Sandrine Rivillon

Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States

Are you Sandrine Rivillon?

Claim your profile

Publications (16)38.58 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: In this work, the vibrations of mixed coverage Si(111)−H/Cl surfaces are determined using quantum chemical calculations and Fourier transform infrared spectroscopy. The structure and symmetry considerations of the modes are used to assign the vibrational frequencies for varying coverages of both hydrogen and chlorine on the surface. Significant shifts in the Si−H and Si−Cl stretching frequencies are found as a function of coverage, while the bending modes are shifted very slightly. Our results suggest that Si−H stretching shifts can be used as a probe for chlorine coverage during the reaction of chlorine precursors with the hydrogen-terminated Si(111) surface. Finally, an analysis of coverage dependence suggests that a chemical inductive effect is the dominant origin of the resulting stretching frequency shifts, though a small contribution from the lone pairs interacting with the surface is also possible.
    Journal of Physical Chemistry C - J PHYS CHEM C. 12/2009; 113(52).
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: We demonstrate methodologies to improve the interface characteristics between a germanium (Ge) substrate and high-k gate dielectrics. GeON and SiOx were investigated as passivating layers on a Ge surface. Smaller hysteresis and interface state density (Dit) were obtained using SiOx interface layer and p-type metal oxide semiconductor field effect transistors (MOSFETs) fabricated with a gate stack of Ge/SiOx/HfSiO/WN showed about two times higher effective mobility compared to universal Si/SiO2 MOSFET. Because the formation of GeOx at the interface resulted in higher hysteresis and equivalent oxide thickness, the effective suppression of growth of unstable GeOx by SiOx interface layer contributed to the good device characteristics of the fabricated devices.
    Applied Physics Letters 01/2008; 93. · 3.79 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Anti-relaxation surface coatings eliminate the need for buffer gas in alkali-metal vapor cells, giving larger signals due to narrower optical linewidths as well as reduced sensitivity to magnetic field gradients. Paraffin and other coatings presently used to reduce surface relaxation typically cannot operate at the high temperatures (T>100^oC for cesium and T>150^oC for potassium) required to obtain alkali-metal density suitable for spin-exchange relaxation free (SERF) magnetometers. We have found that octadecyltrichlorosilane (OTS) coating can allow approximately 2000 collisions of a potassium atom with the cell walls before depolarization. OTS can operate at temperatures of at least 150^oC in the presence of potassium, and we have demonstrated a SERF magnetometer using an OTS-coated cell. We have also developed a reusable alkali vapor cell for simultaneous testing of multiple coated surfaces, and we are presently investigating several other coatings for chemical resistance to alkali metals, antirelaxation properties, and high-temperature operation. Development of a robust, high-temperature anti-relaxation surface coating would allow many experiments using very optically thick alkali vapor with a long spin relaxation time.
    01/2007;
  • [show abstract] [hide abstract]
    ABSTRACT: Fourier transform infrared spectroscopy and first principles calculations have been used to investigate the reaction of atomically smooth, hydrogen-terminated Si(111) (H-Si) surfaces with anhydrous liquid methanol. After 10 min of reaction at room temperature, a sharp absorbance feature was apparent at approximately 1080 cm(-1) that was polarized normal to the surface plane. Previous reports have identified this mode as a Si-O-C stretch; however, the first principles calculations, presented in this work, indicate that this mode is a combination of an O-C stretch with a CH3 rock. At longer reaction times, the intensity of the Si-H stretching mode decreased, while peaks attributable to the O-C coupled stretch and the CH3 stretching modes, respectively, increased in intensity. Spectra of H-Si(111) surfaces that had reacted with CD3OD showed the appearance of Si-D signals polarized normal to the surface as well as the appearance of vibrations indicative of Si-OCD3 surface species. The data are consistent with two surface reactions occurring in parallel, involving (a) chemical attack of hydrogen-terminated Si(111) terraces by CH3OH, forming Si-OCH3 moieties having their Si-O bond oriented normal to the Si(111) surface and (b) transfer of the acidic hydrogen of the methanol to the silicon surface, either through a direct H-to-D exchange mechanism or through a mechanism involving chemical step-flow etching of Si-H step sites.
    The Journal of Physical Chemistry B 11/2006; 110(41):20426-34. · 3.61 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This version is available at the following Publisher URL: http://apl.aip.org
    Applied Physics Letters 08/2006; · 3.79 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Transmission infrared spectroscopy (TIRS) has been used to investigate the surface-bound species formed in the two-step chlorination/alkylation reaction of crystalline (111)-oriented Si surfaces. Spectra were obtained after hydrogen termination, chlorine termination, and reaction of the Cl-Si(111) surface with CH(3)MgX or C(2)H(5)MgX (X = Cl, Br) to form methyl (CH(3))- or ethyl (C(2)H(5))-terminated Si(111) surfaces, respectively. Freshly etched H-terminated Si(111) surfaces that were subsequently chlorinated by immersion in a saturated solution of PCl(5) in chlorobenzene were characterized by complete loss of the Si-H stretching and bending modes at 2083 and 627 cm(-1)(,) respectively, and the appearance of Si-Cl modes at 583 and 528 cm(-1). TIRS of the CH(3)-terminated Si(111) surface exhibited a peak at 1257 cm(-1) polarized perpendicular to the surface assigned to the C-H symmetrical bending, or "umbrella" motion, of the methyl group. A peak observed at 757 cm(-1) polarized parallel to the surface was assigned to the C-H rocking motion. Alkyl C-H stretch modes on both the CH(3)- and C(2)H(5)-terminated surfaces were observed near 2900 cm(-1). The C(2)H(5)-terminated Si(111) surface additionally exhibited broad bands at 2068 and 2080 cm(-1), respectively, polarized perpendicular to the surface, as well as peaks at 620 and 627 cm(-1), respectively, polarized parallel to the surface. These modes were assigned to the Si-H stretching and bending motions, respectively, resulting from H-termination of surface atoms that did not form Si-C bonds during the ethylation reaction.
    The Journal of Physical Chemistry B 05/2006; 110(14):7349-56. · 3.61 Impact Factor
  • The 2006 Annual Meeting. 01/2006;
  • S. Rivillon, Y. J. Chabal
    [show abstract] [hide abstract]
    ABSTRACT: Methylation of chlorine-terminated silicon (111) (Si-Cl) is investigated by Infra Red Absorption Spectroscopy (IRAS). Starting from an atomically flat H-terminated Si(111), the surface is first chlorinated by a gas phase process, then methylated using a Grignard reagent. Methyl groups completely replace Cl, and are oriented normal to the surface. The surface remains atomically flat with no evidence of etching.
    Journal de Physique IV (Proceedings) 01/2006; 132:195-198. · 0.29 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This paper describes the challenges faced by the microelectronics community in growing ultra-thin films using Atomic Layer Deposition and summarizes how mechanistic information derived from in situ infrared absorption spectroscopy studies can guide the growth of sub-nanometer films. Examples are drawn from the growth of high-k dielectrics (e.g. HfO2 ) on oxide-free silicon surfaces to achieve the lowest effective oxide thickness.
    01/2006;
  • Sandrine Rivillon, Yves J. Chabal, Fabrice Amy, Antoine Kahn
    [show abstract] [hide abstract]
    ABSTRACT: A wet chemical preparation involving de-ionized water, hydrogen peroxide, and hydrofluoric acid is used to passivate germanium (Ge) (100) surfaces. Infrared absorption spectroscopy and x-ray photoemission spectroscopy studies show that oxide free and hydrogen-terminated Ge (100) surfaces can be obtained. As in the case for silicon (100) surfaces etched in hydrofluoric acid, hydrogen-terminated Ge (100) surfaces are atomically rough, with primarily mono- and dihydride terminations.
    Applied Physics Letters 12/2005; 87(25):253101-253101-3. · 3.79 Impact Factor
  • Sandrine Rivillon, Rhett T. Brewer, Yves J. Chabal
    [show abstract] [hide abstract]
    ABSTRACT: Hydroxylation of chlorine-terminated silicon (111) and (100) by water vapor exposure has been studied as a function of substrate temperature using in situ infrared absorption spectroscopy. No hydroxyl is observed, as would have been expected from the surface reaction: Si – Cl <sub>( ads )</sub>+ H <sub>2</sub> O <sub>(g)</sub>→ Si – OH <sub>( ads )</sub>+ HCl <sub>(g)</sub> (ads referring to adsorbed surface species). Instead, silicon oxide is formed upon removal of the Si–Cl bond at ∼325 ° C . This indicates that, while hydroxylation of the Cl-terminated silicon surface may occur, the hydroxylated surface formed by this reaction is not stable at the temperature necessary for the reaction.
    Applied Physics Letters 11/2005; · 3.79 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Immobilization of indene ligands onto two types of hydrogen-terminated surfaces, oxide-free Si [H/Si(111)] and oxidized Si [H/SiO2/Si], has been investigated by infrared absorption spectroscopy. The activity of a common catalyst (H2PtCl6) is shown to depend critically on the nature of the solvent. For instance, 2-propanol preferentially reacts with the surface, preventing any ligand attachment. Chlorobenzene is more stable, allowing some ligand attachment, but the H2PtCl6 catalyst also fosters silicon oxidation. In contrast, UV irradiation on oxide-free surfaces promotes a cleaner and more efficient reaction, leading to ligand attachment without substrate oxidation. The complete inactivity of H-terminated surfaces with a thin oxide layer [H/SiO2/Si] suggests that the UV-induced immobilization is mediated solely by the excitation of electron-hole pairs (excitons) in the substrate and is not the result of direct Si-H bond breaking.
    Journal of the American Chemical Society 10/2005; 127(37):12798-9. · 10.68 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Infrared absorption spectroscopy was used to investigate the chlorination of hydrogen-terminated Si(111) surfaces by three different methods: (a) exposure to a saturated solution of phosphorus pentachloride (PCl5) in chlorobenzene; (b) exposure to chlorine gas, Cl2(g), and (c) exposure to Cl2(g) under UV illumination. X-ray photoelectron spectroscopy and first principles model (clusters) calculations were used to explore the structure and dynamics of these surfaces. The infrared spectra exhibited sharp chlorine-related vibrations at 586 and 527 cm^–1. The narrow full width at half maximum of these vibrations for all three preparation methods indicated that all functionalization schemes produced a nearly complete monolayer of Cl with little surface roughening or introduction of step edges. The 527 cm^–1 mode was at a much higher frequency than might be expected for the bending vibration of Si monochloride. Theoretical calculations show, however, that this vibration involves the displacement of the top Si atom parallel to the surface, subject to a relatively stiff potential, shifting its frequency to a value fairly close to that of the Si–Cl stretching mode on a Si(111) surface.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2005; · 1.43 Impact Factor
  • Solid State Phenomena. 01/2005;
  • [show abstract] [hide abstract]
    ABSTRACT: We report the structure of 5,5′-bis(4-hydroxyhexylphenyl)-2,2′-bithiophene (HO6PTTP60H) powder and sublimated films studied by X-ray diffraction (XRD) and Infrared absorption spectroscopy (IRAS). From XRD, herringbone packing is observed for the HO6PTTP60H powder. Different layer spacing is found for the powder (33.1Å) and the sublimated film (26.5Å). This slight difference indicates that the HO6PTTP60H molecule is tilted in the film. IRAS results confirm the presence of the HO6PTTP6OH molecule on the surface and its good stability over a few days.
    Materials Research Society; 01/2005
  • [show abstract] [hide abstract]
    ABSTRACT: A simple method is described to functionalize hydrogen-passivated Si(111) and Si(100) surfaces with chlorine (Cl2) gas. Infrared-absorption spectroscopy provides a positive identification of chlorination and mechanistic information on the chlorination of H-terminated Si surfaces, and on the structure and stability of chlorine-terminated Si surfaces (Cl∕Si). We find that the chlorination process does not change the surface morphology: H∕Si(111)‐(1×1) surfaces and HF-etched Si(100) surfaces remain atomically flat and atomically rough, respectively, upon chlorination. Chlorinated S: surfaces are stable in a nitrogen atmosphere for over 12 hours.
    Applied Physics Letters 09/2004; 85(13):2583-2585. · 3.79 Impact Factor