Faculty Profiles - SAITO, Nagahiro

Papers - SAITO, Nagahiro

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Electrodeposition of CuInTe<inf>2</inf> film from an acidic solution

Ishizaki T., Saito N., Fuwa A.

Surface and Coatings Technology Vol. 182 ( 2-3 ) page： 156 - 160 2004.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface and Coatings Technology

Copper-indium-telluride films were electrochemically deposited from solutions containing CuCl2, InCl3, TeO2 and HCl. Although a flat and smooth film with closely stoichiometric composition was deposited at -660 mV vs. Ag/AgCl at 303 K from a solution of 2.5×10-4 mol dm-3 CuCl2, 1.0×10-2 mol dm-3 InCl3, 5.0×10-4 mol dm-3 TeO2 and 0.1 mol dm-3 HCl, a polycrystalline CuInTe2 film was not obtained. Increasing the temperature from 303 to 363 K allowed the deposition at lower overpotential of a polycrystalline CuInTe2 film with closely stoichiometric composition and increased indium content. The band gap of the polycrystalline CuInTe2 film electrodeposited at 363 K at -660 mV was 0.98 eV. © 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.surfcoat.2003.07.004

Surface potential microscopy for chemistry of organic self-assembled monolayers in small domains

Sugimura H., Saito N., Maeda N., Ikeda I., Ishida Y., Hayashi K., Hong L., Takai O.

Nanotechnology Vol. 15 ( 2 ) 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Nanotechnology

Micropatterning techniques using vacuum ultra-violet light at 172 nm in wavelength and an ultra-violet laser at 244 nm were applied to organosilane self-assembled monolayers (SAMs) formed on Si substrates covered with a 2 nm thick oxide layer. These SAMs were prepared from precursors, that is, octadecyltrimethoxysilane (ODS) or p-chloromethylphenyltrimethoxysilane (CMPhS). Polar functional groups such as COOH were generated through photochemical oxidation of the SAMs. Furthermore, the SAMs were Simultaneously etched and finally removed from the photoirradiated area. Surface potentials of the photoirradiated areas at various irradiation dose rates were measured by Kelvin-probe force microscopy (KFM) using the unirradiated area on each of the photopatterned samples as a reference. Changes in the surface chemical composition of the SAMs could be clearly and sensitively measured by KFM through the difference in surface potential between the irradiated and unirradiated SAMs.

DOI： 10.1088/0957-4484/15/2/015

Oxygen gas assisted electron beam lithography in organosilane self-assembled monolayers

Yamaguchi M., Saito N., Takai O.

Digest of Papers - Microprocesses and Nanotechnology 2004 page： 198 - 199 2004

Microstructured π-conjugated organic monolayer covalently attached to silicon

Saito N., Hayashi K., Sugimura H., Takai O.

Langmuir Vol. 19 ( 26 ) page： 10632 - 10634 2003.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Langmuir

A phenylacetylene (PA) monolayer was prepared on hydrogen-terminated silicon. Through vacuum ultraviolet (VUV) lithography, micropatterned PA-monolayer/SiO2 samples were subsequently fabricated. The surface potential and electrical conductivity of the microstructured PA monolayers were examined by Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (C-AFM), respectively. KPFM measurements showed that the PA-monolayer surface regions were negatively charged. C-AFM measurements demonstrated that, in the microdomains, the PA-monolayer regions had a higher conductivity than the SiO2 regions fabricated by VUV lithography. This is the first report of electronic property images of a monolayer directly attached to silicon being demonstrated in microregions.

DOI： 10.1021/la034187u

Origin of N 1s spectrum in amorphous carbon nitride obtained by X-ray photoelectron spectroscopy

Ohta R., Lee K.H., Saito N., Inoue Y., Sugimura H., Takai O.

Thin Solid Films Vol. 434 ( 1-2 ) page： 296 - 302 2003.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Thin Solid Films

This paper focuses on determining a reasonable peak assignment for the N 1s spectrum of amorphous carbon nitride (a-CN) measured by X-ray photoelectron spectroscopy (XPS). Unfortunately, several peaks of a-CN have not been identified, that is, there has yet to be any shared understanding of their chemical bonding states. We investigated this by monitoring changes in spectra before and after vacuum ultraviolet (VUV) irradiation, thus obtaining information about the changes of chemical bonds. The observed changes were discussed based on the chemical shifts of components of a-CN determined from ab-initio molecular orbital (MO) calculations. We have proposed the following peak assignment for N 1s. The peaks located at approximately (1) 397.6, (2) 398.2, (3) 399.0, (4) 400.0, (5) 400.9 and (6) 401.9 eV were assigned to the chemical bonding states of (1) β-C 3 N 4 , (2) pyridine, (3) formonitril, (4) methylmethyleneamine, (5) pyrido[2,1,6-de]quinolizine, and (6) a nitroso group. This assignment did not agree with oft-quoted ones. However, only this peak assignment provides a reasonable interpretation for the changes we observed in a-CN introduced by VUV irradiation, and allows us to understand the chemical bonding states of a-CN film. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00457-7

Selective immobilization of functional organic molecules onto a microtemplate fabricated using an amino-terminated self-assembled monolayer

Hayashi K., Hozumi A., Saito N., Sugimura H., Takai O.

Surface Science Vol. 532-535 page： 1072 - 1078 2003.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface Science

Micropatterned amino-terminated self-assembled monolayers (SAMs) were applied as templates to promote selective chemical reactions in minute spatial scale. The surface charge properties of the SAMs were investigated through zeta-potential measurements conducted in solutions of various pH values. These SAMs were then utilized in order to selectively immobilize carboxylate-modified fluorescence spheres (CM-FluoSpheres) on the sample surface. Each SAM was uniformly formed onto a clean Si(1 0 0) substrate covered with a thin oxide layer (SiO2) by chemical vapor deposition using n-(6-aminohexyl)aminopropyltrimethoxysilane [AHAPS:H2N(CH2)6NH(CH2)3S i(OCH3)3] as a precursor. Through a photolithographic technique employing vacuum ultraviolet light at 172 nm, microstructures consisting of AHAPS-SAM and SiO2 were fabricated. The micropatterned AHAPS-SAM/SiO2 samples were then immersed in a solution dispersed with CM-FluoSpheres. The solution was adjusted to pH = 2, 6 or 8. At pH = 8, the CM-FluoSpheres did not adsorb on the micropatterned AHAPS-SAM/SiO2. At pH = 2 and 6, the CM-FluoSpheres adsorbed specifically on the regions covered with AHAPS-SAM. In particular, the adsorption behavior at pH = 6 was highly selective. These results were predictable considering the isoelectric points of AHAPS-SAM and SiO2, that is, pH = 7.5 and 2.0, respectively. At pH = 6, the SiO2 surface was negatively charged while the AHAPS-SAM surface was positive. Since the CM-FluoSpheres, which are terminated with carboxyl groups, were negatively charged at this pH value, the SiO2 and AHAPS-SAM surfaces had repulsive and attractive interactions, respectively, with the CM-FluoSpheres. These opposite electrostatic interactions were the origin of the complete selectivity achieved in the adsorption. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0039-6028(03)00211-5

Chemical resistivity of self-assembled monolayer covalently attached to silicon substrate to hydrofluoric acid and ammonium fluoride

Saito N., Youda S., Hayashi K., Sugimura H., Takai O.

Surface Science Vol. 532-535 page： 970 - 975 2003.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface Science

Self-assembled monolayers (SAMs) were prepared on hydrogen-terminated silicon substrates through chemical vapor deposition using 1-hexadecene (HD) as a precursor. The HD-SAMs prepared in an atmosphere under a reduced pressure (≈50 Pa) showed better chemical resistivities to hydrofluoric acid and ammonium fluoride (NH4F) solutions than that of an organosilane SAM formed on oxide-covered silicon substrates. The surface covered with the HD-SAM was micro-patterned by vacuum ultraviolet photolithography and consequently divided into two areas terminated with HD-SAM or silicon dioxide. This micro-patterned sample was immersed in a 40 vol.% NH4F aqueous solution. Surface images obtained by an optical microscopy clearly show that the micro-patterns of HD-SAM/silicon dioxide were successfully transferred into the silicon substrate. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0039-6028(03)00158-4

Micropatterned 1-alkene self-assembled monolayer on hydrogen-terminated silicon by vacuum ultraviolet lithography

Saito N., Kadoya Y., Hayashi K., Sugimura H., Takai O.

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers Vol. 42 ( 4 B ) page： 2534 - 2537 2003.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers

We fabricated micropatterned 1-alkene self-assembled monolayers (SAMs) on p-type Si(111). 1-Alkene SAMs were prepared from 1-hexadecene (HD) and 1-octadecene (OD) through reduced pressure chemical vapor deposition. Those SAMs were micropatterned by vacuum ultraviolet (VUV) light lithography. The 1-alkene SAMs irradiated for 30 min were measured by X-ray photoelectron spectroscopy (XPS). The sample surface irradiated for 30 min was covered with shorter alkyl chains with carboxyl end groups on SiOx since the O and OH radicals produced by VUV irradiation react with alkyl chains. We measured surface potential images of those micro-patterned SAMs with Kelvin probe force microscopy (KPFM). The surface potentials of HD- and OD-SAMs were +60 and +90mV against irradiated regions. The regions of 1-alkene SAMs show higher surface potential than those of irradiated regions due to the presence of carboxyl end groups. The regions of HD- and OD-SAMs showed positive surface potentials against those of irradiated regions. This irradiated region was confirmed to be a carboxyl-terminated surface with short alkyl chains based on XPS analysis. The carboxyl groups are negatively charged, so the surface potential of the irradiated regions is negative against the HD- and OD-SAM regions.

DOI： 10.1143/jjap.42.2534

Principle in imaging contrast in scanning electron microscopy for binary microstructures composed of organosilane self-assembled monolayers

Saito N., Wu Y., Hayashi K., Sugimura H., Takai O.

Journal of Physical Chemistry B Vol. 107 ( 3 ) page： 664 - 667 2003.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physical Chemistry B

Field-emission electron microscopy (FE-SEM) was applied to observe coplanar microstructures composed of two different types of organosilane self-assembled monolayers (SAMs). These binary microstructures were prepared on silicon substrates covered with native oxide by a lithographic technique. Four types of organosilane precursors, they are n-octadecyltrimethoxysilane (ODS), heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (a type of fluoroalkylsilane, FAS), n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS), and 4-(chloromethyl)phenyltrimethoxysilane (CMPhS), were used in this study. Micropatterns composed of the SAMs were clearly imaged by FE-SEM at low acceleration voltages, around 0.6 kV. The brightness order of the SAMs in FE-SEM was ODS > AHAPS > CMPhS > FAS. Through ab initio molecular orbital calculations, the origin of this FE-SEM contrast was ascribed to the electron affinity between the SAMs, which governed the FE-SEM image contrast. It has been successfully demonstrated that FE-SEM could provide us chemical information on organic films with a monomolecular thickness on a solid support.

DOI： 10.1021/jp021362r

Imaging micropatterned organosilane self-assembled monolayers on silicon by means of scanning electron microscopy and Kelvin probe force microscopy

Wu Y., Hayashi K., Saito N., Sugimura H., Takai O.

Surface and Interface Analysis Vol. 35 ( 1 ) page： 94 - 98 2003.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface and Interface Analysis

Field-emission scanning electron microscopy (FE-SEM) and surface potentiometry based on scanning probe microscopy, i.e. Kelvin probe force microscopy (KFM), have been applied to study microstructures consisting of organosilane self-assembled monolayers (SAMs) terminated with -CH3 or -CF3 groups. Onto cleaned Si substrates covered with a thin oxide layer of 2 nm thick, SAMs were formed by chemical vapour deposition using n-octadecyltrimethoxysilane (CH3(CH2)17Si(OCH3)3, ODS) or fluoroalkylsilane (CF3(CF2)7(CH2)2Si (OCH3)3, FAS) as a precursor. Through a photolithographic technique employing vacuum ultraviolet light at 172 nm, microstructures composed of ODS, FAS or both were fabricated. Micropatterns of the SAMs on SiO2/Si substrates were clearly imaged by FE-SEM at an acceleration voltage of the electron beam below 1 kV, but image contrasts became faint with an increase in the acceleration voltage. At a voltage of 5 kV there was almost no detectable contrast. An FE-SEM image of the ODS-FAS microstructure acquired at an acceleration voltage of 0.8 kV clearly demonstrated that the region covered with ODS was brighter and thus, emitted secondary electrons more efficiently than the region covered with FAS. Furthermore, as indicated in a KFM image, the region covered with FAS had a surface potential ∼180 mV lower than that of the region covered with ODS. The origin of these image contrasts between ODS- and FAS-SAMs was the large difference in electronic states between ODS and FAS owing to the electron negativity of fluorine atoms.

DOI： 10.1002/sia.1501

Scanning probe surface modification: Chemical conversion of terminal functional groups on organosilane self-assembled monolayers

Sugimura, H; Saito, N; Hayashi, K; Maeda, N; Takai, O

SCANNING TUNNELING MICROSCOPY/SPECTROSCOPY AND RELATED TECHNIQUES Vol. 696 page： 150 - 157 2003

Alkyl self-assembled monolayer prepared on hydrogen-terminated Si(111) through reduced pressure chemical vapor deposition: Chemical resistivities in HF and NH<inf>4</inf>F solutions

Saito N., Youda S., Hayashi K., Sugimura H., Takai O.

Chemistry Letters ( 12 ) page： 1194 - 1195 2002.12

Regulation of the surface potential of silicon substrates in micrometer scale with organosilane self-assembled monolayers

Hayashi K., Saito N., Sugimura H., Takai O., Nakagiri N.

Langmuir Vol. 18 ( 20 ) page： 7469 - 7472 2002.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Langmuir

Microstructures composed of two types of organosilane self-assembled monolayers (SAMs) terminated with different functional groups have been constructed on silicon substrates covered with native oxide. Surface potential images of these microstructures were acquired by Kelvin-probe force microscopy (KFM). By chemical vapor deposition (CVD), the SAMs were fabricated from n-octadecyltrimethoxysilane (ODS) [H3C(CH2)17Si(OCH3)3], fluoroalkylsilane (FAS), that is, heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane [F3C(CF2)7(CH2)2Si(OCH 3)3], and n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS) [H2N(CH2)6NH(CH2)3Si(OCH 3)3]. Through a photolithographic technique, binary microstructures consisting of ODS/FAS and ODS/AHAPS were constructed. A surface potential contrast of the two SAMs in each of the binary microstructures was clearly detected by KFM. The surface potential of the FAS-terminated region was ca. 180 mV lower than that of the ODS-terminated region, while the potential of the AHAPS-terminated region was ca. 50 Mv higher. These results agree with surface potentials of the SAMs predicted from dipole moments of the corresponding precursor organosilane molecules as estimated by ab initio molecular orbital (MO) calculations. Moreover, by applying the surface potential contrasts experimentally acquired by KFM to surface potential contrast occupied area with single molecule curves theoretically derived by MO calculations, packing densities of the SAMs prepared by CVD were confirmed ta be smaller than those of Langmuir-Blodgett monolayers.

DOI： 10.1021/la011707h

The decomposition mechanism of p-chloromethylphenyltrimethoxysiloxane self-assembled monolayers on vacuum ultraviolet irradiation

Saito N., Hayashi K., Sugimura H., Takai O.

Journal of Materials Chemistry Vol. 12 ( 9 ) page： 2684 - 2687 2002.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Materials Chemistry

The decomposition mechanism of p-chloromethylphenyltrimethoxysiloxane (CMPS) self-assembled monolayers (SAMs) due to vacuum ultraviolet (VUV) irradiation at a wavelength of 172 nm has been studied based on water repellency, X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM). The CMPS-SAMs were prepared through chemical vapor deposition at 100°C. The water contact angle increased dramatically within the first 30 min, reaching a plateau at this point. The saturated water contact angle was 76°. Next, the CMPS-SAMs were irradiated at under 10 Pa from 0 to 30 min. The CMPS-SAMs irradiated for 15 and 30 min were covered with carboxylated hydrocarbon fragments and silanol groups, respectively. KPFM measurements for micro-patterned SAMs, i.e. CMPS/CO2H and CMPS/SiOH, showed that the surface potential of the carboxylated and silanol regions were -16 and +19 mV vs. CMPS-SAM, respectively. The former negative surface potential difference originated in the electronegativity of the CO2H fragments. These results provide us with a route to prepare an organic template for various fields such as bio-sensors, chemical sensors and electrolytes.

DOI： 10.1039/b203643f

Surface potential contrasts between silicon surfaces covered and uncovered with an organosilane self-assembled monolayer

Hayashi K., Saito N., Sugimura H., Takai O., Nakagiri N.

Ultramicroscopy Vol. 91 ( 1-4 ) page： 151 - 156 2002.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Ultramicroscopy

Surface potentials of Si substrates covered with a organosilane self-assembled monolayers (SAMs) were measured with reference to the substrate uncovered with the SAM using Kelvin probe force microscopy. Based on a photolithographic technique, the reference surface was prepared in a micrometer scale on each of the samples. SAMs were prepared from n-octadecyltrimethoxysilane [ODS: CH3(CH2)17Si(OCH3)3], 3,3,3-trifluoropropyltrimethoxysilane [FAS3: CF3(CH2)2Si(OCH3)3], heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane [FAS17: CF3(CF2)7(CH2)2Si (OCH3)3] or n-(6-aminohexyl) aminopropyltrimethoxysilane [AHAPS: H2N(CH2)6NH(CH2)3Si (OCH3)3) by chemical vapor deposition. Potentials of the surfaces covered with ODS-, FAS3- and FAS17-SAMs became more negative than the uncovered Si substrate, while the surface covered with AHAPS-SAM showed a more positive surface potential than the reference. The potential contrasts of these SAMs to the reference were -25, -170, -225 and +50mV for ODS-, FAS3-, FAS17- and AHAPS-SAMs, respectively. These results almost agreed with potentials expected from the dipole moments of the corresponding precursor molecules estimated by ab initio molecular orbital calculation, except for FAS3-SAM. Despite FAS3 molecule having a larger dipole moment than FAS17 molecule, the surface potential contrast of FAS3-SAM was smaller than that of FAS17-SAM, since surface coverage of FAS3-SAM was relatively incomplete compared with the other SAMs. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-3991(02)00094-3

Surface potential images of self-assembled monolayers patterned by organosilanes: Ab initio molecular orbital calculations

Saito N., Hayashi K., Sugimura H., Takai O., Nakagiri N.

Surface and Interface Analysis Vol. 34 ( 1 ) page： 601 - 605 2002.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface and Interface Analysis

Self-assembled monolayers (SAMs) with different function terminal groups were prepared on substrates of n-type silicon by chemical vapour deposition (CVD) from n-octadecyltrimethoxysilane (ODS: H3C(CH2)17Si(OCH3)3), heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (FAS: F3C(CF2)7 (CH2)2Si(OCH3)3), n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS: H2N(CH2)6NH(CH2)3 Si(OCH3)3) and 4-(chloromethyl)phenyltrimethoxysilane [CMPS: H2ClC(C6H4)Si(OCH3)3]. The sample surfaces covered with ODS-SAM were irradiated under a reduced pressure of 10 Pa with vacuum ultraviolet (VUV) light through a photomask. Then, the irradiated areas with the ODS-SAM removed were covered with another SAM by CVD. Surface potential images of the patterned areas were measured by Kelvin probe force microscopy (KPFM) and explained by ab initio molecular orbital (MO) calculations. The KPFM measurements showed that the surface potential contrasts of the FAS-, AHAPS- and CMPS-SAMs against the ODS-SAM were about -170, +50 and -30 mV, respectively. The surface potentials as a function of area occupied by a molecule were predicted using the respective dipole moments perpendicular to substrates, which were obtained by the ab initio MO calculations. The predicted surface potentials of the FAS-, CMPS- and AHAPS-SAMs approximately agreed with the measured values at areas of about 1.5, 1.6 and 0.6 nm2 per molecule. The ab initio MO calculations also showed differences in surface potentials appearing due to the differences in Fermi levels of the respective SAMs.

DOI： 10.1002/sia.1369

Surface potential microscopy for organized molecular systems

Sugimura H., Hayashi K., Saito N., Nakagiri N., Takai O.

Applied Surface Science Vol. 188 ( 3-4 ) page： 403 - 410 2002.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Surface Science

Surface potentials of organosilane self-assembled monolayers (SAMs) formed on silicon substrates were measured using Kelvin-probe force microscopy (KFM) employing a SAM formed from n-octadecyltrimethoxysilane [ODS: CH 3 (CH 2 ) 17 Si(OCH 3 ) 3 ] as a reference. The reference ODS surface was prepared in a micrometer scale on each of the samples based on a photolithographic technique using vacuum ultra-violet light at 172 nm. Another SAM was prepared on the same sample surface from heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (fluoroalkylsilane with 17 fluorine atoms, FAS17), 3,3,3-trifluoropropyltrimethoxysilane (fluoroalkylsilane with three fluorine atoms, FAS3), n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS) or (chloromethyl)phenyltrimethoxysilane (CMPS). Potentials of the surfaces covered with FAS17-SAM, FAS3-SAM and CMPS-SAM became more negative than ODS-SAM, while the surface covered with AHAPS-SAM showed a more positive surface potential than the reference. The acquired potential contrasts of the regions covered with FAS17, FAS3, AHAPS and CMPS with reference to ODS were -180, -150, +50 and -30 mV, respectively. These results almost agreed with potentials expected from the dipole moments of the corresponding precursor molecules estimated by ab initio molecular orbital calculation. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0169-4332(01)00958-8

Carbon Nitrides

Takai O., Lee K., Ohta R., Saito N.

Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering Vol. 68 ( 12 ) page： 1526 - 1529 2002

Surface potentials of patterned organosilane self-assembled monolayers acquired by Kelvin probe force microscopy and ab initio molecular calculation

Saito N., Hayashi K., Sugimura H., Takai O., Nakagiri N.

Chemical Physics Letters Vol. 349 ( 3-4 ) page： 172 - 177 2001.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Chemical Physics Letters

This study aimed experimentally and theoretically to reveal the surface potentials of organosilane self-assembled monolayers (SAMs) using Kelvin probe force microscopy (KPFM) and ab initio molecular orbital (MO) calculations, and to distinguish among the surface domains of the SAMs. We prepared the patterned SAMs of n-octadecyltrimethoxysilane [ODS: H3C(CH2)17Si(OCH3)3], heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane [FAS: F3C(CF2)7(CH2) 2Si(OCH3)3] and n-(6-aminohexyl)aminopropyltrimethoxysilane [AHAPS: H2N(CH2)6NH(CH2) 3Si(OCH3)3] by chemical vapor deposition (CVD). The surface potentials for FAS-SAM and AHAPS-SAM vs. ODS-SAM in the atmosphere were -170 and +50 mV, respectively. The experimental surface potentials agreed with the calculated ones at the surface area occupied by a molecule of 1.1-1.5nm2molecule-1. © 2001 Elsevier Science B.V.

DOI： 10.1016/S0009-2614(01)01097-1

Kelvin probe force microscopy images of microstructured organosilane self-assembled monolayers

Sugimura H., Hayashi K., Saito N., Takai O., Nakagiri N.

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers Vol. 40 ( 6 B ) page： 4373 - 4377 2001.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers

A difference in surface potentials between organosilane self-assembled monolayers (SAMs) was measured by means of Kelvin probe force microscopy (KFM). The SAMs were deposited on a single Si substrate from alkylsilane, that is, octadecyltrimethoxysilane (ODS)[H3C(CH2)17Si(OCH3) 3], and fluoroalkylsilane (FAS), that is, heptadecafluoro-1,1,2,2-tetrahydrodecyl-1-trimethoxysilane [F3C(CF2)7(CH2)2 Si(OCH3)3]. The locations of these SAMs on the substrate were defined by means of a photolithographic technique. The regions terminated with ODS and FAS were clearly distinguished by KFM with the surface potential difference between the ODS- and FAS-terminated surfaces under optimized imaging conditions. The surface potential of the FAS-terminated region was 170 ∼ 180 mV lower than the potential of the ODS-terminated surface. The origin of such a low surface potential of FAS-SAM was ascribed to the larger dipole moment of the FAS molecule induced by the electron negativity of F atoms as estimated from a molecular orbital calculation.

DOI： 10.1143/jjap.40.4373

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