AVS 53rd International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuA

Paper NS-TuA8
Catalytic Nanodiode; Chemical Sensing of Gas Phase Catalytic Reaction by using Hot Electron Flows at Metal-Oxide Interface

Tuesday, November 14, 2006, 4:20 pm, Room 2016

Session: Nanoscale Devices and Detection
Presenter: J.Y. Park, University of California, Lawrence Berkeley National Laboratory
Authors: J.Y. Park, University of California, Lawrence Berkeley National Laboratory
J.R. Renzas, University of California, Berkeley
A.M. Contreras, University of California, Berkeley
G.A. Somorjai, University of California, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
Atomic or molecular processes in metals can generate a pulse of hot electrons with kinetic energy of 1-3 eV, and mean free path of the range of ~10 nm. The flow of these hot electrons are directly measured during the platinum catalyzed oxidation of carbon monoxide across a Pt-TiO@sub 2@ and Pt-GaN Schottky nanodiode that were constructed from Pt film, oxide layers, and Ohmic contact pads. The thickness of Pt film used as the catalyst was 5 nm, less than the electron mean free path, resulting in the ballistic transport of hot electrons through the metal. By heating the nanodiodes in He, we could measure the thermoelectric current that is in the opposite direction to the flow of the hot electron current. We found that the chemicurrent was well correlated with the turnover rate of CO oxidation separately measured by gas chromatography, suggesting the possibility of application as chemical sensors with high sensitivity. Chemicurrent measured through the metal-oxide interface remains stable for over several hours and is reversible upon temperature change. The influence of the flow of hot charge carriers on the chemistry at the oxide-metal interface and the turnover rate in the chemical reaction will be discussed.