Charge transport in thin layer NaxCoO2(x∼ 0.63) studied by terahertz spectroscopy

Němec, H.; Knı́žek, K.; Jirák, Z.; Hejtmánek, J.; Soroka, Miroslav; Buršík, J.

doi:10.1088/0953-8984/28/35/355601

Cited by 3 publications

(1 citation statement)

References 39 publications

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“…The investigated systems include silicon nanocrystals, [80,140] CdS nanocrystals, [141] various nanostructures of TiO 2 , [63,79,[142][143][144] ZnO nanoparticles, [145,146] InP nanowires, [67] Sb-doped SnO 2 nanoparticles [3,26] or nanogranular Na 0.63 CoO 2 films. [147] These studies mostly take advantage of the combination of experimental results with calculations based on microscopic parameters and on the morphology of investigated systems and yield essentially the intrinsic mobility of carriers inside nanoparticles, the length scale of the spatial confinement of carriers and the probability of inter-nanoparticle transport. In ref.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Kužel

Němec

2019

Advanced Optical Materials

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Transport of charges is a fundamental process in many high-tech applications including photovoltaic or optoelectronic devices, but also in more ordinary components such as unsophisticated wires and other circuitry. The development of nanotechnologies resulted in the fabrication of highly complex materials consisting of a large variety of nanosized elements, which inevitably involve a multitude of charge transport processes occurring on various time-and length-scales. Figure 1 summarizes the most common nanoelements with high application potential.For example, the electrodes employed in Grätzel solar cells [1] are composed of percolated networks of a huge number of metal oxide nanoparticles (top-left panel in Figure 1). Colloidal nanocrystals form the basis for thin film electronics and flexible electronic devices. [2] The synthetic approaches control their composition, size and electronic structure (energy levels, density of states within the bands and in the bandgap) and the charge-carrier transport. [2,3] Nanowires and nanotubes made of conventional semiconductors are quasi 1D systems combining Terahertz spectroscopy has been used for almost two decades for investigations of nanomaterials, including nanocrystals, nanoparticles, nanowires, nanotubes or 2D crystals. Its great importance stems from the fact that it is a noncontact method and, owing to its high frequency and broadband character, it is capable of characterizing charge transport properties within individual nano-objects but also among them. In addition, probing of photoinitiated ultrafast charge dynamics is possible thanks to the sub-picosecond time resolution. Despite this unprecedented potential, the interpretation of the measured terahertz conductivity spectra in many materials is still intensively debated. Herein is presented a review of the experiments performed on nanostructures of conventional semiconductors and on carbon nanomaterials (graphene and carbon nanotubes) during the past decade. The state of the art of the theoretical formalism is provided and discussed, including the intrinsic response, as well as the role of inherent heterogeneity and of the experimental conditions.

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Section: Wwwadvopticalmatdementioning

confidence: 99%

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Kužel

Němec

2019

Advanced Optical Materials

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Dielectric and conducting properties of unintentionally and Sn-doped β-Ga2O3 studied by terahertz spectroscopy

Blumenschein

Kadlec

Romanyuk

et al. 2020

Journal of Applied Physics

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Dielectric and conducting properties of unintentionally doped bulk and Sn-doped thin film β-Ga2O3 samples were studied using time-domain terahertz spectroscopy. Complex permittivity and optical conductivity spectra from 0.25 to 2.5 THz were obtained experimentally over a broad temperature range. The low-temperature spectra of the unintentionally doped sample were fit using a model involving two oscillators. The parameters of one of them show an unusual temperature dependence, in particular, a pronounced increase in the oscillator strength upon heating above 50 K. This is interpreted as an absorption due to thermally activated charge carriers moving in localized potential minima linked to the unintentional doping. Upon heating, the influence of this optical conductivity mechanism strongly increases, and the sample becomes opaque in the THz range near 100 K. The nanocrystalline Sn-doped Ga2O3 thin film sample exhibits a much higher optical conductivity than the unintentionally doped bulk sample, and its spectra are remarkably stable over a broad temperature range (4–750 K). This first study of β-Ga2O3 based on phase-sensitive THz spectroscopy reveals how the impurities influence the high-frequency conductive properties of the material.

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Metal-insulator transition in (Pr,Y)0.7Ca0.3CoO3 in the far-infra

et al. 2020

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Charge transport in thin layer Na_xCoO₂(x∼ 0.63) studied by terahertz spectroscopy

Cited by 3 publications

References 39 publications

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Dielectric and conducting properties of unintentionally and Sn-doped β-Ga2O3 studied by terahertz spectroscopy

Metal-insulator transition in (Pr,Y)0.7Ca0.3CoO3 in the far-infra

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