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Bhartia B, Jayaraman S, Troadec C, Madapusi SP, Puniredd SR. Grafting of Organophosphonic Acid Monolayers on Hydrogen-Terminated Silicon Surface and Secondary Functionalization in Supercritical Carbon Dioxide Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12063-12074. [PMID: 37581455 DOI: 10.1021/acs.langmuir.3c01278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The monolayer grafting on the oxide-free Si surface is challenging due to vulnerability of the surface against oxide formation in an ambient atmosphere. Most of the conventional studies focused on organic solvent-based chemistry and solvent and substrate interfaces, and residual solvents after the monolayer grafting play a key role in producing the highly stable monolayers. CO2 in its supercritical state (SCCO2) provides an elegant engineering solution for the problem faced as it can be used as inert processing environment and as carrier fluid for monolayer grafting taking up the role of organic solvents. In this work, monolayers of alkyl organophosphonic acids (OPAs) and functional OPAs were grafted on hydrogen-terminated oxide-free Si surfaces using the SCCO2 process. Grafted monolayers were physically and chemically characterized to verify the successful monolayer formation and determine the nature of the covalent binding configuration on the surface. To broaden the prospects of practical utility of the process and the OPA monolayer, the (3-bromopropyl)phosphonic acid (BPPA) monolayer was demonstrated to undergo secondary functionalization by terminal group substitution to convert the Br terminal group to the OH terminal group and secondary monolayer grafting to assemble 4-fluorothiophenol on top of the BPPA monolayer. The ability of monolayers to sustain secondary functionalization processing qualitatively hints toward ordered and stable monolayers of OPAs. The developed SCCO2 process in this work presents a single-step, green, and scalable method to graft the OPA monolayer on oxide-free Si which can employed in the future for monolayer doping, highly selective biochemical sensors, and targeted biological interactions.
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Affiliation(s)
- Bhavesh Bhartia
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore,4 Engineering Drive 4, Singapore 117585, Republic of Singapore
| | - Sundaramurthy Jayaraman
- YSQ International Pte Ltd, 401 Commonwealth Drive, #07-01, Singapore 149598, Republic of Singapore
| | - Cedric Troadec
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
| | - Srinivasan Palavedu Madapusi
- Department of Chemical Engineering, BITS Pilani, Dubai Campus, Dubai International Academic City, P.O. Box No. 345055, Dubai 500001, UAE
| | - Sreenivasa Reddy Puniredd
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos, #01-02, Singapore 138669, Republic of Singapore
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2
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Reimers JR, Yang J, Darwish N, Kosov DS. Silicon - single molecule - silicon circuits. Chem Sci 2021; 12:15870-15881. [PMID: 35024111 PMCID: PMC8672724 DOI: 10.1039/d1sc04943g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
In 2020, silicon - molecule - silicon junctions were fabricated and shown to be on average one third as conductive as traditional junctions made using gold electrodes, but in some instances to be even more conductive, and significantly 3 times more extendable and 5 times more mechanically stable. Herein, calculations are performed of single-molecule junction structure and conductivity pertaining to blinking and scanning-tunnelling-microscopy (STM) break junction (STMBJ) experiments performed using chemisorbed 1,6-hexanedithiol linkers. Some strikingly different characteristics are found compared to analogous junctions formed using the metals which, to date, have dominated the field of molecular electronics. In the STMBJ experiment, following retraction of the STM tip after collision with the substrate, unterminated silicon surface dangling bonds are predicted to remain after reaction of the fresh tips with the dithiol solute. These dangling bonds occupy the silicon band gap and are predicted to facilitate extraordinary single-molecule conductivity. Enhanced junction extendibility is attributed to junction flexibility and the translation of adsorbed molecules between silicon dangling bonds. The calculations investigate a range of junction atomic-structural models using density-functional-theory (DFT) calculations of structure, often explored at 300 K using molecular dynamics (MD) simulations. These are aided by DFT calculations of barriers for passivation reactions of the dangling bonds. Thermally averaged conductivities are then evaluated using non-equilibrium Green's function (NEGF) methods. Countless applications through electronics, nanotechnology, photonics, and sensing are envisaged for this technology.
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Affiliation(s)
- Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures and School of Physics, Shanghai University Shanghai 200444 China
- School of Mathematical and Physical Sciences, University of Technology Sydney NSW 2007 Australia
| | - Junhao Yang
- International Centre for Quantum and Molecular Structures and School of Physics, Shanghai University Shanghai 200444 China
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University Townsville QLD 4811 Australia
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3
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Uzoma PC, Wang Q, Zhang W, Gao N, Li J, Okonkwo PC, Liu F, Han EH. Anti-bacterial, icephobic, and corrosion protection potentials of superhydrophobic nanodiamond composite coating. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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4
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Yuan S, Wang X, Zhang H, Yuan S. Atomistic Insights into Oxidation of Chemical Passivated Silicon (100) Surface: Reactive Molecular Dynamic Simulations. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202000476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University Jinan Shandong 250100 China
| | - Xueyu Wang
- Key Lab of Colloid and Interface Chemistry, Shandong University Jinan Shandong 250100 China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University Jinan Shandong 250100 China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University Jinan Shandong 250100 China
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5
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Yuan S, Zhang H, Yuan S. Reactive molecular dynamics on the oxidation of passivated H-terminated Si (111) surface: 1-Alkynes vs 1-Alkenes. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125372] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Muthukumaran T, Philip J. A facile approach to synthesis of cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide for organic dye removal. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Danos L, Halcovitch NR, Wood B, Banks H, Coogan MP, Alderman N, Fang L, Dzurnak B, Markvart T. Silicon photosensitisation using molecular layers. Faraday Discuss 2020; 222:405-423. [PMID: 32115600 DOI: 10.1039/c9fd00095j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Silicon photosensitisation via energy transfer from molecular dye layers is a promising area of research for excitonic silicon photovoltaics. We present the synthesis and photophysical characterisation of vinyl and allyl terminated Si(111) surfaces decorated with perylene molecules. The functionalised silicon surfaces together with Langmuir-Blodgett (LB) films based on perylene derivatives were studied using a wide range of steady-state and time resolved spectroscopic techniques. Fluorescence lifetime quenching experiments performed on the perylene modified monolayers revealed energy transfer efficiencies to silicon of up to 90 per cent. We present a simple model to account for the near field interaction of a dipole emitter with the silicon surface and distinguish between the 'true' FRET region (<5 nm) and a different process, photon tunnelling, occurring for distances between 10-50 nm. The requirements for a future ultra-thin crystalline solar cell paradigm include efficient surface passivation and keeping a close distance between the emitter dipole and the surface. These are discussed in the context of existing limitations and questions raised about the finer details of the emitter-silicon interaction.
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Affiliation(s)
- Lefteris Danos
- Department of Chemistry, Energy Lancaster, Lancaster University, Lancaster, LA1 4YB, UK.
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8
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Gonçales VR, Lian J, Gautam S, Tilley RD, Gooding JJ. Functionalized Silicon Electrodes in Electrochemistry. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2020; 13:135-158. [PMID: 32289237 DOI: 10.1146/annurev-anchem-091619-092506] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Avoiding the growth of SiOx has been an enduring task for the use of silicon as an electrode material in dynamic electrochemistry. This is because electrochemical assays become unstable when the SiOx levels change during measurements. Moreover, the silicon electrode can be completely passivated for electron transfer if a thick layer of insulating SiOx grows on the surface. As such, the field of silicon electrochemistry was mainly developed by electron-transfer studies in nonaqueous electrolytes and by applications employing SiOx-passivated silicon-electrodes where no DC currents are required to cross the electrode/electrolyte interface. A solution to this challenge began by functionalizing Si-H electrodes with monolayers based on Si-O-Si linkages. These monolayers have proven very efficient to avoid SiOx formation but are not stable for a long-term operation in aqueous electrolytes due to hydrolysis. It was only with the development of self-assembled monolayers based on Si-C linkages that a reliable protection against SiOx formation was achieved, particularly with monolayers based on α,ω-dialkynes. This review discusses in detail how this surface chemistry achieves such protection, the electron-transfer behavior of these monolayer-modified silicon surfaces, and the new opportunities for electrochemical applications in aqueous solution.
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Affiliation(s)
- Vinicius R Gonçales
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia; ,
| | - Jiaxin Lian
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia; ,
| | - Shreedhar Gautam
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia; ,
| | - Richard D Tilley
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia; ,
| | - J Justin Gooding
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia; ,
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9
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Peiris CR, Ciampi S, Dief EM, Zhang J, Canfield PJ, Le Brun AP, Kosov DS, Reimers JR, Darwish N. Spontaneous S-Si bonding of alkanethiols to Si(111)-H: towards Si-molecule-Si circuits. Chem Sci 2020; 11:5246-5256. [PMID: 34122981 PMCID: PMC8159313 DOI: 10.1039/d0sc01073a] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report the synthesis of covalently linked self-assembled monolayers (SAMs) on silicon surfaces, using mild conditions, in a way that is compatible with silicon-electronics fabrication technologies. In molecular electronics, SAMs of functional molecules tethered to gold via sulfur linkages dominate, but these devices are not robust in design and not amenable to scalable manufacture. Whereas covalent bonding to silicon has long been recognized as an attractive alternative, only formation processes involving high temperature and/or pressure, strong chemicals, or irradiation are known. To make molecular devices on silicon under mild conditions with properties reminiscent of Au–S ones, we exploit the susceptibility of thiols to oxidation by dissolved O2, initiating free-radical polymerization mechanisms without causing oxidative damage to the surface. Without thiols present, dissolved O2 would normally oxidize the silicon and hence reaction conditions such as these have been strenuously avoided in the past. The surface coverage on Si(111)–H is measured to be very high, 75% of a full monolayer, with density-functional theory calculations used to profile spontaneous reaction mechanisms. The impact of the Si–S chemistry in single-molecule electronics is demonstrated using STM-junction approaches by forming Si–hexanedithiol–Si junctions. Si–S contacts result in single-molecule wires that are mechanically stable, with an average lifetime at room temperature of 2.7 s, which is five folds higher than that reported for conventional molecular junctions formed between gold electrodes. The enhanced “ON” lifetime of this single-molecule circuit enables previously inaccessible electrical measurements on single molecules. Spontaneously formed Si–S bonds enable monolayer and single-molecule Si–molecule–Si circuits.![]()
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Affiliation(s)
- Chandramalika R Peiris
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Essam M Dief
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Jinyang Zhang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Peter J Canfield
- International Centre for Quantum and Molecular Structures, School of Physics, Shanghai University Shanghai 200444 China.,School of Chemistry, The University of Sydney NSW 2006 Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization (ANSTO) Lucas Heights NSW 2234 Australia
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University Townsville QLD 4811 Australia
| | - Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures, School of Physics, Shanghai University Shanghai 200444 China.,School of Mathematical and Physical Sciences, University of Technology Sydney NSW 2007 Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
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10
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Bhattacharyya D, Montenegro A, Plymale NT, Dutta C, Lewis NS, Benderskii AV. Vibrational Sum Frequency Generation Spectroscopy Measurement of the Rotational Barrier of Methyl Groups on Methyl-Terminated Silicon(111) Surfaces. J Phys Chem Lett 2019; 10:5434-5439. [PMID: 31442376 DOI: 10.1021/acs.jpclett.9b01487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The methyl-terminated Si(111) surface possesses a 3-fold in-plane symmetry, with the methyl groups oriented perpendicular to the substrate. The propeller-like rotation of the methyl groups is hindered at room temperature and proceeds via 120° jumps between three isoenergetic minima in registry with the crystalline Si substrate. We have used line-shape analysis of polarization-selected vibrational sum frequency generation spectroscopy to determine the rotational relaxation rate of the surface methyl groups and have measured the temperature dependence of the relaxation rate between 20 and 120 °C. By fitting the measured rate to an Arrhenius dependence, we extracted an activation energy (the rotational barrier) of 830 ± 360 cm-1 and an attempt frequency of (2.9 ± 4.2) × 1013 s-1 for the methyl rotation process. Comparison with the harmonic frequency of a methyl group in a 3-fold cosine potential suggests that the hindered rotation occurs via uncorrelated jumps of single methyl groups rather than concerted gear-like rotation.
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Affiliation(s)
- Dhritiman Bhattacharyya
- Department of Chemistry , University of Southern California , Los Angeles , California 90089-0482 , United States
| | - Angelo Montenegro
- Department of Chemistry , University of Southern California , Los Angeles , California 90089-0482 , United States
| | - Noah T Plymale
- Division of Chemistry and Chemical Engineering, and Beckman Institute , California Institute of Technology , Pasadena , California 91125 , United States
| | - Chayan Dutta
- Department of Chemistry , University of Southern California , Los Angeles , California 90089-0482 , United States
| | - Nathan S Lewis
- Division of Chemistry and Chemical Engineering, and Beckman Institute , California Institute of Technology , Pasadena , California 91125 , United States
| | - Alexander V Benderskii
- Department of Chemistry , University of Southern California , Los Angeles , California 90089-0482 , United States
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11
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Chatgilialoglu C, Ferreri C, Landais Y, Timokhin VI. Thirty Years of (TMS)3SiH: A Milestone in Radical-Based Synthetic Chemistry. Chem Rev 2018; 118:6516-6572. [DOI: 10.1021/acs.chemrev.8b00109] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Carla Ferreri
- ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy
| | - Yannick Landais
- University of Bordeaux, Institute of Molecular Sciences, UMR-CNRS 5255, 351 cours de la libération, 33405 Talence Cedex, France
| | - Vitaliy I. Timokhin
- Department of Biochemistry, University of Wisconsin-Madison, 1552 University Avenue, Madison, Wisconsin 53726, United States
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12
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Pujari S, Filippov AD, Gangarapu S, Zuilhof H. High-Density Modification of H-Terminated Si(111) Surfaces Using Short-Chain Alkynes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:14599-14607. [PMID: 29240433 PMCID: PMC6150740 DOI: 10.1021/acs.langmuir.7b03683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/29/2017] [Indexed: 05/31/2023]
Abstract
H-Si(111)-terminated surfaces were alkenylated via two routes: through a novel one-step gas-phase hydrosilylation reaction with short alkynes (C3 to C6) and for comparison via a two-step chlorination and Grignard alkenylation process. All modified surfaces were characterized by static water contact angles and X-ray photoelectron spectroscopy (XPS). Propenyl- and butenyl-coated Si(111) surfaces display a significantly higher packing density than conventional C10-C18 alkyne-derived monolayers, showing the potential of this approach. In addition, propyne chemisorption proceeds via either of two approaches: the standard hydrosilylation at the terminal carbon (lin) at temperatures above 90 °C and an unprecedented reaction at the second carbon (iso) at temperatures below 90 °C. Molecular modeling revealed that the packing energy of a monolayer bonded at the second carbon is significantly more favorable, which drives iso-attachment, with a dense packing of surface-bound iso-propenyl chains at 40% surface coverage, in line with the experiments at <90 °C. The highest density monolayers are obtained at 130 °C and show a linear attachment of 1-propenyl chains with 92% surface coverage.
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Affiliation(s)
- Sidharam
P. Pujari
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Alexei D. Filippov
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Satesh Gangarapu
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Han Zuilhof
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- School
of Pharmaceutical Sciences and Technology, Tianjin University, 92 Weijin Road, Tianjin, People’s
Republic of China
- Department
of Chemical and Materials Engineering, King
Abdulaziz University, Jeddah, Saudi Arabia
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13
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Soria FA, Zhang W, van Duin ACT, Patrito EM. Thermal Stability of Organic Monolayers Grafted to Si(111): Insights from ReaxFF Reactive Molecular Dynamics Simulations. ACS APPLIED MATERIALS & INTERFACES 2017; 9:30969-30981. [PMID: 28810729 DOI: 10.1021/acsami.7b05444] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We used the ReaxFF reactive molecular dynamics simulations to investigate the chemical mechanisms and kinetics of thermal decomposition processes of silicon surfaces grafted with different organic molecules via Si-C bonds at atomistic level. In this work, we considered the Si(111) surface grafted with n-alkyl (ethyl, propyl, pentyl, and decyl) layers in 50% coverage and, Si-CH3, Si-CCCH3 and Si-CHCHCH3 layers in full coverage. Si radicals primarily formed by the homolytic cleavage of Si-C bonds play a key role in the dehydrogenation processes that lead to the decomposition of the monolayers. Contrary to commonly proposed mechanisms that only involve a single Si atom center, we found that the main decomposition pathways require two Si lattice atoms to proceed. The ability of surface silyl radicals to dehydrogenate the organic molecules depends on the flexibility of the carbon backbones of the organic molecules as well as on the C-H bond strength. The dehydrogenation of n-alkyl chains mainly involves the H atoms of the β-carbon (leading to 1-alkene desorption). However, as the surface coverage decreases, the flexibility of the alkyl chains allows for the dehydrogenation of any methylene group and even the terminal methyl group of the long decyl layer. On the contrary, the rigid carbon backbone of the Si-CCCH3 and Si-CHCHCH3 moieties hinders the dehydrogenation of the terminal methyl group, which confers these layers a higher thermal stability. For all layers, the surface ends up mostly hydrogenated as Si-C bonds break and new Si-H bonds are formed during the dehydrogenation reactions.
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Affiliation(s)
| | - Weiwei Zhang
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Adri C T van Duin
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University , University Park, Pennsylvania 16802, United States
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14
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Li X, Ma W, Shestopalov AA. Vapor-Phase Carbenylation of Hard and Soft Material Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11386-11394. [PMID: 27759398 DOI: 10.1021/acs.langmuir.6b02471] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study describes the formation of functional organic monolayers on hard and soft interfaces via a vapor-phase carbene insertion into Si-H and C-H bonds. We demonstrate that functional diazirine molecules can be used to form monomolecular coatings on silicon, silicon nitride, and urethane-acrylate polymers under mild vacuum conditions and exposure to UV light. We investigate the molecular coverage and the long-term stability of the resulting monolayers in air, isopropanol, and water. Our results suggest that vapor-phase carbenylation can be used as a complementary technology to the traditional self-assembly, permitting functionalization of various passivated substrates with stable and functional molecular coatings under mild and scalable conditions.
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Affiliation(s)
- Xunzhi Li
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Wenchuan Ma
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Alexander A Shestopalov
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
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15
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Bhartia B, Puniredd SR, Jayaraman S, Gandhimathi C, Sharma M, Kuo YC, Chen CH, Reddy VJ, Troadec C, Srinivasan MP. Highly Stable Bonding of Thiol Monolayers to Hydrogen-Terminated Si via Supercritical Carbon Dioxide: Toward a Super Hydrophobic and Bioresistant Surface. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24933-24945. [PMID: 27540859 DOI: 10.1021/acsami.6b06018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Oxide-free silicon chemistry has been widely studied using wet-chemistry methods, but for emerging applications such as molecular electronics on silicon, nanowire-based sensors, and biochips, these methods may not be suitable as they can give rise to defects due to surface contamination, residual solvents, which in turn can affect the grafted monolayer devices for practical applications. Therefore, there is a need for a cleaner, reproducible, scalable, and environmentally benign monolayer grafting process. In this work, monolayers of alkylthiols were deposited on oxide-free semiconductor surfaces using supercritical carbon dioxide (SCCO2) as a carrier fluid owing to its favorable physical properties. The identity of grafted monolayers was monitored with Fourier transform infrared (FTIR) spectroscopy, high-resolution X-ray photoelectron spectroscopy (HRXPS), XPS, atomic force microscopy (AFM), contact angle measurements, and ellipsometry. Monolayers on oxide-free silicon were able to passivate the surface for more than 50 days (10 times than the conventional methods) without any oxide formation in ambient atmosphere. Application of the SCCO2 process was further extended by depositing alkylthiol monolayers on fragile and brittle 1D silicon nanowires (SiNWs) and 2D germanium substrates. With the recent interest in SiNWs for biological applications, the thiol-passivated oxide-free silicon nanowire surfaces were also studied for their biological response. Alkylthiol-functionalized SiNWs showed a significant decrease in cell proliferation owing to their superhydrophobicity combined with the rough surface morphology. Furthermore, tribological studies showed a sharp decrease in the coefficient of friction, which was found to be dependent on the alkyl chain length and surface bond. These studies can be used for the development of cost-effective and highly stable monolayers for practical applications such as solar cells, biosensors, molecular electronics, micro- and nano- electromechanical systems, antifouling agents, and drug delivery.
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Affiliation(s)
- Bhavesh Bhartia
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, #08-32, Singapore 138634
- Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585
| | - Sreenivasa Reddy Puniredd
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, #08-32, Singapore 138634
| | - Sundaramurthy Jayaraman
- Environmental and Water Technology Centre of Innovation, Ngee Ann Polytechnic , 535 Clementi Road, Singapore 599489
| | - Chinnasamy Gandhimathi
- Centre for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, National University of Singapore , Singapore 117576
| | - Mohit Sharma
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, #08-32, Singapore 138634
| | - Yen-Chien Kuo
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chia-Hao Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Venugopal Jayarama Reddy
- Centre for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, National University of Singapore , Singapore 117576
| | - Cedric Troadec
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, #08-32, Singapore 138634
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16
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Tao Y, Hauert R, Degen CL. Exclusively Gas-Phase Passivation of Native Oxide-Free Silicon(100) and Silicon(111) Surfaces. ACS APPLIED MATERIALS & INTERFACES 2016; 8:13157-13165. [PMID: 27153212 DOI: 10.1021/acsami.6b03326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Reactions in the gas phase are of primary technological importance for applications in nano- and microfabrication technology and in the semiconductor industry. We present exclusively gas-phase protocols to chemically passivate oxide-free Si(111) and Si(100) surfaces with short-chain alkynes. The resulting surfaces showed equal or better oxidation resistance than most existing liquid-phase-derived surfaces and rivaled the outstanding stability of a full-coverage Si(111)-propenyl surface.1,2 The most stable surface (Si(111)-ethenyl) grew one-fifth of a monolayer of oxide (0.04 nm) after 1 month of air exposure. We monitored the regrowth of oxides on passivated Si(111) and Si(100) surfaces by X-ray photoelectron spectroscopy (XPS) and observed a significant crystal-orientation dependence of initial rates when total oxide thickness was below approximately one monolayer (0.2 nm). This difference was correlated with the desorption kinetics of residual surface Si-F bonds formed during HF treatment. We discuss applications of the technology and suggest future directions for process optimization.
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Affiliation(s)
- Ye Tao
- Department of Physics, ETH Zürich , 8093 Zürich, Switzerland
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Roland Hauert
- Empa, Swiss Federal Laboratories of Materials Science and Technology , 8600 Dübendorf, Switzerland
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17
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Varol HS, Sánchez MA, Lu H, Baio JE, Malm C, Encinas N, Mermet-Guyennet MRB, Martzel N, Bonn D, Bonn M, Weidner T, Backus EHG, Parekh SH. Multiscale Effects of Interfacial Polymer Confinement in Silica Nanocomposites. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01111] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
| | | | | | - Joe E. Baio
- School of
Chemical,
Biological and Environmental Engineering, Oregon State University, Corvalis, Oregon 97333, United States
| | | | | | | | - Nicolas Martzel
- Manufacture française
des pneumatiques MICHELIN, Site de Ladoux, 23 place Carmes Déchaux, 63040 Clermont-Ferrand, France
| | - Daniel Bonn
- Institute
of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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18
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Guan B, Siampour H, Fan Z, Wang S, Kong XY, Mesli A, Zhang J, Dan Y. Nanoscale Nitrogen Doping in Silicon by Self-Assembled Monolayers. Sci Rep 2015; 5:12641. [PMID: 26227342 PMCID: PMC4521158 DOI: 10.1038/srep12641] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 07/06/2015] [Indexed: 11/09/2022] Open
Abstract
This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10−15 cm2 s−1, 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen dopants exhibit electrical activity. The analysis of Hall effect data at low temperatures indicates that the donor energy level for nitrogen dopants is located at 189 meV below the conduction band, consistent with the literature value.
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Affiliation(s)
- Bin Guan
- University of Michigan - Shanghai Jiao Tong University Joint Institute
| | | | - Zhao Fan
- University of Michigan - Shanghai Jiao Tong University Joint Institute
| | - Shun Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy
| | - Xiang Yang Kong
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200040, China
| | - Abdelmadjid Mesli
- Institut Matériaux Microélectronique Nanosciences de Provence, UMR 6242 CNRS, Université Aix-Marseille, 13397 Marseille Cedex 20, France
| | - Jian Zhang
- Faculty of Medicine, Shanghai Jiao Tong University, Shanghai, 200040, China
| | - Yaping Dan
- University of Michigan - Shanghai Jiao Tong University Joint Institute
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19
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Bhartia B, Bacher N, Jayaraman S, Khatib S, Song J, Guo S, Troadec C, Puniredd SR, Srinivasan MP, Haick H. Application of Organophosphonic Acids by One-Step Supercritical CO2 on 1D and 2D Semiconductors: Toward Enhanced Electrical and Sensing Performances. ACS APPLIED MATERIALS & INTERFACES 2015; 7:14885-14895. [PMID: 26087766 DOI: 10.1021/acsami.5b03597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Formation of dense monolayers with proven atmospheric stability using simple fabrication conditions remains a major challenge for potential applications such as (bio)sensors, solar cells, surfaces for growth of biological cells, and molecular, organic, and plastic electronics. Here, we demonstrate a single-step modification of organophosphonic acids (OPA) on 1D and 2D structures using supercritical carbon dioxide (SCCO2) as a processing medium, with high stability and significantly shorter processing times than those obtained by the conventional physisorption-chemisorption method (2.5 h vs 48-60 h).The advantages of this approach in terms of stability and atmospheric resistivity are demonstrated on various 2D materials, such as indium-tin-oxide (ITO) and 2D Si surfaces. The advantage of the reported approach on electronic and sensing devices is demonstrated by Si nanowire field effect transistors (SiNW FETs), which have shown a few orders of magnitude higher electrical and sensing performances, compared with devices obtained by conventional approaches. The compatibility of the reported approach with various materials and its simple implementation with a single reactor makes it easily scalable for various applications.
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Affiliation(s)
- Bhavesh Bhartia
- ‡Department of Chemical and Biomolecular Engineering, National University of Singapore,4 Engineering Drive 4, Singapore 117585, Singapore
| | - Nadav Bacher
- §The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Sundaramurthy Jayaraman
- ⊥Environmental and Water Technology Centre of Innovation, Ngee Ann Polytechnic, 535 Clementi Rd, Singapore599489, Singapore
| | - Salam Khatib
- §The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Jing Song
- ∥Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
| | - Shifeng Guo
- ∥Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
| | - Cedric Troadec
- ∥Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
| | - Sreenivasa Reddy Puniredd
- ∥Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
| | - Madapusi Palavedu Srinivasan
- ‡Department of Chemical and Biomolecular Engineering, National University of Singapore,4 Engineering Drive 4, Singapore 117585, Singapore
| | - Hossam Haick
- §The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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20
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Halpern JM, Wang B, Haick H. Controlling the Sensing Properties of Silicon Nanowires via the Bonds Nearest to the Silicon Nanowire Surface. ACS APPLIED MATERIALS & INTERFACES 2015; 7:11315-11321. [PMID: 25961907 DOI: 10.1021/acsami.5b01721] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Controlling the sensing properties of a silicon nanowire field effect transistor is dependent on the surface chemistry of the silicon nanowire. A standard silicon nanowire has a passive oxide layer (native oxide), which has trap states that cause sensing inaccuracies and desensitize the surface to nonpolar molecules. In this paper, we successfully modified the silicon nanowire surface with different nonoxide C3 alkyl groups, specifically, propyl (Si-CH2-CH2-CH3), propenyl (Si-CH═CH-CH3), and propynyl (Si-C≡C-CH3) modifications. The effect of the near surface bond on the sensor sensitivity and stability was explored by comparing three C3 surface modifications. A reduction of trap-states led to greater sensor stability and accuracy. The propenyl-modified sensor was consistently the most stable and sensitive sensor, among the applied sensors. The propenyl- and propynyl-modified sensors consistently performed with the best accuracy in identifying specific analytes with similar polarity or similar molecular weights. A combination of features from different sensing surfaces led to the best rubric for specific analytes identification. These results indicate that nonoxide sensor surfaces are useful in identifying specific analytes and that a combination of sensors with different surfaces in a cross-reactive array can lead to specific analytes detection.
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Affiliation(s)
- Jeffrey Mark Halpern
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Bin Wang
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Hossam Haick
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
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21
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Liu X, Cheng H, Zhao T, Zhang C. Facile routes of manufacturing silicon quantum dots on a silicon wafer and their surface activation by esters of N-hydroxysuccinimide. J Colloid Interface Sci 2014; 426:117-23. [DOI: 10.1016/j.jcis.2014.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 03/12/2014] [Accepted: 04/02/2014] [Indexed: 11/16/2022]
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22
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Bhairamadgi NS, Pujari SP, Trovela FG, Debrassi A, Khamis AA, Alonso JM, Al Zahrani AA, Wennekes T, Al-Turaif HA, van Rijn C, Alhamed YA, Zuilhof H. Hydrolytic and thermal stability of organic monolayers on various inorganic substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5829-5839. [PMID: 24825533 DOI: 10.1021/la500533f] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A comparative study is presented of the hydrolytic and thermal stability of 24 different kinds of monolayers on Si(111), Si(100), SiC, SiN, SiO2, CrN, ITO, PAO, Au, and stainless steel surfaces. These surfaces were modified utilizing appropriate organic compounds having a constant alkyl chain length (C18), but with different surface-reactive groups, such as 1-octadecene, 1-octadecyne, 1-octadecyltrichlorosilane, 1-octadecanethiol, 1-octadecylamine and 1-octadecylphosphonic acid. The hydrolytic stability of obtained monolayers was systematically investigated in triplicate in constantly flowing aqueous media at room temperature in acidic (pH 3), basic (pH 11), phosphate buffer saline (PBS) and deionized water (neutral conditions), for a period of 1 day, 7 days, and 30 days, yielding 1152 data points for the hydrolytic stability. The hydrolytic stability was monitored by static contact angle measurements and X-ray photoelectron spectroscopy (XPS). The covalently bound alkyne monolayers on Si(111), Si(100), and SiC were shown to be among the most stable monolayers under acidic and neutral conditions. Additionally, the thermal stability of 14 different monolayers was studied in vacuum using XPS at elevated temperatures (25-600 °C). Similar to the hydrolytic stability, the covalently bound both alkyne and alkene monolayers on Si(111), Si(100) and SiC started to degrade from temperatures above 260 °C, whereas on oxide surfaces (e.g., PAO) phosphonate monolayers even displayed thermal stability up to ∼500 °C.
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Affiliation(s)
- Nagendra S Bhairamadgi
- Laboratory of Organic Chemistry, Wageningen University and Research Center , Dreijenplein 8, 6703 HB Wageningen, The Netherlands
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23
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Liu W, Sharp ID, Tilley TD. Multifunctional silicon surfaces: reaction of dichlorocarbene generated from Seyferth reagent with hydrogen-terminated silicon (111) surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:172-178. [PMID: 24328351 DOI: 10.1021/la403789a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering ∼25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.
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Affiliation(s)
- Wenjun Liu
- Joint Center for Artificial Photosynthesis, ‡Materials Sciences Division, §Physical Biosciences Division, and ∥Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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24
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Michaels P, Alam MT, Ciampi S, Rouesnel W, Parker SG, Choudhury MH, Gooding JJ. A robust DNA interface on a silicon electrode. Chem Commun (Camb) 2014; 50:7878-80. [DOI: 10.1039/c4cc03418j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Schematic of a DNA sensing interface formed on oxide-free silicon electrodes that both resist nonspecific adsorption of DNA and maintains stable electrical properties in biological media.
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Affiliation(s)
- Pauline Michaels
- School of Chemistry
- The University of New South Wales
- Sydney, Australia
| | | | - Simone Ciampi
- School of Chemistry
- The University of New South Wales
- Sydney, Australia
| | - William Rouesnel
- School of Chemistry
- The University of New South Wales
- Sydney, Australia
| | - Stephen G. Parker
- School of Chemistry
- The University of New South Wales
- Sydney, Australia
- Australian Centre for NanoMedicine
- The University of New South Wales
| | | | - J. Justin Gooding
- School of Chemistry
- The University of New South Wales
- Sydney, Australia
- Australian Centre for NanoMedicine
- The University of New South Wales
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25
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Yaffe O, Ely T, Har-Lavan R, Egger D, Johnston S, Cohen H, Kronik L, Vilan A, Cahen D. Effect of Molecule-Surface Reaction Mechanism on the Electronic Characteristics and Photovoltaic Performance of Molecularly Modified Si. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2013; 117:22351-22361. [PMID: 24205409 PMCID: PMC3814651 DOI: 10.1021/jp4027755] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/27/2013] [Indexed: 06/02/2023]
Abstract
We report on the passivation properties of molecularly modified, oxide-free Si(111) surfaces. The reaction of 1-alcohol with the H-passivated Si(111) surface can follow two possible paths, nucleophilic substitution (SN) and radical chain reaction (RCR), depending on adsorption conditions. Moderate heating leads to the SN reaction, whereas with UV irradiation RCR dominates, with SN as a secondary path. We show that the site-sensitive SN reaction leads to better electrical passivation, as indicated by smaller surface band bending and a longer lifetime of minority carriers. However, the surface-insensitive RCR reaction leads to more dense monolayers and, therefore, to much better chemical stability, with lasting protection of the Si surface against oxidation. Thus, our study reveals an inherent dissonance between electrical and chemical passivation. Alkoxy monolayers, formed under UV irradiation, benefit, though, from both chemical and electronic passivation because under these conditions both SN and RCR occur. This is reflected in longer minority carrier lifetimes, lower reverse currents in the dark, and improved photovoltaic performance, over what is obtained if only one of the mechanisms operates. These results show how chemical kinetics and reaction paths impact electronic properties at the device level. It further suggests an approach for effective passivation of other semiconductors.
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Affiliation(s)
- Omer Yaffe
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Tal Ely
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Rotem Har-Lavan
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - David
A. Egger
- Institute of Solid State Physics, Graz University of Technology, A-8010 Graz, Austria
| | - Steve Johnston
- National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Hagai Cohen
- Department of Chemical Research
Support, Weizmann Institute of Science,
Rehovoth 76100, Israel
| | - Leeor Kronik
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Ayelet Vilan
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - David Cahen
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
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26
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Collins G, O'Dwyer C, Morris M, Holmes JD. Palladium-catalyzed coupling reactions for the functionalization of Si surfaces: superior stability of alkenyl monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11950-11958. [PMID: 23968278 DOI: 10.1021/la402480f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Palladium-catalyzed Suzuki, Heck, and Sonogashira coupling reactions were studied as reaction protocols for organic modification of Si surfaces. These synthetically useful protocols allow for surface modification of alkene, alkyne, and halide terminated surfaces. Surface oxidation and metal contamination were assessed by X-ray photoelectron spectroscopy. The nature of the primary passivation layer was an important factor in the oxidation resistance of the Si surface during the secondary functionalization. Specifically, the use of alkynes as the primary functionalization layer gave superior stability compared to alkene analogues. The ability to utilize Pd-catalyzed coupling chemistries on Si surfaces opens great versatility for potential molecular and nanoscale electronics and sensing/biosensing applications.
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Affiliation(s)
- Gillian Collins
- Department of Chemistry and the Tyndall National Institute, University College Cork , Cork, Ireland
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27
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Wang B, Haick H. Effect of chain length on the sensing of volatile organic compounds by means of silicon nanowires. ACS APPLIED MATERIALS & INTERFACES 2013; 5:5748-56. [PMID: 23725353 DOI: 10.1021/am401265z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Molecularly modified silicon nanowire field effect transistors (SiNW FETs) are starting to appear as promising devices for sensing various volatile organic compounds (VOCs). Understanding the connection between the molecular layer structure attached to the SiNWs and VOCs is essential for the design of high performance sensors. Here, we explore the chain length influence of molecular layers on the sensing performance to polar and nonpolar VOCs. SiNW FETs were functionalized with molecular layers that have similar end (methyl) group and amide bridge bond, but differ in their alkyl chain lengths. The resulting devices were then exposed to polar and nonpolar VOCs in various concentrations. Our results showed that the sensing response to changing the threshold voltage (ΔVth) and changing the relative hole mobility (Δμh/μh-a) have a proportional relationship to the VOC concentration. On exposure to a specific VOC concentration, ΔVth response increased with the chain length of the molecular modification. In contrast, Δμh/μh-a did not exhibit any obvious reliance on the chain length of the molecular layer. Analysis of the responses with an electrostatic-based model suggests that the sensor response in ΔVth is dependent on the VOC concentration, VOC vapor pressure, VOC-molecular layer binding energy, and VOC adsorption-induced dipole moment changes of molecular layer.
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Affiliation(s)
- Bin Wang
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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28
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Zhang F, Liu D, Zhang Y, Wei H, Song T, Sun B. Methyl/allyl monolayer on silicon: efficient surface passivation for silicon-conjugated polymer hybrid solar cell. ACS APPLIED MATERIALS & INTERFACES 2013; 5:4678-84. [PMID: 23635411 DOI: 10.1021/am302893r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We demonstrate a hybrid Schottky junction solar cell based on methyl/allyl groups terminated silicon nanowire arrays (SiNWs) and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) with a power conversion efficiency (PCE) of 10.2%. The methyl/allyl organic monolayer on silicon can act as an excellent passivation layer for suppressing surface charge recombination, which is characterized by grazing angle attenuated total reflectance Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements. The transient and steady electric output characteristics measurements indicate that the density of trap states of SiNWs are dramatically suppressed by methyl/allyl surface modification. In addition, the device based on methyl/allyl passivated SiNWs exhibits improved stable electrical output over those based on either methyl or allyl passivated ones. The improved PCE and good stability of the device are ascribed to efficient functionalization of the SiNW surface.
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Affiliation(s)
- Fute Zhang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, China
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29
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Puniredd SR, Jayaraman S, Yeong SH, Troadec C, Srinivasan MP. Stable Organic Monolayers on Oxide-Free Silicon/Germanium in a Supercritical Medium: A New Route to Molecular Electronics. J Phys Chem Lett 2013; 4:1397-1403. [PMID: 26282291 DOI: 10.1021/jz4005416] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Oxide-free Si and Ge surfaces have been passivated and modified with organic molecules by forming covalent bonds between the surfaces and reactive end groups of linear alkanes and aromatic species using single-step deposition in supercritical carbon dioxide (SCCO2). The process is suitable for large-scale manufacturing due to short processing times, simplicity, and high resistance to oxidation. It also allows the formation of monolayers with varying reactive terminal groups, thus enabling formation of nanostructures engineered at the molecular level. Ballistic electron emission microscopy (BEEM) spectra performed on the organic monolayer on oxide-free silicon capped by a thin gold layer reveals for the first time an increase in transmission of the ballistic current through the interface of up to three times compared to a control device, in contrast to similar studies reported in the literature suggestive of oxide-free passivation in SCCO2. The SCCO2 process combined with the preliminary BEEM results opens up new avenues for interface engineering, leading to molecular electronic devices.
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Affiliation(s)
- Sreenivasa Reddy Puniredd
- †Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576
- ‡Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602
| | - Sundaramurthy Jayaraman
- †Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576
| | - Sai Hooi Yeong
- †Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576
| | - Cedric Troadec
- ‡Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602
| | - M P Srinivasan
- †Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576
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30
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Ciampi S, James M, Choudhury MH, Darwish NA, Gooding JJ. The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes. Phys Chem Chem Phys 2013; 15:9879-90. [DOI: 10.1039/c3cp50355k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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32
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Pujari SP, Spruijt E, Cohen Stuart MA, van Rijn CJM, Paulusse JMJ, Zuilhof H. Ultralow adhesion and friction of fluoro-hydro alkyne-derived self-assembled monolayers on H-terminated Si(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:17690-17700. [PMID: 23234602 DOI: 10.1021/la303893u] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
New fluorine-containing terminal alkynes were synthesized and self-assembled onto Si(111) substrates to obtain fluorine-containing organic monolayers. The monolayers were analyzed in detail by ellipsometry, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), static water contact angle measurements (CA), and atomic force microscopy (AFM). The SAMs exhibit excellent hydrophobicity, with static water contact angles of up to 119° and low critical surface tensions of 5-20 mN/m depending on the number of F atoms per molecule. IRRAS confirmed the formation of highly ordered monolayers, as indicated by the antisymmetric and symmetric stretching vibrations of the CH(2) moieties at 2918-2920 and 2850-2851 cm(-1), respectively. Upon increasing the number of fluorine atoms in the alkyne chains from 0 to 17, the adhesion of bare silica probes to the SAMs in air decreases from 11.6 ± 0.20 mJ/m(2) for fluorine-free (F0) alkyne monolayers to as low as 3.2 ± 0.03 mJ/m(2) for a heptadecafluoro-hexadecyne (F17)-based monolayer. Likewise, the friction coefficient decreases from 5.7 × 10(-2) to 1.2 × 10(-2). The combination of high ordering, excellent hydrophobicity, low adhesion, and low friction makes these fluoro-hydro alkyne-derived monolayers highly promising candidates for use in high-performance microelectronic devices.
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Affiliation(s)
- Sidharam P Pujari
- Laboratory of Organic Chemistry, Wageningen University, Wageningen, The Netherlands
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Li Y, Calder S, Yaffe O, Cahen D, Haick H, Kronik L, Zuilhof H. Hybrids of organic molecules and flat, oxide-free silicon: high-density monolayers, electronic properties, and functionalization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9920-9929. [PMID: 22587009 DOI: 10.1021/la3010568] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Since the first report of Si-C bound organic monolayers on oxide-free Si almost two decades ago, a substantial amount of research has focused on studying the fundamental mechanical and electronic properties of these Si/molecule surfaces and interfaces. This feature article covers three closely related topics, including recent advances in achieving high-density organic monolayers (i.e., atomic coverage >55%) on oxide-free Si(111) substrates, an overview of progress in the fundamental understanding of the energetics and electronic properties of hybrid Si/molecule systems, and a brief summary of recent examples of subsequent functionalization on these high-density monolayers, which can significantly expand the range of applicability. Taken together, these topics provide an overview of the present status of this active area of research.
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Affiliation(s)
- Yan Li
- Laboratory of Organic Chemistry, Wageningen University, Wageningen, The Netherlands
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34
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Paska Y, Haick H. Interactive effect of hysteresis and surface chemistry on gated silicon nanowire gas sensors. ACS APPLIED MATERIALS & INTERFACES 2012; 4:2604-2617. [PMID: 22524252 DOI: 10.1021/am300288z] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Gated silicon nanowire gas sensors have emerged as promising devices for chemical and biological sensing applications. Nevertheless, the performance of these devices is usually accompanied by a "hysteresis" phenomenon that limits their performance under real-world conditions. In this paper, we use a series of systematically changed trichlorosilane-based organic monolayers to study the interactive effect of hysteresis and surface chemistry on gated silicon nanowire gas sensors. The results show that the density of the exposed or unpassivated Si-OH groups (trap states) on the silicon nanowire surface play by far a crucial effect on the hysteresis characteristics of the gated silicon nanowire sensors, relative to the effect of hydrophobicity or molecular density of the organic monolayer. Based on these findings, we provide a tentative model-based understanding of (i) the relation between the adsorbed organic molecules, the hysteresis, and the related fundamental parameters of gated silicon nanowire characteristics and of (ii) the relation between the hysteresis drift and possible screening effect on gated silicon nanowire gas sensors upon exposure to different analytes at real-world conditions. The findings reported in this paper could be considered as a launching pad for extending the use of the gated silicon nanowire gas sensors for discriminations between polar and nonpolar analytes in complex, real-world gas mixtures.
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Affiliation(s)
- Yair Paska
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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35
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Alderman N, Danos L, Grossel MC, Markvart T. Large surface photovoltages observed at methyl-terminated silicon surfaces synthesised through a two-step chlorination-alkylation method. RSC Adv 2012. [DOI: 10.1039/c2ra20465g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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36
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Ciampi S, Guan B, Darwish NA, Zhu Y, Reece PJ, Justin Gooding J. A multimodal optical and electrochemical device for monitoring surface reactions: redox active surfaces in porous silicon Rugate filters. Phys Chem Chem Phys 2012; 14:16433-9. [DOI: 10.1039/c2cp43461j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Bashouti MY, Sardashti K, Ristein J, Christiansen SH. Early stages of oxide growth in H-terminated silicon nanowires: determination of kinetic behavior and activation energy. Phys Chem Chem Phys 2012; 14:11877-81. [DOI: 10.1039/c2cp41709j] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Ciampi S, James M, Le Saux G, Gaus K, Justin Gooding J. Electrochemical “Switching” of Si(100) Modular Assemblies. J Am Chem Soc 2011; 134:844-7. [DOI: 10.1021/ja210048x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Simone Ciampi
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052,
Australia
| | - Michael James
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052,
Australia
- Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Guillaume Le Saux
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052,
Australia
| | - Katharina Gaus
- Centre for Vascular Research, The University of New South Wales, Sydney, NSW 2052,
Australia
| | - J. Justin Gooding
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052,
Australia
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39
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James M, Ciampi S, Darwish TA, Hanley TL, Sylvester SO, Gooding JJ. Nanoscale water condensation on click-functionalized self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10753-10762. [PMID: 21780835 DOI: 10.1021/la202359c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have examined the nanoscale adsorption of molecular water under ambient conditions onto a series of well-characterized functionalized surfaces produced by Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC or "click") reactions on alkyne-terminated self-assembled monolayers on silicon. Water contact angle (CA) measurements reveal a range of macroscopic hydrophilicity that does not correlate with the tendency of these surfaces to adsorb water at the molecular level. X-ray reflectometry has been used to follow the kinetics of water adsorption on these "click"-functionalized surfaces, and also shows that dense continuous molecular water layers are formed over 30 h. For example, a highly hydrophilic surface, functionalized by an oligo(ethylene glycol) moiety (with a CA = 34°) showed 2.9 Å of adsorbed water after 30 h, while the almost hydrophobic underlying alkyne-terminated monolayer (CA = 84°) showed 5.6 Å of adsorbed water over the same period. While this study highlights the capacity of X-ray reflectometry to study the structure of adsorbed water on these surfaces, it should also serve as a warning for those intending to characterize self-assembled monolayers and functionalized surfaces to avoid contamination by even trace amounts of water vapor. Moreover, contact angle measurements alone cannot be relied upon to predict the likely degree of moisture uptake on such surfaces.
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Affiliation(s)
- Michael James
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC NSW 2232, Australia.
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40
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Li Y, Cai C. Click chemistry-based functionalization on non-oxidized silicon substrates. Chem Asian J 2011; 6:2592-605. [PMID: 21751406 DOI: 10.1002/asia.201100294] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Indexed: 11/07/2022]
Abstract
Copper-catalyzed azide-alkyne cycloaddition (CuAAC), combined with the chemical stability of the Si-C-bound organic layer, serves as an efficient tool for the modification of silicon substrates, particularly for the immobilization of complex biomolecules. This review covers recent advances in the preparation of alkynyl- or azido-terminated "clickable" platforms on non-oxidized silicon and their further derivatization by means of the CuAAC reaction. The exploitation of these "click"-functionalized organic thin films as model surfaces to study many biological events was also addressed, as they are directly relevant to the on-going effort of creating silicon-based molecular electronics and chemical/biomolecular sensors.
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Affiliation(s)
- Yan Li
- Department of Chemistry & Center for Materials Chemistry, University of Houston, Houston, Texas 77204, USA
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41
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Ciampi S, James M, Michaels P, Gooding JJ. Tandem "click" reactions at acetylene-terminated Si(100) monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6940-6949. [PMID: 21557551 DOI: 10.1021/la2013733] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We demonstrate a simple method for coupling alkynes to alkynes. The method involves tandem azide-alkyne cycloaddition reactions ("click" chemistry) for the immobilization of 1-alkyne species onto an alkyne modified surface in a one-pot procedure. In the case presented, these reactions take place on a nonoxidized Si(100) surface although the approach is general for linking alkynes to alkynes. The applicability of the method in the preparation of electrically well-behaved functionalized surfaces is demonstrated by coupling an alkyne-tagged ferrocene species onto alkyne-terminated Si(100) surfaces. The utility of the approach in biotechnology is shown by constructing a DNA sensing interface by derivatization of the acetylenyl surface with commercially available alkyne-tagged oligonucleotides. Cyclic voltametry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and X-ray reflectometry are used to characterize the coupling reactions and performance of the final modified surfaces. These data show that this synthetic protocol gives chemically well-defined, electronically well-behaved, and robust (bio)functionalized monolayers on silicon semiconducting surfaces.
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Affiliation(s)
- Simone Ciampi
- School of Chemistry, The University of New South Wales, Sydney NSW 2052, Australia
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42
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Shestopalov AA, Morris CJ, Vogen BN, Hoertz A, Clark RL, Toone EJ. Soft-lithographic approach to functionalization and nanopatterning oxide-free silicon. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6478-6485. [PMID: 21520913 DOI: 10.1021/la200373g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a simple, reliable high-throughput method for patterning passivated silicon with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The approach completely protects silicon from chemical oxidation, provides precise control over the shape and size of the patterned features in the 100 nm domain, and gives rapid, ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules.
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43
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Zhong YL, Bernasek SL. Mild and Efficient Functionalization of Hydrogen-Terminated Si(111) via Sonochemical Activated Hydrosilylation. J Am Chem Soc 2011; 133:8118-21. [DOI: 10.1021/ja2020839] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yu Lin Zhong
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Steven L. Bernasek
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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44
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Puniredd SR, Assad O, Stelzner T, Christiansen S, Haick H. Catalyst-free functionalization for versatile modification of nonoxidized silicon structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:4764-4771. [PMID: 21425837 DOI: 10.1021/la2002546] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Here, we report on a simple, catalyst-free route for obtaining highly versatile subsequent functionalization on Si nanowires and Si(111) substrates. The versatility of this approach allows subsequent functionalization not only for organic species but also for inorganic (nanomaterial) species. The method has the advantage of controlling the density of reactive cross-linkers without affecting the stability of the Si samples and without having metallic (or catalyst) residues on the surface. This method also allows formation of monolayers with a variety of termination groups and is expected to open up a wide range of opportunities for producing stable molecule-based (opto)electronic and (bio)sensing devices. Immobilization of inorganic nanomaterial on the Si samples offers advanced opportunities in molecular switches, (bio)sensors, molecular scale memory, and Si-based nanoelectronic devices.
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Affiliation(s)
- Sreenivasa Reddy Puniredd
- The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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45
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Popoff RTW, Kavanagh KL, Yu HZ. Preparation of ideal molecular junctions: depositing non-invasive gold contacts on molecularly modified silicon. NANOSCALE 2011; 3:1434-1445. [PMID: 21290075 DOI: 10.1039/c0nr00677g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Recent advances in creating rectifying gold|monolayer|silicon (Au-M-Si) junctions (namely, molecular silicon diodes) are reviewed. It is known that direct deposition of gold contacts onto molecular monolayers covalently bonded to silicon surfaces causes notable disruption to the junction structure, resulting in deteriorated performance and poor reproducibility that are unsuitable for practical applications. In the past few years, several new experimental approaches have been explored to minimize or eliminate such damage, including the "indirect" evaporation method and the pre-deposition of a protective "non-penetrating" metal. To enhance the interactions at the gold-monolayer interface, head-groups that allow bonding to gold are used to maintain the monolayer integrity. Construction of the device via flip-chip lamination and the modified polymer-assisted lift-off techniques also prohibits monolayer damage. Refining the fabrication and design techniques towards reliable molecular junctions is crucial if they are to be used in nanoelectronics for the purpose of miniaturization.
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Affiliation(s)
- Richard T W Popoff
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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46
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Scheres L, Rijksen B, Giesbers M, Zuilhof H. Molecular modeling of alkyl and alkenyl monolayers on hydrogen-terminated Si(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:972-980. [PMID: 21207955 DOI: 10.1021/la104705b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
On H-Si(111) surfaces monolayer formation with 1-alkenes results in alkyl monolayers with a Si-C-C linkage, while 1-alkynes yield alkenyl monolayers with a Si-C═C linkage. Recently, considerable structural differences between both types of monolayers were observed, including an increased thickness, improved packing, and higher surface coverage for the alkenyl monolayers. The precise origin thereof could experimentally not be clarified yet. Therefore, octadecyl and octadecenyl monolayers on Si(111) were studied in detail by molecular modeling via PCFF molecular mechanics calculations on periodically repeated slabs of modified surfaces. After energy minimization the packing energies, structural properties, close contacts, and deformations of the Si surfaces of monolayers structures with various substitution percentages and substitution patterns were analyzed. For the octadecyl monolayers all data pointed to a substitution percentage close to 50-55%, which is due the size of the CH(2) groups near the Si surface. This agrees with literature and the experimentally determined coverage of octadecyl monolayers. For the octadecenyl monolayers the minimum in packing energy per chain is calculated around 60% coverage, i.e., close to the experimentally observed value of 65% [Scheres et al. Langmuir 2010, 26, 4790], and this packing energy is less dependent on the substitution percentage than calculated for alkyl layers. Analysis of the chain conformations, close contacts, and Si surface deformation clarifies this, since even at coverages above 60% a relatively low number of close contacts and a negligible deformation of the Si was observed. In order to evaluate the thermodynamic feasibility of the monolayer structures, we estimated the binding energies of 1-alkenes and 1-alkynes to the hydrogen-terminated Si surface at a range of surface coverages by composite high-quality G3 calculations and determined the total energy of monolayer formation by adding the packing energies and the binding energies. It was shown that due to the significantly larger reaction exothermicity of the 1-alkynes, thermodynamically even a substitution percentage as high as 75% is possible for octadecenyl chains. However, because sterically (based on the van der Waals footprint) a coverage of 69% is the maximum for alkyl and alkenyl monolayers, the optimal substitution percentage of octadecenyl monolayers will be presumably close to this latter value, and the experimentally observed 65% is likely close to what is experimentally maximally obtainable with alkenyl monolayers.
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Affiliation(s)
- Luc Scheres
- Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands
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47
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Ciampi S, James M, Darwish N, Luais E, Guan B, Harper JB, Gooding JJ. Oxidative acetylenic coupling reactions as a surface chemistry tool. Phys Chem Chem Phys 2011; 13:15624-32. [DOI: 10.1039/c1cp21450k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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48
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Lavi A, Cohen H, Bendikov T, Vilan A, Cahen D. Si–C-bound alkyl chains on oxide-free Si: towards versatile solution preparation of electronic transport quality monolayers. Phys Chem Chem Phys 2011; 13:1293-6. [PMID: 21132168 DOI: 10.1039/c0cp01445a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Avi Lavi
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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49
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Masood MN, Chen S, Carlen ET, van den Berg A. All-(111) surface silicon nanowires: selective functionalization for biosensing applications. ACS APPLIED MATERIALS & INTERFACES 2010; 2:3422-3428. [PMID: 21090766 DOI: 10.1021/am100922e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We demonstrate the utilization of selective functionalization of carbon-silicon (C-Si) alkyl and alkenyl monolayers covalently linked to all-(111) surface silicon nanowire (Si-NW) biosensors. Terminal amine groups on the functional monolayer surfaces were used for conjugation of biotin n-hydroxysuccinimide ester. The selective functionalization is demonstrated by contact angle, X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HRSEM) of 5 nm diameter thiolated Au nanoparticles linked with streptavidin and conjugated to the biotinylated all-(111) surface Si-NWs. Electrical measurements of monolayer passivated Si-NWs show improved device behavior and performance. Furthermore, an analytical model is presented to demonstrate the improvement in detection sensitivity of the alkyl and alkenyl passivated all-(111) Si-NW biosensors compared to conventional nanowire biosensor geometries and silicon dioxide passivation layers as well as interface design and electrical biasing guidelines for depletion-mode sensors.
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50
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Scheres L, Klingebiel B, ter Maat J, Giesbers M, de Jong H, Hartmann N, Zuilhof H. Micro- and nanopatterning of functional organic monolayers on oxide-free silicon by laser-induced photothermal desorption. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:1918-1926. [PMID: 20677184 DOI: 10.1002/smll.201000189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The photothermal laser patterning of functional organic monolayers, prepared on oxide-free hydrogen-terminated silicon, and subsequent backfilling of the laser-written lines with a second organic monolayer that differs in its terminal functionality, is described. Since the thermal monolayer decomposition process is highly nonlinear in the applied laser power density, subwavelength patterning of the organic monolayers is feasible. After photothermal laser patterning of hexadecenyl monolayers, the lines freed up by the laser are backfilled with functional acid fluoride monolayers. Coupling of cysteamine to the acid fluoride groups and subsequent attachment of Au nanoparticles allows easy characterization of the functional lines by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Depending on the laser power and writing speed, functional lines with widths between 1.1 μm and 250 nm can be created. In addition, trifluoroethyl-terminated (TFE) monolayers are also patterned. Subsequently, the decomposed lines are backfilled with a nonfunctional hexadecenyl monolayer, the TFE stripes are converted into thiol stripes, and then finally covered with Au nanoparticles. By reducing the lateral distance between the laser lines, Au-nanoparticle stripes with widths close to 100 nm are obtained. Finally, in view of the great potential of this type of monolayer in the field of biosensing, the ease of fabricating biofunctional patterns is demonstrated by covalent binding of fluorescently labeled oligo-DNA to acid-fluoride-backfilled laser lines, which--as shown by fluorescence microscopy--is accessible for hybridization.
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Affiliation(s)
- Luc Scheres
- Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, Wageningen 6703 HB, The Netherlands
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