publications

Anisotropic terahertz transmission induced by the external magnetic field in La0.67Ca0.33MnO3 film

Anisotropic terahertz transmission induced by the external magnetic field in La0.67Ca0.33MnO3 film

Terahertz Time‐Domain Spectroscopy and Near‐Field Microscopy of Transparent Silver Nanowire Networks

Counterbalanced Effect of Surface Trap and Auger Recombination on the Transverse Terahertz Carrier Dynamics in Silicon Nanowires

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