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Molecular Modulation of Conductivity on H-Terminated Silicon-On-Insulator Substrates

Authors

  • Girjesh Dubey,

    1. Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada
    2. INRS-EMT, Université du Québec, 1650 boul. Lionel-Boulet, Varennes, Quebec, J3X 1S2, Canada
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  • Federico Rosei,

    1. INRS-EMT, Université du Québec, 1650 boul. Lionel-Boulet, Varennes, Quebec, J3X 1S2, Canada
    2. Center for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montréal, Québec, H3A 2K6, Canada
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  • Gregory P. Lopinski

    Corresponding author
    1. Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada
    • Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada.
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Abstract

The adsorption of a range of molecular species (water, pyridine, and ammonia) is found to reversibly modulate the conductivity of hydrogen-terminated silicon-on-insulator (H-SOI) substrates. Simultaneous sheet-resistance and Hall-effect measurements on moderately doped (1015 cm−3) n- and p-type H-SOI samples mounted in a vacuum system are used to monitor the effect of gas exposure in the Torr range on the electrical-transport properties of these substrates. Reversible physisorption of “hole-trapping” species, such as pyridine (C5H5N) and ammonia (NH3) produces highly conductive minority-carrier channels (inversion) on p-type substrates, mimicking the action of a metallic gate in a field-effect transistor. The adsorption of these same molecules on n-type SOI induces strong electron-accumulation layers. Minority/majority channels are also formed upon controlled exposure to water vapor. These observations can be explained by a classical band-bending model, which considers the adsorbates as the source of a uniform surface charge ranging from +1011 to +1012q cm−2. These results demonstrate the utility of DC transport measurements of SOI platforms for studies of molecular adsorption and charge-transfer effects at semiconductor surfaces.

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