Barrier parameter variation in Al-Al2O3-metal tunnel junctions

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Abstract
A trapezoidal potential barrier was used to model an Al2O3 barrier layer in three different tunnel junctions: Al‐Al2O3‐Au, ‐Ag and ‐Cu. The trapezoidal tunneling barrier parameters were determined by fitting the calculated I‐V curves to the experimental curves at 77 K. It is found that the barrier width of the Au‐, Ag‐, and Cu‐junction is 24, 25, and 12 Å, respectively, and that the barrier heights of the three different junctions are close to each other at the Al‐Al2O3 interface, but they are 1.05, 0.85, and 3.10 eV at the Al2O3‐Au, ‐Ag, and ‐Cu interface, respectively. The Auger depth profiles of the junctions suggest that the variation of the barrier parameters with the top electrode may be due to diffusion of the top electrode atoms into the barrier and the occurrence of the oxidation reaction between the Al2O3 and the top metal electrode atoms in the region of the interfaces.