Electrical Transport Behavior in Ultra-thin Metallic Films and Nanostructures

  • Amro Alkhatib

Student thesis: Master's Thesis

Abstract

Ultra-thin metallic lms show interesting electrical phenomena as their thickness decreases. In particular, as the thickness reaches the nanoscale their electrical behavior has no precedents in the macroscale since they behave in a non-ohmic fashion. For example, the electrical resistivity of gold, which is a perfect or almost perfect conductor otherwise, can reach values which are orders of magnitude above their macroscale counterparts. Moreover, while the standard ohmic behavior is characterized by a linear relationship between current and voltage, the response of ultra thin ?lms presents non-linearities between the latter that are not taken into account by standard theory. Here, we propose that such behavior is related to the discontinuity in the ?lms below a certain thickness. Such discontinuities appear in lower thicknesses as the metallic lm grows in an island growth mode before they start to merge later on when the thickness grows. As a result of the inherent discontinuity the current cannot and a continuous percolation path in the lateral direction of conduction. Electron tunneling was found to be the dominant mechanism of conduction in such thicknesses. A model for describing this behavior was developed based on Simmon's model for tunneling in MIM junctions. Using that model we showed that two dominant tunneling regimes existed, dependent on the gold island separation and area of tunneling (related to the size of islands). Such interpretation for the observed behavior would be of great importance to enhance the current existing models for electrical conduction in thin metallic ?lms.
Date of AwardDec 2011
Original languageAmerican English

Keywords

  • Electron Transport
  • Acoustic Surface Waves

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