Optical response of metal–insulator–metal heterostructures and their application for the detection of chemicurrents

  • Autor:

    Thissen, P. / Schindler, B. / Diesing, D. / Hasselbrink, E. (2010)
  • Quelle:

    New Journal of Physics 12 (2010)
  • Datum: 2010

  • Thissen, P. / Schindler, B. / Diesing, D. / Hasselbrink, E. (2010): „Optical response of metal–insulator–metal heterostructures and their application for the detection of chemicurrents “. In: New Journal of Physics 12 (2010)

Abstract

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The optical response of thin-film metal–insulator–metal (MIM) systems of tantalum–tantalum oxide–Au type is studied by recording the macroscopic current across the device resulting from the low-energy electron–hole pairs excited in the metals by red and near-infrared (NIR) light (hν<2 eV).

It is observed that current flows from the top Au to the back Ta electrode, although a larger number of photons is absorbed in the latter. This directional preference is attributed to the built-in electric field across the oxide layer. The yield per photon increases strongly as photon energy becomes comparable to the barrier height. Current exhibits a strong dependence on bias voltages applied across the oxide layer.

Photoyields induced by NIR light (hν~1.5 eV) were found to be comparable to recently observed chemicurrents arising from exposure of a MIM sensor to atomic hydrogen, when compared on a current per photon to current per impinging hydrogen atom basis.