Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe<sub>2</sub>

Chen, Xin; Zhang, Saifeng; Wang, Lei; Huang, Yi-Fan; Liu, Huiyan; Huang, Jiawei; Dong, Ningning; Liu, Weimin; Kislyakov, I. M.; Nunzi, Jean‐Michel; Zhang, Long; Wang, Jun

doi:10.1364/prj.7.001416

Cited by 39 publications

(49 citation statements)

References 41 publications

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“…The results of our band gap analysis of bilayer PtSe 2 thin film were consistent with those of other experimental studies 29,41,42 . However, the results for multilayer PtSe 2 thin film differed from those of other reports of semiconducting behavior in films of a similar thickness 29,42,43 . One possibility that could account for these differences is due to different quality of thin films.…”

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confidence: 99%

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Gulo

Yeh

Chang

et al. 2020

Sci Rep

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PtSe2 has received substantial research attention because of its intriguing physical properties and potential practical applications. In this paper, we investigated the optical properties of bilayer and multilayer PtSe2 thin films through spectroscopic ellipsometry over a spectral range of 0.73–6.42 eV and at temperatures between 4.5 and 500 K. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 1000 nm and approached a constant value in the near-infrared frequency range. The thermo-optic coefficients of bilayer and multilayer PtSe2 thin films were (4.31 ± 0.04) × 10−4/K and (–9.20 ± 0.03) × 10−4/K at a wavelength of 1200 nm. Analysis of the optical absorption spectrum at room temperature confirmed that bilayer PtSe2 thin films had an indirect band gap of approximately 0.75 ± 0.01 eV, whereas multilayer PtSe2 thin films exhibited semimetal behavior. The band gap of bilayer PtSe2 thin films increased to 0.83 ± 0.01 eV at 4.5 K because of the suppression of electron–phonon interactions. Furthermore, the frequency shifts of Raman-active Eg and A1g phonon modes of both thin films in the temperature range between 10 and 500 K accorded with the predictions of the anharmonic model. These results provide basic information for the technological development of PtSe2-based optoelectronic and photonic devices at various temperatures.

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confidence: 99%

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Gulo

Yeh

Chang

et al. 2020

Sci Rep

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“…They are characterized by an extracted frequency in the GHz range, which no longer depends on the probe wavelength, but increases when the material gets thinner, as shown in Figure 7 c,d. This has been observed in exfoliated few layer crystals of WSe 2 [ 133 ], MoS 2 [ 143 ], MoSe 2 [ 132 ], InSe [ 135 , 136 , 137 ], PtSe 2 [ 134 ], BP [ 126 ], Bi 2 Se 3 [ 243 ], and Bi 2 Te 3 [ 139 ]. In all these examples, the penetration depth of the pump beam gets larger than the thickness of the sample.…”

Section: Coherent Phonons In Vdw Materialsmentioning

confidence: 80%

Time-Domain Investigations of Coherent Phonons in van der Waals Thin Films

Vialla

Fatti

2020

Nanomaterials

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Coherent phonons can be launched in materials upon localized pulsed optical excitation, and be subsequently followed in time-domain, with a sub-picosecond resolution, using a time-delayed pulsed probe. This technique yields characterization of mechanical, optical, and electronic properties at the nanoscale, and is taken advantage of for investigations in material science, physics, chemistry, and biology. Here we review the use of this experimental method applied to the emerging field of homo- and heterostructures of van der Waals materials. Their unique structure corresponding to non-covalently stacked atomically thin layers allows for the study of original structural configurations, down to one-atom-thin films free of interface defect. The generation and relaxation of coherent optical phonons, as well as propagative and resonant breathing acoustic phonons, are comprehensively discussed. This approach opens new avenues for the in situ characterization of these novel materials, the observation and modulation of exotic phenomena, and advances in the field of acoustics microscopy.

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“…are also confirmed via the thickness-dependent Raman and fluorescence spectra, the temperature-dependent Raman spectra, and the force constants per unit of low frequency modes. [52][53][54][55] For example, the PL spectra of ReX 2 shows negligible layer number dependence. With the thickness of ReS 2 and ReSe 2 thining from bulk to monolayer, their PL intensity decreases along with negligible blueshift of peak position (Figure 2f,g), [13,56] which is consistent well with theoretical bandgap.…”

Section: Optical and Vibration Propertiesmentioning

confidence: 99%

2D Re‐Based Transition Metal Chalcogenides: Progress, Challenges, and Opportunities

Chen

Yang

et al. 2020

Advanced Science

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The rise of 2D transition-metal dichalcogenides (TMDs) materials has enormous implications for the scientific community and beyond. Among TMDs, ReX 2 (X = S, Se) has attracted significant interest regarding its unusual 1T′ structure and extraordinary properties in various fields during the past 7 years. For instance, ReX 2 possesses large bandgaps (ReSe 2 : 1.3 eV, ReS 2 : 1.6 eV), distinctive interlayer decoupling, and strong anisotropic properties, which endow more degree of freedom for constructing novel optoelectronic, logic circuit, and sensor devices. Moreover, facile ion intercalation, abundant active sites, together with stable 1T′ structure enable them great perspective to fabricate high-performance catalysts and advanced energy storage devices. In this review, the structural features, fundamental physicochemical properties, as well as all existing applications of Re-based TMDs materials are comprehensively introduced. Especially, the emerging synthesis strategies are critically analyzed and pay particular attention is paid to its growth mechanism with probing the assembly process of domain architectures. Finally, current challenges and future opportunities regarding the controlled preparation methods, property, and application exploration of Re-based TMDs are discussed.

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Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe₂

Cited by 39 publications

References 41 publications

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Time-Domain Investigations of Coherent Phonons in van der Waals Thin Films

2D Re‐Based Transition Metal Chalcogenides: Progress, Challenges, and Opportunities

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Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe2

Cited by 39 publications

References 41 publications

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Temperature-dependent optical and vibrational properties of PtSe2 thin films

Time-Domain Investigations of Coherent Phonons in van der Waals Thin Films

2D Re‐Based Transition Metal Chalcogenides: Progress, Challenges, and Opportunities

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Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe₂