Electrical contact resistances of thermoelectric thin films measured by Kelvin probe microscopy

This work presents an approach for measuring cross plane electrical contact resistances directly using Kelvin Probe Microscopy. With this technique we were able to measure the electrical contact resistances of a cross section of a thermoelectric thin film made of Bi₂Te₃ sandwiched between two gold electrodes. On the one hand, the bottom gold electrode, which is located on top of the silicon substrate, was used as a cathode in electro-deposition process to grow the sample. On the other hand, the gold electrode on top was made via physical evaporation. The electrical contact resistances measured at both interfaces were 0.11 ± 0.01 Ω and 0.15 ± 0.01 Ω, respectively. These differences are related to differences between the top and bottom gold/bismuth-telluride film, obtaining smaller contact resistance where the film was grown by electro-deposition.