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Baby A, Marcaud G, Dappe YJ, D'Angelo M, Cantin JL, Silly M, Fratesi G. Phthalocyanine reactivity and interaction on the 6H-SiC(0001)-(3×3) surface by core-level experiments and simulations. Phys Chem Chem Phys 2022; 24:14937-14946. [DOI: 10.1039/d2cp00750a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The adsorption of phthalocyanine (H2Pc) on the 6H-SiC(0001)-(3×3) surface is investigated using X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS), and density functional theory (DFT) calculations....
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Fu R, Wu Z, Pan Z, Gao Z, Li Z, Kong X, Li L. Fluorine-Induced Surface Metallization for Ammonia Synthesis under Photoexcitation up to 1550 nm. Angew Chem Int Ed Engl 2021; 60:11173-11179. [PMID: 33650282 DOI: 10.1002/anie.202100572] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/17/2021] [Indexed: 11/10/2022]
Abstract
The first observation of surface metallization of TiO2-x induced by fluoride ions is presented. The emerging metallic states are contributed by the 3d orbital of surface Ti and the 2p orbital of surface bridging F, which are intrinsically originated from the strong electron repulsion between F- and adjacent Ti3+ . The metalized TiO2-x with reduced work function and downward band bending possesses high electron-donating power to supported Ru species via atomic-scale ohmic contacts, exhibiting unprecedented photocatalytic performances for ammonia synthesis across the entire solar spectrum region (200-1550 nm) at room temperature. Mechanism and kinetic analysis revealed that the loaded Ru could behave as efficient electron sinks to accumulate photogenerated electrons and that the metallic surface markedly enhanced the dissociation of H2 and N2 by the hot electrons generated by the visible or even infrared light irradiation.
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Affiliation(s)
- Rong Fu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Zewen Wu
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.,Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, QC, H3A 2T8, Canada
| | - Ziye Pan
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Zhuoyang Gao
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Zhen Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Xianghua Kong
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.,Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, QC, H3A 2T8, Canada
| | - Lu Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.,Electron Microscopy Center, Jilin University, Changchun, 130012, P. R. China
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Fluorine‐Induced Surface Metallization for Ammonia Synthesis under Photoexcitation up to 1550 nm. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Qiu R, Tang J, Chen J, Ao B. Metallic and anti-metallic properties of hydrogen adsorbed AnO 2 (An = Th, U, and Pu) surfaces. Phys Chem Chem Phys 2021; 23:878-885. [PMID: 33346754 DOI: 10.1039/d0cp04824k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of atomic hydrogen adsorption on AnO2 (An = Th, U, and Pu) surfaces is studied in the framework of density functional theory and Hubbard-corrected density functional theory. Several adsorption coverages (1/3, 1/2, 2/3, and 1 monolayer) are considered. For the band insulator ThO2, surface metallicity induced by hydrogen adsorption is observed due to the electron donation of the hydrogen to the surface. But this effect is found to be strongly suppressed by electronic correlation for the Mott insulators UO2 and PuO2 because the electrons from the adsorbed hydrogen atoms occupy the localized 5f orbitals of the surface U/Pu atoms.
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Affiliation(s)
- Ruizhi Qiu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, Sichuan, China.
| | - Jun Tang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, Sichuan, China.
| | - Jinfan Chen
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, Sichuan, China.
| | - Bingyun Ao
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, Sichuan, China.
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Wang S, Fang WH, Long R. Hydrogen Passivated Silicon Grain Boundaries Greatly Reduce Charge Recombination for Improved Silicon/Perovskite Tandem Solar Cell Performance: Time Domain Ab Initio Analysis. J Phys Chem Lett 2019; 10:2445-2452. [PMID: 31034228 DOI: 10.1021/acs.jpclett.9b00874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
By performing nonadiabatic molecular dynamics simulations, we demonstrate that grain boundaries (GBs) can induce the indirect-to-direct transition of the silicon band gap. However, missing a silicon atom creates an electron trap state in the GBs. Electron trapping by the silicon vacancy occurs on tens of picoseconds followed by recombination of the trapped electron and valence band hole on sub-100 ps, which operates parallel to recombination of the free electron and hole on a similar time scale. The recombination is greatly accelerated by 2 orders of magnitude compared to the GBs without a silicon vacancy. Hydrogen passivation eliminates the trap state and notably delays the charge recombination due to an increased band gap and a shortened coherence time, extending the excited-state lifetime to sub-10 ns. Our study provides an atomistic description of how charge recombination in the silicon can be efficiently reduced, suggesting a rational route to enhance silicon/perovskite tandem solar cells performance.
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Affiliation(s)
- Siyu Wang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing , 100875 , People's Republic of China
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing , 100875 , People's Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing , 100875 , People's Republic of China
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Hao CH, Guo XN, Sankar M, Yang H, Ma B, Zhang YF, Tong XL, Jin GQ, Guo XY. Synergistic Effect of Segregated Pd and Au Nanoparticles on Semiconducting SiC for Efficient Photocatalytic Hydrogenation of Nitroarenes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:23029-23036. [PMID: 29914262 DOI: 10.1021/acsami.8b04044] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Efficient catalytic hydrogenation of nitroarenes to anilines with molecular hydrogen at room temperature is still a challenge. In this study, this transformation was achieved by using a photocatalyst of SiC-supported segregated Pd and Au nanoparticles. Under visible-light irradiation, the nitrobenzene hydrogenation reached a turnover frequency as high as 1715 h-1 at 25 °C and 0.1 MPa of H2 pressure. This exceptional catalytic activity is attributed to a synergistic effect of Pd and Au nanoparticles on the semiconducting SiC, which is different from the known electronic or ensemble effects in Pd-Au catalysts. This kind of synergism originates from the plasmonic electron injection of Au and the Mott-Schottky contact at the interface between Pd and SiC. This three-component system changes the electronic structures of the SiC surface and produces more active sites to accommodate the active hydrogen that spills over from the surface of Pd. These active hydrogen species have weaker interactions with the SiC surface and thus are more mobile than on an inert support, resulting in an ease in reacting with the N═O bonds in nitrobenzene absorbed on SiC to produce aniline.
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Affiliation(s)
- Cai-Hong Hao
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
- University of the Chinese Academy of Sciences , Beijing 100039 , China
| | - Xiao-Ning Guo
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
| | - Meenakshisundaram Sankar
- Cardiff Catalysis Institute, School of Chemistry , Cardiff University , Main Building, Park Place, Cardiff CF10 3AT , U.K
| | - Hong Yang
- Department of Chemical & Biomolecular Engineering, 206 Roger Adams Laboratory , University of Illinois at Urbana-Champaign , MC-712, 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Ben Ma
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
- University of the Chinese Academy of Sciences , Beijing 100039 , China
| | - Yue-Fei Zhang
- Institute of Microstructure & Property of Advanced Materials , Beijing University of Technology , Beijing 100124 , China
| | - Xi-Li Tong
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
| | - Guo-Qiang Jin
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
| | - Xiang-Yun Guo
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan , Shanxi 030001 , China
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Alekseev S, Shamatulskaya E, Volvach M, Gryn S, Korytko D, Bezverkhyy I, Iablokov V, Lysenko V. Size and Surface Chemistry Tuning of Silicon Carbide Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13561-13571. [PMID: 29099996 DOI: 10.1021/acs.langmuir.7b02784] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Chemical transformations on the surface of commercially available 3C-SiC nanoparticles were studied by means of FTIR, XPS, and temperature-programmed desorption mass spectrometry methods. Thermal oxidation of SiC NPs resulted in the formation of a hydroxylated SiO2 surface layer with C3Si-H and CHx groups over the SiO2/SiC interface. Controllable oxidation followed by oxide dissolution in HF or KOH solution allowed the SiC NPs size tuning from 17 to 9 nm. Oxide-free SiC surfaces, terminated by hydroxyls and C3Si-H groups, can be efficiently functionalized by alkenes under thermal or photochemical initiation. Treatment of SiC NPs by HF/HNO3 mixture produces a carbon-enriched surface layer with carboxylic acid groups susceptible to amide chemistry functionalization. The hydroxylated, carboxylated, and aminated SiC NPs form stable aqueous sols.
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Affiliation(s)
- Sergei Alekseev
- Taras Shevchenko National University of Kyiv, 62a, Volodymyrs'ka Street, 01601 Kyiv, Ukraine
- Science Park Kyiv Taras Shevchenko University, 60, Volodymyrs'ka Street, 01033 Kyiv, Ukraine
| | - Elena Shamatulskaya
- Taras Shevchenko National University of Kyiv, 62a, Volodymyrs'ka Street, 01601 Kyiv, Ukraine
| | - Mykola Volvach
- Taras Shevchenko National University of Kyiv, 62a, Volodymyrs'ka Street, 01601 Kyiv, Ukraine
| | - Svitlana Gryn
- Taras Shevchenko National University of Kyiv, 62a, Volodymyrs'ka Street, 01601 Kyiv, Ukraine
- Science Park Kyiv Taras Shevchenko University, 60, Volodymyrs'ka Street, 01033 Kyiv, Ukraine
| | - Dmytro Korytko
- Taras Shevchenko National University of Kyiv, 62a, Volodymyrs'ka Street, 01601 Kyiv, Ukraine
- Science Park Kyiv Taras Shevchenko University, 60, Volodymyrs'ka Street, 01033 Kyiv, Ukraine
| | - Igor Bezverkhyy
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 6303, Universite de Bourgogne , 21078 Dijon, France
| | - Viacheslav Iablokov
- Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, Washington 99164, United States
| | - Vladimir Lysenko
- Nanotechnology Institute of Lyon (INL), UMR CNRS 5270, University of Lyon , 69361 Lyon, France
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8
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Wang Y, Yan Z, Liu W, Chen Q, Zhang S, Hou A. First-principles study of CO adsorption on 4H-SiC (001) surface. ACTA ACUST UNITED AC 2017. [DOI: 10.1680/jnaen.17.00006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Yongsheng Wang
- College of Science, Xi’an University of Science and Technology, Xi’an, China
| | - Zhengxin Yan
- College of Science, Xi’an University of Science and Technology, Xi’an, China
| | - Wei Liu
- College of Science, Xi’an University of Science and Technology, Xi’an, China
| | - Qian Chen
- College of Science, Xi’an University of Science and Technology, Xi’an, China
| | - Shaohua Zhang
- College of Science, Xi’an University of Science and Technology, Xi’an, China
| | - Anhong Hou
- College of Science, Xi’an University of Science and Technology, Xi’an, China
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9
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Fermi level pinning characterisation on ammonium fluoride-treated surfaces of silicon by energy-filtered doping contrast in the scanning electron microscope. Sci Rep 2016; 6:32003. [PMID: 27576347 PMCID: PMC5005997 DOI: 10.1038/srep32003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 08/01/2016] [Indexed: 11/09/2022] Open
Abstract
Two-dimensional dopant profiling using the secondary electron (SE) signal in the scanning electron microscope (SEM) is a technique gaining impulse for its ability to enable rapid and contactless low-cost diagnostics for integrated device manufacturing. The basis is doping contrast from electrical p-n junctions, which can be influenced by wet-chemical processing methods typically adopted in ULSI technology. This paper describes the results of doping contrast studies by energy-filtering in the SEM from silicon p-n junction specimens that were etched in ammonium fluoride solution. Experimental SE micro-spectroscopy and numerical simulations indicate that Fermi level pinning occurred on the surface of the treated-specimen, and that the doping contrast can be explained in terms of the ionisation energy integral for SEs, which is a function of the dopant concentration, and surface band-bending effects that prevail in the mechanism for doping contrast as patch fields from the specimen are suppressed.
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10
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Srour W, Trabada DG, Martínez JI, Flores F, Ortega J, Abuín M, Fagot-Revurat Y, Kierren B, Taleb-Ibrahimi A, Malterre D, Tejeda A. Ultrafast Atomic Diffusion Inducing a Reversible (2sqrt[3]×2sqrt[3])R30°↔(sqrt[3]×sqrt[3])R30° Transition on Sn/Si(111)∶B. PHYSICAL REVIEW LETTERS 2015; 114:196101. [PMID: 26024183 DOI: 10.1103/physrevlett.114.196101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 06/04/2023]
Abstract
Dynamical phase transitions are a challenge to identify experimentally and describe theoretically. Here, we study a new reconstruction of Sn on silicon and observe a reversible transition where the surface unit cell divides its area by a factor of 4 at 250 °C. This phase transition is explained by the 24-fold degeneracy of the ground state and a novel diffusive mechanism, where four Sn atoms arranged in a snakelike cluster wiggle at the surface exploring collectively the different quantum mechanical ground states.
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Affiliation(s)
- W Srour
- Institut Jean Lamour, CNRS-Université de Lorraine, 54506 Vandoeuvre les Nancy, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Daniel G Trabada
- Dto. de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - J I Martínez
- Dto. de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - F Flores
- Dto. de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - J Ortega
- Dto. de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - M Abuín
- Dto. de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Y Fagot-Revurat
- Institut Jean Lamour, CNRS-Université de Lorraine, 54506 Vandoeuvre les Nancy, France
| | - B Kierren
- Institut Jean Lamour, CNRS-Université de Lorraine, 54506 Vandoeuvre les Nancy, France
| | - A Taleb-Ibrahimi
- UR1 CNRS/Synchrotron SOLEIL, Saint-Aubin, 91192 Gif sur Yvette, France
| | - D Malterre
- Institut Jean Lamour, CNRS-Université de Lorraine, 54506 Vandoeuvre les Nancy, France
| | - A Tejeda
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
- Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR 8502, F-91405 Orsay, France
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11
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Boukari K, Duverger E, Sonnet P. Molecular chemisorption on passivated and defective boron doped silicon surfaces: a "forced" dative bond. Phys Chem Chem Phys 2014; 16:24866-73. [PMID: 25318974 DOI: 10.1039/c4cp03347g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the adsorption mechanism of a single trans 4-pyridylazobenzene molecule (denoted by PAB) on a doped boron Si(111)√3×√3R30° surface (denoted by SiB) with or without boron-defects, by means of density functional theory calculations. The semiempirical approach proposed by Grimme allows us to take the dispersion correction into account. The role of the van der Waals correction in the adsorption geometries and energies is presented. In particular, two adsorption configurations are electronically studied. In the first one, the molecule is parallel to the surface and interacts with the SiB surface via the -N=N- bond. In the presence of a boron-defect, a Si-N chemical bond between the molecule and the surface is then formed, while electrostatic or/and van der Waals interactions are observed in the defectless surface. In the second adsorption configuration, the molecule presents different orientations with respect to the surface and interacts via the nitrogen atom of the pyridyl part of the PAB molecule. If the molecule is perpendicular to the perfect SiB surface, the lone-pair electrons associated with the heterocyclic nitrogen atom fill the empty dangling bond of a silicon adatom via a dative bond. Finally, in the presence of one boron-defect, the possibility of a "forced" dative bond, corresponding to a chemical bond formation between the PAB molecule and the silicon electron occupied dangling bond, is emphasized.
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Affiliation(s)
- Khaoula Boukari
- Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, Université de Haute Alsace, 3b rue Alfred Werner, 68093 Mulhouse cedex, France.
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Cai Y, Bai Z, Pan H, Feng YP, Yakobson BI, Zhang YW. Constructing metallic nanoroads on a MoS₂ monolayer via hydrogenation. NANOSCALE 2014; 6:1691-1697. [PMID: 24343306 DOI: 10.1039/c3nr05218d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Monolayer transition metal dichalcogenides recently emerged as a new family of two-dimensional materials potentially suitable for numerous applications in electronic and optoelectronic devices due to the presence of a finite band gap. Many proposed applications require efficient transport of charge carriers within these semiconducting monolayers. However, constructing a stable conducting nanoroad on these atomically thin semiconductors is still a challenge. Here we demonstrate that hydrogenation on the surface of a MoS₂ monolayer induces a semiconductor-metal transition, and strip-patterned hydrogenation is able to generate a conducting nanoroad. The band-gap closing arises from the formation of in-gap hybridized states mainly consisting of Mo 4d orbitals, as well as the electron donation from hydrogen to the lattice host. Ballistic conductance calculations reveal that such a nanoroad on the MoS₂ surface exhibits an integer conductance, indicating small carrier scattering, and thus is ideal for serving as a conducting channel or an interconnect without compromising the mechanical and structural integrity of the monolayer.
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Affiliation(s)
- Yongqing Cai
- Institute of High Performance Computing, 1 Fusionopolis Way, Singapore, 138632, Singapore.
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Soukiassian P, Wimmer E, Celasco E, Giallombardo C, Bonanni S, Vattuone L, Savio L, Tejeda A, Silly M, D’angelo M, Sirotti F, Rocca M. Hydrogen-induced nanotunnel opening within semiconductor subsurface. Nat Commun 2013. [PMCID: PMC3868329 DOI: 10.1038/ncomms3800] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Haycock BJ, Trabada DG, Ortega J, O'Mahony JD, Lewis JP. Metallization of the potassium overlayer on the β-SiC(100) c(4 × 2) surface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:485001. [PMID: 23086310 DOI: 10.1088/0953-8984/24/48/485001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present new data on the potassium-induced semiconducting to metallic transition of the silicon-terminated β-SiC(100) c(4 × 2) surface, resulting from density functional theory simulations. We have analysed many different SiC(100)-K surface topologies, corresponding to K coverages ranging from 0.08 to 1.25 monolayers (ML), paying special attention to the 2/3 ML and 1 ML cases where a metal-insulator transition has been reported to occur. We find that the SiC(100)-K surface is metallic in all the cases. In spite of that, the potassium layer shows a very low density of states in the semiconductor gap up to potassium coverages of ~1 ML, beyond which the potassium layer undergoes a transition to metallic behaviour, explaining the experimental observation. We propose a new atomic model for the surface reconstruction of the 1 ML case which is lower in total energy than the previously suggested model based on linear potassium chains.
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Affiliation(s)
- Barry J Haycock
- School of Physics, Dublin Institute of Technology, Dublin 2, Ireland.
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15
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D'Angelo M, Yukawa R, Ozawa K, Yamamoto S, Hirahara T, Hasegawa S, Silly MG, Sirotti F, Matsuda I. Hydrogen-induced surface metallization of SrTiO3(001). PHYSICAL REVIEW LETTERS 2012; 108:116802. [PMID: 22540498 DOI: 10.1103/physrevlett.108.116802] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Indexed: 05/31/2023]
Abstract
Surface metallization of SrTiO3(001) by hydrogen adsorption is experimentally confirmed for the first time by photoemission spectroscopy and surface conductivity measurements. The metallic state is assigned to a quantized state in the space-charge layer induced by electron doping from hydrogen atoms. The measured two-dimensional (2D) conductivity is well above the 2D Ioffe-Regel limit indicating that the system is in a metallic conduction regime. The mean free path of the surface electron is estimated to be several nanometers at room temperature.
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Affiliation(s)
- M D'Angelo
- Institut des Nanosciences de Paris, Université Pierre et Marie Curie-Paris 6, CNRS-UMR 7588, Paris, France.
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Hydrogen sensors using nitride-based semiconductor diodes: the role of metal/semiconductor interfaces. SENSORS 2012; 11:674-95. [PMID: 22346597 PMCID: PMC3274108 DOI: 10.3390/s110100674] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/06/2011] [Indexed: 11/29/2022]
Abstract
In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C–V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C–V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C–V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I–V) characterization, suggesting that low-frequency C–V method would be effective in detecting very low hydrogen concentrations.
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17
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Diverse Role of Silicon Carbide in the Domain of Nanomaterials. INTERNATIONAL JOURNAL OF ELECTROCHEMISTRY 2012. [DOI: 10.1155/2012/271285] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Silicon carbide (SiC) is a promising material due to its unique property to adopt different crystalline polytypes which monitor the band gap and the electronic and optical properties. Despite being an indirect band gap semiconductor, SiC is used in several high-performance electronic and optical devices. SiC has been long recognized as one of the best biocompatible materials, especially in cardiovascular and blood-contacting implants and biomedical devices. In this paper, diverse role of SiC in its nanostructured form has been discussed. It is felt that further experimental and theoretical work would help to better understanding of the various properties of these nanostructures in order to realize their full potentials.
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18
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Control of electronic conduction at an oxide heterointerface using surface polar adsorbates. Nat Commun 2011; 2:494. [DOI: 10.1038/ncomms1501] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/07/2011] [Indexed: 11/08/2022] Open
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19
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Hydrophobic to hydrophilic transition of HF-treated Si surface during Langmuir–Blodgett film deposition. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.10.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wang J, Xiong SJ, Wu XL, Li TH, Chu PK. Glycerol-bonded 3C-SiC nanocrystal solid films exhibiting broad and stable violet to blue-green emission. NANO LETTERS 2010; 10:1466-1471. [PMID: 20210349 DOI: 10.1021/nl100407d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have produced glycerol-bonded 3C-SiC nanocrystal (NC) films, which when excited by photons of different wavelengths, produce strong and tunable violet to blue-green (360-540 nm) emission as a result of the quantum confinement effects rendered by the 3C-SiC NCs. The emission is so intense that the emission spots are visible to the naked eyes. The light emission is very stable and even after storing in air for more than six months, no intensity degradation can be observed. X-ray photoelectron spectroscopy and absorption fine structure measurements indicate that the Si-terminated NC surfaces are completely bonded to glycerol molecules. Calculations of geometry optimization and electron structures based on the density functional theory for 3C-SiC NCs with attached glycerol molecules show that these molecules are bonded on the NCs causing strong surface structural change, while the isolated levels in the conduction band of the bare 3C-SiC NCs are replaced with quasi-continuous bands that provide continuous tunability of the emitted light by changing the frequencies of exciting laser. As an application, we demonstrate the potential of using 3C-SiC NCs to fabricate full-color emitting solid films by incorporating porous silicon.
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Affiliation(s)
- J Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, People's Republic of China
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21
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Wu XL, Xiong SJ, Zhu J, Wang J, Shen JC, Chu PK. Identification of surface structures on 3C-SiC nanocrystals with hydrogen and hydroxyl bonding by photoluminescence. NANO LETTERS 2009; 9:4053-4060. [PMID: 19894694 DOI: 10.1021/nl902226u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
SiC nanocrystals (NCs) exhibit unique surface chemistry and possess special properties. This provides the opportunity to design suitable surface structures by terminating the surface dangling bonds with different atoms thereby boding well for practical applications. In this article, we report the photoluminescence properties of 3C-SiC NCs in water suspensions with different pH values. Besides a blue band stemming from the quantum confinement effect, the 3C-SiC NCs show an additional photoluminescence band at 510 nm when the excitation wavelengths are longer than 350 nm. Its intensity relative to the blue band increases with the excitation wavelength. The 510 nm band appears only in acidic suspensions but not in alkaline ones. Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure analyses clearly reveal that the 3C-SiC NCs in the water suspension have Si-H and Si-OH bonds on their surface, implying that water molecules only react with a Si-terminated surface. First-principle calculations suggest that the additional 510 nm band arises from structures induced by H(+) and OH(-) dissociated from water and attached to Si dimers on the modified (001) Si-terminated portion of the NCs. The size requirement is consistent with the observation that the 510 nm band can only be observed when the excitation wavelengths are relatively large, that is, excitation of bigger NCs.
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Affiliation(s)
- X L Wu
- National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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22
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Oliveira AC, Brito Mota F, de Castilho CMC. Role of hydrogen adsorption on the carbon terminated β-SiC(100)-c(2 × 2) surface structure: a theoretical approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:055004. [PMID: 21817291 DOI: 10.1088/0953-8984/21/5/055004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The role of hydrogen adsorption on different clean surface models for the carbon terminated β-SiC(100)-c(2 × 2) surface structure is investigated through the use of ab initio calculations. The structural and electronic effect of hydrogen atoms bonded to carbon and/or silicon dimers is specifically considered and compared with the results for a clean surface model. The presence of adsorbed hydrogen atoms affects the atomic equilibrium positions, as well as electronic properties, of the atoms of the clean structure. These last properties are altered in different directions if the adsorption occurs in one or the other of the two investigated models. The changes in both structural and electronic properties were evaluated and compared with those of the clean surface. From our obtained results, a possible metallization, as a result of hydrogen adsorption, is theoretically postulated to occur in a similar way to what occurs with the silicon terminated β-SiC(100)(3 × 2) surface.
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Affiliation(s)
- Alcemira Conceição Oliveira
- Grupo de Física de Superfcies e Materiais, Instituto de Física, Universidade Federal da Bahia, Campus Universitário da Federação, 40210-340, Salvador, BA, Brazil
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23
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Moreira IDP, Wojdeł JC, Illas F, Chiesa M, Giamello E. Evidence of magnetic ordering of paramagnetic surface defects on partially hydroxylated MgO nanocrystals. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.07.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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D’angelo M, Enriquez H, Rodriguez N, Aristov VY, Soukiassian P, Tejeda A, Michel EG, Pedio M, Ottaviani C, Perfetti P. Interaction of atomic hydrogen with the β-SiC(100) 3×2 surface and subsurface. J Chem Phys 2007; 127:164716. [DOI: 10.1063/1.2799993] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Wang Y, Meyer B, Yin X, Kunat M, Langenberg D, Traeger F, Birkner A, Wöll C. Hydrogen induced metallicity on the ZnO(1010) surface. PHYSICAL REVIEW LETTERS 2005; 95:266104. [PMID: 16486375 DOI: 10.1103/physrevlett.95.266104] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Indexed: 05/06/2023]
Abstract
Exposure of the mixed-terminated surface to atomic hydrogen at room temperature is found to lead to drastic changes of the electrical properties. The insulator surface is found to become metallic. By employing several experimental techniques (electron energy loss spectroscopy, He-atom scattering, and scanning tunneling microscopy) together with ab initio electronic structure calculations we demonstrate that a low-temperature (1 x 1) phase with two H atoms in the unit cell transforms upon heating to another (1 x 1) phase with only one H atom per unit cell. The odd number of electrons added to the surface per unit cell gives rise to partially filled surface states and thus a metallization of the surface.
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Affiliation(s)
- Y Wang
- Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, Germany
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26
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Chang H, Wu J, Gu BL, Liu F, Duan W. Physical origin of hydrogen-adsorption-induced metallization of the SiC surface: n-type doping via formation of hydrogen bridge bond. PHYSICAL REVIEW LETTERS 2005; 95:196803. [PMID: 16384009 DOI: 10.1103/physrevlett.95.196803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2005] [Indexed: 05/05/2023]
Abstract
We perform first-principles calculations to explore the physical origin of hydrogen-induced semiconductor surface metallization observed in beta-SiC(001)-3 x 2 surface. We show that the surface metallization arises from a novel mechanism of n-type doping of surface band via formation of hydrogen bridge bonds (i.e., Si-H-Si complex). The hydrogen strengthens the weak Si-Si dimers in the subsurface by forming hydrogen bridge bonds, and donates electron to the surface conduction band.
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Affiliation(s)
- Hao Chang
- Department of Physics and Center for Advanced Study, Tsinghua University, Beijing 100084, People's Republic of China
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27
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Kanai Y, Cicero G, Selloni A, Car R, Galli G. A Theoretical Study of Biotin Chemisorption on Si−SiC(001) Surfaces. J Phys Chem B 2005; 109:13656-62. [PMID: 16852711 DOI: 10.1021/jp051360h] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biotin is a promising candidate for functionalization of semiconducting surfaces, given its strong, unmatched affinity to specific proteins such as streptavidin and avidin. Using density functional theory, we have carried out a theoretical investigation of the structural and electronic properties of biotin chemisorbed on a biocompatible substrate; in particular we have considered the clean and hydroxylated Si-SiC(001) surfaces. Our calculations show that, upon chemisorption, biotin retains the electronic properties responsible for its strong affinity to proteins. While the electronic states of the hydroxylated surface undergo negligible changes in the presence of the molecule, those of the clean surface are considerably affected.
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Affiliation(s)
- Yosuke Kanai
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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28
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Cicero G, Grossman JC, Catellani A, Galli G. Water at a Hydrophilic Solid Surface Probed by Ab initio Molecular Dynamics: Inhomogeneous Thin Layers of Dense Fluid. J Am Chem Soc 2005; 127:6830-5. [PMID: 15869306 DOI: 10.1021/ja042963u] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a microscopic model of the interface between liquid water and a hydrophilic, solid surface, as obtained from ab initio molecular dynamics simulations. In particular, we focused on the (100) surface of cubic SiC, a leading semiconductor candidate for biocompatible devices. Our results show that in the liquid in contact with the clean substrate, molecular dissociation occurs in a manner unexpectedly similar to that observed in the gas phase. After full hydroxylation takes place, the formation of a thin (approximately 3 A) interfacial layer is observed, which has higher density than bulk water and forms stable hydrogen bonds with the substrate. The presence of this thin layer points at rather weak effects on the structural properties of water induced by a one-dimensional confinement between approximately 1.3 nm hydrophilic substrates. In addition, our results show that the liquid does not uniformly wet the surface, but molecules preferably bind along directions parallel to the Si dimer rows.
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Affiliation(s)
- Giancarlo Cicero
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550, USA.
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29
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Di Felice R, Bertoni CM, Pignedoli CA, Catellani A. Hydrogen-induced surface metallization of beta-SiC(100)-(3x2) revisited by density functional theory calculations. PHYSICAL REVIEW LETTERS 2005; 94:116103. [PMID: 15903874 DOI: 10.1103/physrevlett.94.116103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2004] [Indexed: 05/02/2023]
Abstract
Recent experiments on the silicon terminated (3 x 2)-SiC(100) surface indicated an unexpected metallic character upon hydrogen adsorption. This effect was attributed to the bonding of hydrogen to a row of Si atoms and to the stabilization of a neighboring dangling bond row. Here, on the basis of density-functional calculations, we show that multiple-layer adsorption of H at the reconstructed surface is compatible with a different geometry: in addition to saturating the topmost Si dangling bonds, H atoms are adsorbed at rather unusual sites, i.e., stable bridge positions above third-layer Si dimers. The results thus suggest an alternative interpretation for the electronic structure of the metallic surface.
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Affiliation(s)
- R Di Felice
- INFM-S3 National Center on nanoStructures and bioSystems at Surfaces, Dipartimento di Fisica, Università di Modena e Reggio Emilia, Via Campi 213/A, 41100 Modena, Italy.
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30
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Cicero G, Catellani A, Galli G. Atomic control of water interaction with biocompatible surfaces: the case of SiC(001). PHYSICAL REVIEW LETTERS 2004; 93:016102. [PMID: 15323996 DOI: 10.1103/physrevlett.93.016102] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Indexed: 05/24/2023]
Abstract
The interaction of water with Si- and C- terminated beta-SiC(001) surfaces was investigated by means of ab initio molecular dynamics simulations. Irrespective of coverage, varied from 1/4 to 1 monolayer, we found that water dissociates on the Si-terminated surface, substantially modifying the clean surface reconstruction, while the C-terminated surface is nonreactive and hydrophobic. Based on our results, we propose that STM images and photoemission experiments may detect specific changes induced by water on both the structural and electronic properties of SiC(001) surfaces.
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Affiliation(s)
- Giancarlo Cicero
- INFM & Physics Department, Torino Polytechnic, C. Duca degli Abruzzi, 24, I-10129 Torino, Italy.
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Bermudez VM. Surface science: A metallic semiconductor surface. NATURE MATERIALS 2003; 2:218-219. [PMID: 12690391 DOI: 10.1038/nmat861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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