Micrometer-scale monolayer SnS growth by physical vapor deposition

Kawamoto, Hayami; Higashitarumizu, Naoki; Nagamura, Naoka; Nakamura, Masaru; Shimamura, Kiyoshi; Ohashi, Naoki; Nagashio, Kosuke

doi:10.1039/d0nr06022d

Cited by 26 publications

(10 citation statements)

References 47 publications

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“…To verify the crystallinity improvement of SnS on h -BN, Raman spectra are taken at 3 K. As shown in Figure d, 5–6 nm thick SnS on h -BN exhibits a much sharper and stronger signal than SnS on a mica substrate with a similar thickness. Four main characteristic peaks of SnS can be observed at 154.5 (B 3g ), 184.5 (A g ), 226.4 (A g ) and 297.8 cm –1 (B 2g ) for SnS on h -BN, while only two peaks are detected at 180.9 (B 3g ) and 231.8 cm –1 (A g ) for SnS on mica due to the weaker signals and the background signal from the mica substrate . Moreover, as reported by previous work, a stronger interaction between SnS and the substrate could lead to a blue-shift of the Raman peaks.…”

Section: Resultssupporting

confidence: 55%

Performance Enhancement of SnS/h-BN Heterostructure p-Type FET via the Thermodynamically Predicted Surface Oxide Conversion Method

Chang

Nishimura

Taniguchi

et al. 2022

ACS Appl. Mater. Interfaces

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Searching for the counterpart of well-developed two-dimensional (2D) n-type field effect transistors (FETs) is indispensable for complementary logic circuit applications for 2D devices. Although SnS is regarded as a potential candidate for high-performance p-type FETs, recent experiments only show poor results deviating from the theoretically predicted high mobility. In this research, the serious performance degradation due to the surface oxidation of SnS, which commonly occurs in most 2D materials, is addressed through surface oxide conversion using highly reactive Ti. In this conversion process, which is confirmed by systematic characterization, the reduction of SnS surface oxide is accompanied by the formation of functional titanium oxide, which works as both a conductive intermediate layer to improve the contact property and a buffer layer of the high-k top gate insulator at the channel region. Consequently, a record-high field effect mobility of 87.4 cm2 V–1 s–1 in SnS p-type FETs is achieved. The surface oxide conversion method applied here is consistent with our previous thermodynamic prediction, and this novel technique can be widely introduced to all 2D materials that are vulnerable to oxidation and facilitate the future development of 2D devices.

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Section: Resultssupporting

confidence: 55%

Performance Enhancement of SnS/h-BN Heterostructure p-Type FET via the Thermodynamically Predicted Surface Oxide Conversion Method

Chang

Nishimura

Taniguchi

et al. 2022

ACS Appl. Mater. Interfaces

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“…The objective of this study is obtaining SnS with spiral structure through the bottom-up growth method. Since compounds with different stoichiometries, such as SnS 2 or Sn 2 S 3 , likely appear through the chemical reaction from the two different sources during the CVD growth of SnS, − the PVD method was applied to obtain phase-pure SnS flakes instead. − Although previous research found that SnS 2 impurity in precursor powder will induce other phase of SnS, there is no stoichiometric compound impurity, such as Sn 2 S 3 or SnS 2 , found in our SnS source, as confirmed by X-ray diffractometry (XRD) analysis on SnS powder source in Figure S1. Because screw dislocation induced in CVD growth by the chalcogen-rich environment is no longer applicable in the PVD method, a novel approach was invented in this study to assist the spiral growth of SnS.…”

Section: Introductionmentioning

confidence: 76%

Atomic-Step-Induced Screw-Dislocation-Driven Spiral Growth of SnS

et al. 2020

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The in-plane piezoelectricity or ferroelectricity of two-dimensional (2D) materials can vanish due to the appearance of inversion symmetry with increasing flake thickness, which drastically limits the development of their energy-harvesting application. Although the inversion symmetry breaking in spiral structure of 2D material may solve this problem, the control of spiral growth remains immature. Here, a novel technique to achieve high percentage of spiral SnS flakes with superior control of nucleation position is demonstrated. By introducing atomic steps on substrates, the screw dislocation can be easily formed when SnS partially grows across these steps and leads to over 90% of spiral SnS flakes grown by physical vapor deposition (PVD). Furthermore, the preference for SnS to nucleate at steps can introduce remarkable nucleation site control of spiral growth even on substrates with artificially transferred graphene atomic steps. Interestingly, it turns out that the spiral SnS structure exhibits centrosymmetric characteristic, indicating that single-spiral 2D materials with monolayer step height do not guarantee an inversion symmetry breaking structure. The high spiral flake percentage and precise control of nucleation sites in this study will facilitate future development of spiral 2D materials.

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“…Two-dimensional atomically thin semiconductor nanostructures, like tin monochalcogenides SnE (E = S, Sn) and tin dichalogenides SnE 2 (E = S, Se), have been attracting worldwide attention due to their exceptional electrical and optical properties, and their potential applications in nanoscale electronics, photonics and functional materials as well as semiconducting and optical devices. [1][2][3][4][5] Mono or few layered 2D van der Waals (vdW) tin-based chalcogenide materials are distinguished in their chemical and physical properties 6,7 as compared to their bulk counterparts. Additionally, these layered vdW materials have the advantage of their constituent elements being abundant in nature and not posing any health and environmental hazards.…”

Section: Introductionmentioning

confidence: 99%