2D Materials最新文献

{"title":"Electronic structures and quantum capacitance of twisted mixed-dimensional van der Waals heterostructures of graphene/C2H based on tight-binding model","authors":"Baojuan Xin, Boyan Li, Wen Yang, Luyan Li, Hong Dong, Yahui Cheng, Hui Liu, Wei-Hua Wang, Feng Lu","doi":"10.1088/2053-1583/ad2caa","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2caa","url":null,"abstract":"Constructing twisted mixed dimensional graphene-based van der Waals heterostructure (vdWH) is an effective strategy to manipulate the electronic structures and improve the quantum capacitance (<italic toggle=\"yes\">C</italic>\u0000_q) of graphene. In this work, mixed dimensional vdWH of graphene/C₂H has been proposed owing to similar Dirac semimetal character of one-dimensional C₂H with that of graphene. Meanwhile, the influence of twisting angle (<italic toggle=\"yes\">θ</italic>) and interlayer interaction strength on the electronic structures and the <italic toggle=\"yes\">C</italic>\u0000_q of the MD vdWH are systemically explored based on tight binding model. With the fitted hopping integral parameters, it is found that the linear dispersion of the graphene is basically preserved but the bandwidth is decreased with modulating twisting angle and interlayer interaction, and the <italic toggle=\"yes\">C</italic>\u0000_q of mixed dimensional vdWH is improved 5–19 times compared with graphene at zero bias. Moreover, the compressed strain could enhance the <italic toggle=\"yes\">C</italic>\u0000_q of mixed dimensional vdWH to 74.57 <italic toggle=\"yes\">μ</italic>F cm⁻² at zero bias and broaden the low working voltage window of mixed-dimensional vdWH with considerable <italic toggle=\"yes\">C</italic>\u0000_q. Our results provide suitable tight-binding model parameters and theoretical guidance for exploring the twisted MD vdWH of graphene/C₂H and offer an effective strategy to modulate the electronic structures and the <italic toggle=\"yes\">C</italic>\u0000_q of graphene through constructing the MD vdWH.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"68 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-performance broadband SnS photodetector based on photoconductive-bolometric coupling effect","authors":"Bo Zhang, Yunjie Liu, Bing Hu, Fuhai Guo, Mingcong Zhang, Siqi Li, Weizhuo Yu, Lanzhong Hao","doi":"10.1088/2053-1583/ad2c11","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2c11","url":null,"abstract":"Due to its large absorption coefficient and high carrier mobility, SnS exhibits strong promise in the area of optoelectronic devices. Nevertheless, the fabrication of large-area, high-quality films for SnS photodetectors (PDs) with superior photoresponse remains a formidable task, seriously limiting its further practical application. In the present study, we report a superior-performance broadband PD founded on the epitaxial SnS film. Large-area uniform SnS films were grown epitaxially on (100)-oriented KBr using magnetron sputtering technique, further exfoliated, and transferred in a wafer size to fabricated two-ends PD devices. Benefitting from high crystallization and unique photoconductive-bolometric coupling effect, the two modes of operation exhibit a wide range of spectral responses from the visible to near-infrared wavelength (405–1920 nm). Particularly noteworthy is the SnS device fabricated, which demonstrates an impressive responsivity of 95.5 A W⁻¹ and a detectivity of 7.8 × 10¹¹ Jones, outperforming other devices by 1–2 orders of magnitude. In addition, SnS PD shows excellent environmental durability. This work provides a robust approach to develop high-performance broadband SnS PDs, while simultaneously offering deep insight into the light–matter interactions.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"48 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flux-pinning mediated superconducting diode effect in NbSe2/CrGeTe3 heterostructure","authors":"A Mehrnejat, M Ciomaga Hatnean, M C Rosamond, N Banerjee, G Balakrishnan, S E Savel’ev, F K Dejene","doi":"10.1088/2053-1583/ad27e7","DOIUrl":"https://doi.org/10.1088/2053-1583/ad27e7","url":null,"abstract":"In ferromagnet/superconductor bilayer systems, dipolar fields from the ferromagnet can create asymmetric energy barriers for the formation and dynamics of vortices through flux pinning. Conversely, the flux emanating from vortices can pin the domain walls of the ferromagnet, thereby creating asymmetric critical currents. Here, we report the observation of a superconducting diode effect (SDE) in a NbSe₂/CrGeTe₃ van der Waals heterostructure in which the magnetic domains of CrGeTe₃ control the Abrikosov vortex dynamics in NbSe₂. In addition to extrinsic vortex pinning mechanisms at the edges of NbSe₂, flux-pinning-induced bulk pinning of vortices can alter the critical current. This asymmetry can thus be explained by considering the combined effect of this bulk pinning mechanism along with the vortex tilting induced by the Lorentz force from the transport current in the NbSe₂/CrGeTe₃ heterostructure. We also provide evidence of critical current modulation by flux pinning depending on the history of the field setting procedure. Our results suggest a method of controlling the efficiency of the SDE in magnetically coupled van der Waals superconductors, where dipolar fields generated by the magnetic layer can be used to modulate the dynamics of the superconducting vortices in the superconductors.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"12 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140010520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Klein tunneling degradation and enhanced Fabry-Pérot interference in graphene/h-BN moiré-superlattice devices","authors":"Viet-Anh Tran, Viet-Hung Nguyen, Jean-Christophe Charlier","doi":"10.1088/2053-1583/ad27e8","DOIUrl":"https://doi.org/10.1088/2053-1583/ad27e8","url":null,"abstract":"Hexagonal boron-nitride (<italic toggle=\"yes\">h</italic>-BN) provides an ideal substrate for supporting graphene devices to achieve fascinating transport properties, such as Klein tunneling, electron optics and other novel quantum transport phenomena. However, depositing graphene on <italic toggle=\"yes\">h</italic>-BN creates moiré superlattices, whose electronic properties can be significantly manipulated by controlling the lattice alignment between layers. In this work, the effects of these moiré structures on the transport properties of graphene are investigated using atomistic simulations. At large misalignment angles (leading to small moiré cells), the transport properties (most remarkably, Klein tunneling) of pristine graphene devices are conserved. On the other hand, in the nearly aligned cases, the moiré interaction induces stronger effects, significantly affecting electron transport in graphene. In particular, Klein tunneling is significantly degraded. In contrast, strong Fabry-Pérot interference (accordingly, strong quantum confinement) effects and non-linear I-V characteristics are observed. P-N interface smoothness engineering is also considered, suggesting as a potential way to improve these transport features in graphene/<italic toggle=\"yes\">h</italic>-BN devices.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140010512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dipolar interactions enhanced by two-dimensional dielectric screening in few-layer van der Waals structures","authors":"Yuhang Hou, Hongyi Yu","doi":"10.1088/2053-1583/ad2525","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2525","url":null,"abstract":"We theoretically examined how the dielectric screening of two-dimensional (2D) layered materials affects the dipolar interaction between interlayer excitons (IXs) in few-layer van der Waals structures. Our analysis indicates that the dipolar interaction is largely enhanced by 2D dielectric screening at an inter-exciton separation of several nanometers or larger. The underlying mechanism can be attributed to the induced-charge densities in layered materials, which give rise to induced-dipole densities at large distances with directions parallel to that of the IX. The interaction between quadrupolar excitons in trilayer structures are found to be enhanced even larger, with a magnitude one to two orders stronger than that without 2D dielectric screening. The strengths of these dipolar and quadrupolar interactions can be further tuned by engineering the dielectric environment.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140010447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New twisted van der Waals fabrication method based on strongly adhesive polymer","authors":"Giung Park, Suhan Son, Jongchan Kim, Yunyeong Chang, Kaixuan Zhang, Miyoung Kim, Jieun Lee, Je-Geun Park","doi":"10.1088/2053-1583/ad2524","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2524","url":null,"abstract":"Observations of emergent quantum phases in twisted bilayer graphene prompted a flurry of activities in van der Waals (vdW) materials beyond graphene. Most current twisted experiments use a so-called tear-and-stack method using a polymer called polypropylene carbonate (PPC). However, despite the clear advantage of the current PPC tear-and-stack method, there are also technical limitations, mainly a limited number of vdW materials that can be studied using this PPC-based method. This technical bottleneck has been preventing further development of the exciting field beyond a few available vdW samples. To overcome this challenge and facilitate future expansion, we developed a new tear-and-stack method using a strongly adhesive polycaprolactone. With similar angular accuracy, our technology allows fabrication without a capping layer, facilitating surface analysis and ensuring inherently clean interfaces and low operating temperatures. More importantly, it can be applied to many other vdW materials that have remained inaccessible with the PPC-based method. We present our results on twist homostructures made with a wide choice of vdW materials—from two well-studied vdW materials (graphene and MoS₂) to the first-ever demonstrations of other vdW materials (NbSe₂, NiPS₃, and Fe₃GeTe₂). Therefore, our new technique will help expand moiré physics beyond few selected vdW materials and open up more exciting developments.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"36 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140010445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"X-ray photoelectron diffraction as a modern tool for determining surface stacking sequence in layered materials","authors":"L H de Lima, A de Siervo","doi":"10.1088/2053-1583/ad2526","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2526","url":null,"abstract":"We investigated the surface structure of a NbSe₂ single crystal at room temperature, using angle-scanned x-ray photoelectron diffraction (XPD) combined with multiple scattering calculations. Different stacking sequences were tested (1T, 2H_{\u0000<italic toggle=\"yes\">a</italic>\u0000}, 2H_{\u0000<italic toggle=\"yes\">c</italic>\u0000}, and 3R), including possible stacking faults and a mixed 2H–3R stacking proposed earlier in the literature. We confirm the capability of XPD to distinguish different proposed structural models and, unambiguously, determine the true surface structure. Also, our findings provide reliable in-plane and interlayer distances. We observed expansions of the perpendicular distances between atomic planes within the monolayer and between monolayers of 3%–5%. These results are important as accurate experimental input for the development of theoretical methods that involve a quantitative description of van der Waals systems.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139757274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the mechanism of vanadium self-intercalation in 1T-VSe2: atomic-scale evidence for phase transition and superstructure model for intercalation compound","authors":"Daliang He, Bo Wang, Wang Cao, Yongjun Jiang, Sheng Dai, Wei Zhao, Xiaodong Cui, Chuanhong Jin","doi":"10.1088/2053-1583/ad2193","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2193","url":null,"abstract":"Self-intercalation is an efficient strategy for tailoring the property of layer structured materials like transition metal dichalcogenides (TMDCs), while the associated kinetics and mechanism remain scarcely explored. In this study, we investigate the atomic-scale dynamics and mechanism of vanadium (V) self-intercalation in multi-layer 1T-VSe₂ using <italic toggle=\"yes\">in situ</italic> high resolution scanning transmission electron microscopy. The results reveal that the self-intercalation of V induces structural transformation of pristine VSe₂ into three V-enrich intercalated compounds, i.e. V₅Se₈, V₃Se₄ and VSe. The self-intercalated V follows an ordered arrangement of <inline-formula>\u0000<tex-math><?CDATA $2 times 2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"tdmad2193ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, <inline-formula>\u0000<tex-math><?CDATA $2 times 1$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"tdmad2193ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, and <inline-formula>\u0000<tex-math><?CDATA $1 times 1$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>1</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"tdmad2193ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> within the interlayer octahedral sites, corresponding to an intercalation concentration of 25%, 50% and 100% in V₅Se₈, V₃Se₄ and VSe, respectively. The V intercalants induced lattice distortions to the host 1T-VSe₂ such as the dimerization of neighboring lattice V is observed experimentally, which are further supported by density functional theory (DFT) calculations. Finally, a superstructure model generalizing the possible structures of self-intercalated compounds in layered TMDCs is proposed and then validated by the DFT determined formation energy landscape. This study provides comprehensive insights on the kinetics and mechanism of the self-intercalation in layered TMDC materials, contributing to the precise control for the structure and stoichiometry of self-intercalated TMDC compounds.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139757437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Graphene Roadmap Briefs (No. 3): meta-market analysis 2023","authors":"Thomas Schmaltz, Lorenzo Wormer, Ulrich Schmoch, Henning Döscher","doi":"10.1088/2053-1583/ad1e78","DOIUrl":"https://doi.org/10.1088/2053-1583/ad1e78","url":null,"abstract":"Graphene and related materials (GRMs) promise ample application potential throughout numerous industries. A dedicated graphene market gradually forms around emerging suppliers aspiring to satisfy future demands. Its growth critically depends on the interplay of supply stream maturation and initial utilizations to drive the demand. The present issue of Graphene Roadmap Briefs provides quantitative insights into the current state and future development of the emerging graphene market. We aggregate the underlying expectations and projections from commercial market reports and critically discuss the results. Established science and technology metrics complement our analyses and provide deeper insights into the global market landscape and key actors. In particular, we resolve composites, batteries, and electronics as major application areas likely to drive the overall development of the graphene market towards mass production.<bold>About: Graphene Roadmap Briefs</bold>Graphene Roadmap Briefs highlight key innovation areas impacted by graphene and related materials (GRMs) as well as overarching aspects of GRM innovation status and prospects. The series bases on the evolving technology and innovation roadmap process initiated by the European Graphene Flagship. It covers crucial innovation trends beyond fundamental scientific discovery and applied research on GRM utilization opportunities.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"9 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139757180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The deep-acceptor nature of the chalcogen vacancies in 2D transition-metal dichalcogenides","authors":"Shoaib Khalid, Bharat Medasani, John L Lyons, Darshana Wickramaratne, Anderson Janotti","doi":"10.1088/2053-1583/ad2108","DOIUrl":"https://doi.org/10.1088/2053-1583/ad2108","url":null,"abstract":"Chalcogen vacancies in the semiconducting monolayer transition-metal dichalcogenides (TMDs) have frequently been invoked to explain a wide range of phenomena, including both unintentional p-type and n-type conductivity, as well as sub-band gap defect levels measured via tunneling or optical spectroscopy. These conflicting interpretations of the deep versus shallow nature of the chalcogen vacancies are due in part to shortcomings in prior first-principles calculations of defects in the semiconducting two-dimensional TMDs that have been used to explain experimental observations. Here we report results of hybrid density functional calculations for the chalcogen vacancy in a series of monolayer TMDs, correctly referencing the thermodynamic charge transition levels to the fundamental band gap (as opposed to the optical band gap). We find that the chalcogen vacancies are deep acceptors and cannot lead to n-type or p-type conductivity. Both the (0/−1) and (−1/−2) transition levels occur in the gap, leading to paramagnetic charge states <inline-formula>\u0000<tex-math><?CDATA $S = 1/2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>S</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"tdmad2108ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> and <italic toggle=\"yes\">S</italic> = 1, respectively, in a collinear-spin representation. We discuss trends in terms of the band alignments between the TMDs, which can serve as a guide to future experimental studies of vacancy behavior.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"21 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139757095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}