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Garvey S, Holmes JD, Kim YS, Long B. Vapor-Phase Passivation of Chlorine-Terminated Ge(100) Using Self-Assembled Monolayers of Hexanethiol. ACS APPLIED MATERIALS & INTERFACES 2020; 12:29899-29907. [PMID: 32501666 DOI: 10.1021/acsami.0c02548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Continued scaling of electronic devices shows the need to incorporate high mobility alternatives to silicon, the cornerstone of the semiconductor industry, into modern field effect transistor (FET) devices. Germanium is well-poised to serve as the channel material in FET devices as it boasts an electron and hole mobility more than twice and four times that of Si, respectively. However, its unstable native oxide makes its passivation a crucial step toward its potential integration into future FETs. The International Roadmap for Devices and Systems (IRDS) predicts continued aggressive scaling not only of the device size but also of the pitch in nanowire arrays. The development of a vapor-phase chemical passivation technique will be required to prevent the collapse of these structures that can occur because of the surface tension and capillary forces that are experienced when tight-pitched nanowire arrays are processed via liquid-phase chemistry. Reported here is a vapor-phase process using hexanethiol for the passivation of planar Ge(100) substrates. Results benchmarking it against its well-established liquid-phase equivalent are also presented. X-ray photoelectron spectroscopy was used to monitor the effectiveness of the developed vapor-phase protocol, where the presence of oxide was monitored at 0, 24, and 168 h. Water contact angle measurements compliment these results by demonstrating an increase in hydrophobicity of the passivated substrates. Atomic force microscopy monitored the surface topology before and after processing to ensure the process does not cause roughening of the surface, which is critical to demonstrate suitability for nanostructures. It is shown that the 200 min vapor-phase passivation procedure generates stable, passivated surfaces with less roughness than the liquid-phase counterpart.
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Affiliation(s)
- Shane Garvey
- School of Chemistry & AMBER Centre, University College Cork, Cork T12 YN60, Ireland
- Tyndall National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Justin D Holmes
- School of Chemistry & AMBER Centre, University College Cork, Cork T12 YN60, Ireland
| | - Y S Kim
- Lam Research Corp., Fremont, California 94538, United States
| | - Brenda Long
- School of Chemistry & AMBER Centre, University College Cork, Cork T12 YN60, Ireland
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On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols. SURFACES 2018. [DOI: 10.3390/surfaces1010004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The passivation of metal electrodes covered by self-assembled monolayers of long-chain thiols is well known. The disappearance of the voltammetric peak of redox species in solution is a classical test for the formation of full layers of thiols. Similar studies on semiconductors are still very limited. We used silver surfaces covered by an ultrathin layer of CdS as substrate for self-assembling of n-hexadecanethiol (C16SH), and we compared the experimental results with those obtained by using the bare silver surface as substrate. The strong insulating effect of C16SH deposited on Ag(III) is shown by the inhibition of the voltammetric peak of Ru(NH3)63+/2+. On the contrary, the voltammogram obtained on CdS-covered Ag(III) is very similar to that obtained on the bare Ag(III) electrode, thus suggesting that the presence of CdS exerts a contrasting effect on the passivation of the silver electrode. A crucial point of our work is to demonstrate the effective formation of C16SH monolayers on Ag(III) covered by CdS. The formation of full layers of C16SH was strongly suggested by the inhibition of the stripping peak of Cd from the CdS deposit covered by C16SH. The presence of C16SH was confirmed by electrochemical quartz crystal microbalance (EQCM) measurements as well as by Auger electron spectroscopy (AES) analysis.
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Rojas Delgado R, Jacobberger RM, Roy SS, Mangu VS, Arnold MS, Cavallo F, Lagally MG. Passivation of Germanium by Graphene. ACS APPLIED MATERIALS & INTERFACES 2017; 9:17629-17636. [PMID: 28474879 DOI: 10.1021/acsami.7b03889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The oxidation of Ge covered with graphene that is either grown on or transferred to the surface is investigated by X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy. Graphene properly grown by chemical vapor deposition on Ge(100), (111), or (110) effectively inhibits room-temperature oxidation of the surface. When graphene is transferred to the Ge surface, oxidation is reduced relative to that on uncovered Ge but has the same power law dependence. We conclude that access to the graphene/Ge interface must occur via defects in the graphene. The excellent passivation provided by graphene grown on Ge should enhance applications of Ge in the electronic-device industry.
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Affiliation(s)
- Richard Rojas Delgado
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Robert M Jacobberger
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Susmit Singha Roy
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Vijay Saradhi Mangu
- Department of Electrical Engineering and Center for High-Technology Materials, University of New Mexico , Albuquerque, New Mexico 87132, United States
| | - Michael S Arnold
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Francesca Cavallo
- Department of Electrical Engineering and Center for High-Technology Materials, University of New Mexico , Albuquerque, New Mexico 87132, United States
| | - Max G Lagally
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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Schartner J, Gavriljuk K, Nabers A, Weide P, Muhler M, Gerwert K, Kötting C. Immobilization of Proteins in their Physiological Active State at Functionalized Thiol Monolayers on ATR-Germanium Crystals. Chembiochem 2014; 15:2529-34. [DOI: 10.1002/cbic.201402478] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 11/09/2022]
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Hohman JN, Kim M, Lawrence JA, McClanahan PD, Weiss PS. High-fidelity chemical patterning on oxide-free germanium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:164214. [PMID: 22466616 DOI: 10.1088/0953-8984/24/16/164214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Oxide-free germanium can be chemically patterned directly with self-assembled monolayers of n-alkanethiols via submerged microcontact printing. Native germanium dioxide is water soluble; immersion activates the germanium surface for self-assembly by stripping the oxide. Water additionally provides an effective diffusion barrier that prevents undesired ink transport. Patterns are stable with respect to molecular exchange by carboxyl-functionalized thiols.
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Affiliation(s)
- J Nathan Hohman
- California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Alévêque O, Blanchard PY, Breton T, Dias M, Gautier C, Levillain E. Revisiting the determination of full steady-state coverage of redox centers on self-assembled monolayers. Electrochem commun 2012. [DOI: 10.1016/j.elecom.2011.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Kachian JS, Tannaci J, Wright RJ, Tilley TD, Bent SF. Disulfide passivation of the Ge(100)-2 × 1 surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:179-186. [PMID: 21141841 DOI: 10.1021/la103614f] [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
Understanding the bonding of sulfur at the germanium surface is important to developing good passivation routes for germanium-based electronic devices. The adsorption behavior of ethyl disulfide (EDS) and 1,8-naphthalene disulfide (NDS) at the Ge(100)-2 × 1 surface has been studied under ultrahigh vacuum conditions to investigate both their fundamental reactivity and their effectiveness as passivants of this surface. X-ray photoelectron spectroscopy, multiple internal reflection-infrared spectroscopy, and density functional theory results indicate that both molecules adsorb via S-S dissociation at room temperature. Upon exposure to ambient air, the thiolate adlayer remains intact for both EDS- and NDS-functionalized surfaces, indicating the stability of this surface attachment. Although both systems resist oxidation compared to the bare Ge(100)-2 × 1 surface, the Ge substrate is significantly oxidized in all cases (17-57% relative to the control), with the NDS-passivated surface undergoing up to two times more oxidation than the EDS-passivated surface at the longest air exposure times studied. The difference in passivation capability is attributed to the difference in surface coverage on Ge(100)-2 × 1, where EDS adsorption leads to a saturation coverage 17% higher than that for NDS/Ge(100)-2 × 1.
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Affiliation(s)
- Jessica S Kachian
- Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, United States
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Hohman JN, Kim M, Bednar HR, Lawrence JA, McClanahan PD, Weiss PS. Simple, robust molecular self-assembly on germanium. Chem Sci 2011. [DOI: 10.1039/c1sc00115a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Ardalan P, Sun Y, Pianetta P, Musgrave CB, Bent SF. Reaction mechanism, bonding, and thermal stability of 1-alkanethiols self-assembled on halogenated Ge surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8419-8429. [PMID: 20433151 DOI: 10.1021/la904864c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have employed synchrotron radiation photoemission spectroscopy to study the reaction mechanism, surface bonding, and thermal stability of 1-octadecanethiolate (ODT) self-assembled monolayers (SAMs) at Cl- and Br-terminated Ge(100) surfaces. Density functional theory (DFT) calculations were also carried out for the same reactions. From DFT calculations, we have found that adsorption of 1-octadecanethiol on the halide-terminated surface via hydrohalogenic acid elimination is kinetically favorable on both Cl- and Br-terminated Ge surfaces at room temperature, but the reactions are more thermodynamically favorable at Cl-terminated Ge surfaces. After ODT SAM formation at room temperature, photoemission spectroscopy experiments show that Ge(100) and (111) surfaces contain monothiolates and possibly dithiolates together with unbound thiol and atomic sulfur. Small coverages of residual halide are also observed, consistent with predictions by DFT. Annealing studies in ultrahigh vacuum show that the Ge thiolates are thermally stable up to 150 degrees C. The majority of the surface thiolates are converted to sulfide and carbide upon annealing to 350 degrees C. By 430 degrees C, no sulfur remains on the surface, whereas Ge carbide is stable to above 470 degrees C.
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Affiliation(s)
- Pendar Ardalan
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
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Kachian JS, Bent SF. Sulfur versus Oxygen Reactivity of Organic Molecules at the Ge(100)-2×1 Surface. J Am Chem Soc 2009; 131:7005-15. [DOI: 10.1021/ja808066t] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jessica S. Kachian
- Department of Chemical Engineering, Stanford University, Stanford, California 94305
| | - Stacey F. Bent
- Department of Chemical Engineering, Stanford University, Stanford, California 94305
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Ardalan P, Musgrave CB, Bent SF. Formation of alkanethiolate self-assembled monolayers at halide-terminated Ge surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:2013-2025. [PMID: 19152272 DOI: 10.1021/la803468e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have studied Ge halide passivation and formation of 1-octadecanethiolate self-assembled monolayers (SAMs) at Cl- and Br-terminated Ge(100) and Ge(111) surfaces. The results of water contact angle measurements, ellipsometry, transmission infrared spectroscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy show that good quality 1-alkanethiolate SAMs can be achieved at both Cl- and Br-terminated surfaces via direct Ge-S bonds. The quality of the SAMs depends on the concentration and the solvent of the 1-alkanethiol solution. Moreover, SAMs formed at Ge(100) surfaces have higher water contact angles, thicknesses, and ambient stability than those formed at Ge(111) surfaces. Surface passivation and light are found to play an important role in the packing and stability of the SAMs. Furthermore, well-packed SAMs can be retrieved by repassivation after degradation due to ambient exposure. This work presents novel routes for Ge surface passivation.
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Affiliation(s)
- Pendar Ardalan
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
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Gerung H, Boyle TJ, Tribby LJ, Bunge SD, Brinker CJ, Han SM. Solution synthesis of germanium nanowires using a Ge2+ alkoxide precursor. J Am Chem Soc 2007; 128:5244-50. [PMID: 16608360 PMCID: PMC2538547 DOI: 10.1021/ja058524s] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A simple solution synthesis of germanium (Ge0) nanowires under mild conditions (<400 degrees C and 1 atm) was demonstrated using germanium 2,6-dibutylphenoxide, Ge(DBP)2 (1), as the precursor where DBP = 2,6-OC6H3(C(CH3)3)2. Compound 1, synthesized from Ge(NR2)2 where R = SiMe3 and 2 equiv of DBP-H, was characterized as a mononuclear species by single-crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 degrees C under an atmosphere of Ar, led to the formation of Ge0 nanowires. The Ge0 nanowires were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1-10 microm) increases with increasing temperature (285-315 degrees C) and time (5-60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire; and (2) self-assembly mechanism where an aggregate of small rods (<50 nm in diameter) recrystallizes on the tip of a longer wire, extending its length.
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Affiliation(s)
- Henry Gerung
- Department of Chemical and Nuclear Engineering, University of New Mexico, 209 Farris Engineering Center, Albuquerque, NM 87131
| | - Timothy J. Boyle
- Advanced Materials Laboratory, Sandia National Laboratories, 1001 University Blvd SE, Albuquerque, NM 87106
- Author to whom correspondences should be sent: Timothy J. Boyle [Ph: (505) 272-7625, Fax: (505-272-7663, E-mail: ] and Sang M. Han [Ph: (505)277-3118; Fax: (505)277-5431; ]
| | - Louis J. Tribby
- Advanced Materials Laboratory, Sandia National Laboratories, 1001 University Blvd SE, Albuquerque, NM 87106
| | - Scott D. Bunge
- Advanced Materials Laboratory, Sandia National Laboratories, 1001 University Blvd SE, Albuquerque, NM 87106
| | - C. Jeffrey Brinker
- Department of Chemical and Nuclear Engineering, University of New Mexico, 209 Farris Engineering Center, Albuquerque, NM 87131
- Advanced Materials Laboratory, Sandia National Laboratories, 1001 University Blvd SE, Albuquerque, NM 87106
| | - Sang M. Han
- Department of Chemical and Nuclear Engineering, University of New Mexico, 209 Farris Engineering Center, Albuquerque, NM 87131
- Author to whom correspondences should be sent: Timothy J. Boyle [Ph: (505) 272-7625, Fax: (505-272-7663, E-mail: ] and Sang M. Han [Ph: (505)277-3118; Fax: (505)277-5431; ]
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13
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Lee KH, Chen SJ, Jeng JY, Cheng YC, Shiea JT, Chang HT. Fluorescence and interactions with thiol compounds of Nile Red-adsorbed gold nanoparticles. J Colloid Interface Sci 2007; 307:340-8. [PMID: 17207807 DOI: 10.1016/j.jcis.2006.12.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/23/2006] [Accepted: 12/03/2006] [Indexed: 10/23/2022]
Abstract
We have investigated the interactions between a variety of thiols and Nile Red-adsorbed gold nanoparticles (NRAuNPs). After adding thiols to solutions of NRAuNPs, the solutions fluoresce strongly as a result of the displacement of a Nile Red-derived product from the surface of the AuNPs. We propose a mechanism for the formation of this NR product on the surface of AuNPs by conducting mass spectrometry, fluorescence, and capillary electrophoresis measurements. By recording the fluorescence changes of the NRAuNP solutions after addition of the thiols, we investigated the interactions between the thiols and NRAuNPs. Using the Langmuir isotherm model, we found that the displacement rate constants for thiols having one carboxyl residue, such as 3-mercaptopropionic acid, fall within the range 0.55-1.19 x 10(-2) s(-1). Thiols containing hydroxyl groups [e.g., 2-mercaptoethanol (2-ME)] or amino groups [e.g., N-(2-mercaptopropionyl)glycine (MPG)], or that have flat structures on the AuNP surface, such as mercaptosuccinic acid, exhibit double-exponential kinetics with first rate constants of 0.51-2.83 x 10(-2) s(-1) and second rate constants of 6.0-23.4 x 10(-4) s(-1). Our results reveal that steric effects and the charge density of the thiols both play important roles in determining the interactions with NRAuNPs. The interactions (displacement and/or induced aggregation) are also dependent on the size of NRAuNPs.
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Affiliation(s)
- Kun-Hong Lee
- Department of Chemistry, National Taiwan University, Roosevelt Road, Sec. 4, Taipei 106, Taiwan
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Loscutoff PW, Bent SF. REACTIVITY OF THE GERMANIUM SURFACE: Chemical Passivation and Functionalization. Annu Rev Phys Chem 2006; 57:467-95. [PMID: 16599818 DOI: 10.1146/annurev.physchem.56.092503.141307] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
With the rapidly changing materials needs of modern microelectronics, germanium provides an opportunity for future-generation devices. Controlling germanium interfaces will be essential for this purpose. We review germanium surface reactivity, beginning with a description of the most commonly used surfaces, Ge(100) and Ge(111). An analysis of oxide formation shows why the poor oxide properties have hindered practical use of germanium to date. This is followed by an examination of alternate means of surface passivation, with particular attention given to sulfide, chloride, and hydride termination. Specific tailoring of the interface properties is possible through organic functionalization. The few solution functionalization methods that have been studied are reviewed. Vacuum functionalization has been studied to a much greater extent, with dative bonding and cycloaddition reactions emerging as principle reaction mechanisms. These are reviewed through molecular reaction studies that demonstrate the versatility of the germanium surface.
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Affiliation(s)
- Paul W Loscutoff
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
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McGuiness CL, Shaporenko A, Mars CK, Uppili S, Zharnikov M, Allara DL. Molecular Self-Assembly at Bare Semiconductor Surfaces: Preparation and Characterization of Highly Organized Octadecanethiolate Monolayers on GaAs(001). J Am Chem Soc 2006; 128:5231-43. [PMID: 16608359 DOI: 10.1021/ja058657d] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Through rigorous control of preparation conditions, organized monolayers with a highly reproducible structure can be formed by solution self-assembly of octadecanethiol on GaAs (001) at ambient temperature. A combination of characterization probes reveal a structure with conformationally ordered alkyl chains tilted on average at 14 +/- 1 degrees from the surface normal with a 43 +/- 5 degrees twist, a highly oleophobic and hydrophobic ambient surface, and direct S-GaAs attachment. Analysis of the tilt angle and film thickness data shows a significant mismatch of the average adsorbate molecule spacings with the spacings of an intrinsic GaAs(001) surface lattice. The monolayers are stable up to approximately 100 degrees C and exhibit an overall thermal stability which is lower than that of the same monolayers on Au[111] surfaces. A two-step solution assembly process is observed: rapid adsorption of molecules over the first several hours to form disordered structures with molecules lying close to the substrate surface, followed by a slow densification and asymptotic approach to final ordering. This process, while similar to the assembly of alkanethiols on Au[111], is nearly 2 orders of magnitude slower. Finally, despite differences in assembly rates and the thermal stability, exchange experiments with isotopically tagged molecules show that the octadecanethiol on GaAs(001) monolayers undergo exchange with solute thiol molecules at roughly the same rate as the corresponding exchanges of the same monolayers on Au[111].
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Affiliation(s)
- Christine L McGuiness
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16801-6300, USA
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Mirji SA. Octadecyltrichlorosilane adsorption kinetics on Si(100)/SiO2 surface: contact angle, AFM, FTIR and XPS analysis. SURF INTERFACE ANAL 2006. [DOI: 10.1002/sia.2309] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wang D, Chang YL, Liu Z, Dai H. Oxidation Resistant Germanium Nanowires: Bulk Synthesis, Long Chain Alkanethiol Functionalization, and Langmuir−Blodgett Assembly. J Am Chem Soc 2005; 127:11871-5. [PMID: 16104766 DOI: 10.1021/ja053836g] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A simple method is developed to synthesize gram quantities of uniform Ge nanowires (GeNWs) by chemical vapor deposition on preformed, monodispersed seed particles loaded onto a high surface area silica support. Various chemical functionalization schemes are investigated to passivate the GeNW surfaces using alkanethiols and alkyl Grignard reactions. The stability of functionalization against oxidation of germanium for various alkyl chain lengths is elucidated by X-ray photoelectron spectroscopy. Among all schemes tested, long chain alkanethiols (> or = C12) are found to impart the most stable GeNW passivation against oxidation upon extended exposure to ambient air. Further, the chemically functionalized oxidation-resistant nanowires are soluble in organic solvents and can be readily assembled into close-packed Langmuir-Blodgett films potentially useful for future high performance electronic devices.
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Affiliation(s)
- Dunwei Wang
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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