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arXiv · 1006.2436

Ex-situ Tunnel Junction Process Technique Characterized by Coulomb Blockade Thermometry

M. Prunnila·M. Meschke·D. Gunnarsson·S. Enouz-Vedrenne·J. M. Kivioja·J. P. Pekola
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Abstract

We investigate a wafer scale tunnel junction fabrication method, where a plasma etched via through a dielectric layer covering bottom Al electrode defines the tunnel junction area. The ex-situ tunnel barrier is formed by oxidation of the bottom electrode in the junction area. Room temperature resistance mapping over a 150 mm wafer give local deviation values of the tunnel junction resistance that fall below 7.5 % with an average of 1.3 %. The deviation is further investigated by sub-1 K measurements of a device, which has one tunnel junction connected to four arrays consisting of N junctions (N = 41, junction diameter 700 nm). The differential conductance is measured in single-junction and array Coulomb blockade thermometer operation modes. By fitting the experimental data to the theoretical models we found an upper limit for the local tunnel junction resistance deviation of ~5 % for the array of 2N+1 junctions. This value is of the same order as the minimum detectable deviation defined by the accuracy of our experimental setup.

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M. Prunnila, M. Meschke, D. Gunnarsson, S. Enouz-Vedrenne, J. M. Kivioja, J. P. Pekola. 2010-06-12. Ex-situ Tunnel Junction Process Technique Characterized by Coulomb Blockade Thermometry. https://doi.org/10.1116/1.3490406

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