Thickness-Dependent Ultrafast Photocarrier Dynamics in Selenizing Platinum Thin Films

Fu, Jibo; Xu, Wenqi; Chen, Xin; Zhang, Saifeng; Zhang, Wenjie; Suo, Peng; Lin, Xian; Wang, Jun; Jin, Zuanming; Liu, Weimin; Ma, Guohong

doi:10.1021/acs.jpcc.0c01509

Cited by 27 publications

(34 citation statements)

References 51 publications

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“…film changes from semiconductor into semimetal with the increasing thickness. [24][25] The band gap of our 5-layer PtSe2 is determined to be about 0.52 eV from the UV-visible absorption spectra, which is accord to the previous report. 24 Both G1 and G2 show similar absorption and identical bandgap.…”

Section: Methodssupporting

confidence: 91%

“…[24][25] The band gap of our 5-layer PtSe2 is determined to be about 0.52 eV from the UV-visible absorption spectra, which is accord to the previous report. 24 Both G1 and G2 show similar absorption and identical bandgap. 25 A typical Raman spectrum obtained from two heterojunctions are demonstrated in Fig.…”

Section: Methodssupporting

confidence: 91%

“…1(c) shows two pronounced peaks in 175 cm -1 and 204 cm -1 . The peaks in the two films can be ascribed to in-plane vibration (175 cm -1 , Eg mode) and out of plane vibration (204 cm -1 , A1g mode) of the Pt and Se atoms, 24 respectively. The intensity rations of A1g and Eg is about 0.16 that is nearly same as previous report.…”

Section: Methodsmentioning

confidence: 99%

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Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Ma¹,

Zhang²,

Wang³

et al. 2021

Preprint

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Van der Waals heterojunction involving graphene (Gr) with transition metal dichalcogenides (TMDs) is regard as a promising structure for their outstanding performance in optical and optoelectronic response. The electron-hole thermalization has been deemed to be the main reason for the sub-bandgap-excitation charge transfer from Gr to TMDs. However, the role of the intricate interlayer interaction of the Gr and the TMDs still require intensive investigation. Here, we have investigated the photocarrier dynamics in 5-layer PtSe2/Gr heterojunction by using time-resolved optical pump and terahertz probe spectroscopy. Interestingly, after photoexcitation, electron transfer from PtSe2 to Gr in PtSe2/Gr/substrate heterojunction has been demonstrated successfully, by contrast, no observable charge transfer occurs in the Gr/PtSe2/substrate heterostructure. The prominent difference for the different stacking sequence between Gr and PtSe2 can be ascribed to the effective built-in field introduced by fused silica substrate. A physical picture accounting for built-in electric field introduced by substrate has been proposed to interpret the charge transfer process in the TMD/Gr heterostructure–the substrate built-in electric field plays a dominated role for controlling the charge transfer pathway in the TMDs/Gr heterojunction. This study not only shed the light to the substrate engineering but also provide a new insight into the dynamic in Gr/TMDs heterojunction, which provides a new method to optimize the performance of photodetection.

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Section: Methodssupporting

confidence: 91%

Section: Methodssupporting

confidence: 91%

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Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Ma¹,

Zhang²,

Wang³

et al. 2021

Preprint

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“…[38,39] Therefore, many ultrafast spectroscopic studies have been conducted to understand photophysics in 2D PtSe 2 . [38][39][40][41][42][43][44][45] However, observations on excitons were not made in those studies. This is probably because the theoretical understanding of excitons in PtSe 2 has been largely limited, [46] and/or because of the indirect-gap nature of PtSe 2 .…”

Section: Introductionmentioning

confidence: 98%

Exciton‐Dominated Ultrafast Optical Response in Atomically Thin PtSe₂

Bae

Nah

Lee

et al. 2021

Small

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semiconducting systems. [1,2] A representative example is layered 2D semiconductors, where reduced dielectric screening leads to huge exciton binding energies up to several hundreds of meV, enabling strong excitonic light-matter interactions even at room temperature. Thus, excitons in 2D materials govern fundamental optical properties such as light absorption and emission. [3,4] Furthermore, excitons in 2D systems often couple with their unique physical properties, such as a thickness-dependent change in the bandgap nature and polarization-governed optical selection rules. These relationships provide rich physics and proper functionality for novel optoelectronic applications. [3][4][5] To fully exploit the excellent properties of excitons, it is essential to explore their behavior on ultrashort timescales. Many fundamental excitonic phenomena such as recombination, many-body interactions, and scattering mechanisms occur on femtosecond or picosecond timescales. [6][7][8][9][10][11][12][13] Also, ultrafast light-matter interactions can modulate excitons, enabling novel quantum memory and switching effects. [14][15][16][17][18][19] Therefore, understanding exciton behaviors on Strongly bound excitons are a characteristic hallmark of 2D semiconductors, enabling unique light-matter interactions and novel optical applications. Platinum diselenide (PtSe 2 ) is an emerging 2D material with outstanding optical and electrical properties and excellent air stability. Bulk PtSe 2 is a semimetal, but its atomically thin form shows a semiconducting phase with the appearance of a band-gap, making one expect strongly bound 2D excitons. However, the excitons in PtSe 2 have been barely studied, either experimentally or theoretically. Here, the authors directly observe and theoretically confirm excitons and their ultrafast dynamics in mono-, bi-, and tri-layer PtSe 2 single crystals. Steady-state optical microscopy reveals exciton absorption resonances and their thickness dependence, confirmed by first-principles calculations. Ultrafast transient absorption microscopy finds that the exciton dominates the transient broadband response, resulting from strong exciton bleaching and renormalized band-gap-induced exciton shifting. The overall transient spectrum redshifts with increasing thickness as the shrinking bandgap redshifts the exciton resonance. This study provides novel insights into exciton photophysics in platinum dichalcogenides.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202103400.

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“…The lifetimes of carrier-photon scattering were fitted to be 1. [78] After obtaining the relaxation time of excited carriers, the saturable absorption of PtSe 2 can be further studied. Saturable absorbers are generally classified as slow or fast absorbers.…”

Section: Saturable Absorptionmentioning

confidence: 99%

Layered PtSe₂ for Sensing, Photonic, and (Opto‐)Electronic Applications

Wang

McEvoy

et al. 2020

Advanced Materials

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An increasing enthusiasm for research into 2D nanostructures is driven by their exceptional mechanical, chemical, optical, and physical properties that arise from their atomically thin dimension. These properties make 2D nanostructures promising candidates for applications in the next generation of photonic, valleytronic, and (opto-)electronic devices. 2D black phosphorus, for instance, is a novel 2D material with a thickness-tunable bandgap and outstanding properties that have attracted tremendous interest. However, its commercial and industrial applications have been greatly hindered by its poor environmental stability. [1] Layered transition metal dichalcogenides (TMDs), such as MoS 2 , WS 2 , and MoSe 2 , have been experimentally demonstrated to possess thickness-dependent bandgaps and many other promising physical, chemical, and mechanical properties. However, the majority of these TMDs suffer from relatively low charge-carrier mobilities, rather large Schottky barriers when contacted with metals, complicated fabrication processes and a narrow spectral response mainly in the visible region. [2,3] As a result, even though the first report on the experimental isolation of graphene was 16 years ago, [4] and researchers worldwide have spent massive time and effort investigating 2D materials, thus far few have been effectively employed in industrial and commercial applications. Recently, layered PtSe 2 , a Group-10 TMD, has been demonstrated to be one of the most promising 2D materials for adoption by industries due to its unprecedented photonic, physical, and chemical properties along with lowtemperature synthesis methods, high charge-carrier mobilities and long-term air stability. [5-11] One of the important industrial advantages of PtSe 2 is the developed synthesis methods, some of which are compatible with modern silicon technologies. The studied methods to synthesize layered PtSe 2 include molecular-beam epitaxy (MBE), [7,12] chemical vapor deposition (CVD), [8,13] thermally assisted conversion (TAC), [14-20] chemical vapor transport (CVT), [5] plasma-assisted selenization (PAS), [21] microwave assisted synthesis (MAS), [22] mechanical exfoliation (ME), [13,23] the wet chemical (WC) method, [24,20] and so on. Both MBE and CVD are typically carried out at high temperature and can result in high-quality PtSe 2 monolayers. In contrast, wafer-scale and thickness-tunable layered PtSe 2 can be obtained using TAC Since the first experimental discovery of graphene 16 years ago, many other 2D layered nanomaterials have been reported. However, the majority of 2D nanostructures suffer from relatively complicated fabrication processes that have bottlenecked their development and their uptake by industry for practical applications. Here, the recent progress in sensing, photonic, and (opto-)electronic applications of PtSe 2 , a 2D layered material that is likely to be used in industries benefiting from its high air-stability and semiconductor-technology-compatible fabrication methods, is reviewed. The advantages and disad...

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Thickness-Dependent Ultrafast Photocarrier Dynamics in Selenizing Platinum Thin Films

Cited by 27 publications

References 51 publications

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Exciton‐Dominated Ultrafast Optical Response in Atomically Thin PtSe₂

Layered PtSe₂ for Sensing, Photonic, and (Opto‐)Electronic Applications

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Thickness-Dependent Ultrafast Photocarrier Dynamics in Selenizing Platinum Thin Films

Cited by 27 publications

References 51 publications

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

Exciton‐Dominated Ultrafast Optical Response in Atomically Thin PtSe2

Layered PtSe2 for Sensing, Photonic, and (Opto‐)Electronic Applications

Contact Info

Product

Resources

About

Exciton‐Dominated Ultrafast Optical Response in Atomically Thin PtSe₂

Layered PtSe₂ for Sensing, Photonic, and (Opto‐)Electronic Applications