A Resistivity Model for Ultrathin Films and Sensors

    Authors

    R. C. Youngquist; M. A. Nurge; B. H. Fisher;D. C. Malocha

    Comments

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    Abbreviated Journal Title

    IEEE Sens. J.

    Keywords

    Conductivity; gold thin films; modeling; palladium thin films; thin film; modeling; thin films; thin film hydrogen sensors; thin film sensors; titanium thin films; ultra-thin films; DISCONTINUOUS PALLADIUM FILMS; ELECTRICAL-CONDUCTION; METAL-FILMS; POLYCRYSTALLINE FILMS; HYDROGEN ABSORPTION; RESISTANCE; Engineering, Electrical & Electronic; Instruments & Instrumentation; Physics, Applied

    Abstract

    Gas sensors have been demonstrated based on the conductivity changes in ultrathin films. These sensors operate in a regime where three different physical phenomena determine the total resistivity of the film; quantum mechanical coupling between metallic islands, bulk material conductivity of the islands, and network resistivity. We present a lumped parameter model that simulates thin-film growth and calculates the total film resistance during the growth process accounting for these three phenomena. The model contains four free parameters and yields a good agreement with experimental data presented for palladium, titanium, and gold. The primary benefit of this model is that it shows the relative contribution of each source of conductivity during the growth process providing insight into the operation of ultrathin films as gas sensors. We then model an ultrathin-film palladium-based hydrogen sensor and show that the sensing mechanism is primarily due to variations in quantum tunneling.

    Journal Title

    Ieee Sensors Journal

    Volume

    15

    Issue/Number

    4

    Publication Date

    1-1-2015

    Document Type

    Article

    Language

    English

    First Page

    2412

    Last Page

    2418

    WOS Identifier

    WOS:000349780000010

    ISSN

    1530-437X

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