Studies on surface preparation and smoothness of nanostructured Bi2Te3-based alloys by electrochemical and mechanical methods

Significant improvements in the dimensionless thermoelectric figure-of-merit (ZT) for nanostructured bismuth telluride, Bi₂Te₃, and its alloys have been demonstrated. In designing high-performance thermoelectric devices, variations in the thermal and electrical contact resistances due to interfacial effects between the nanostructured alloy and the metallic electrodes remain a significant issue. Smooth scratch-free surfaces should provide a baseline for contact resistance studies. In this paper, the root mean square roughness over a 10 μm² of nanostructured bismuth tellurium based alloys was reduced from 133 nm to 1.9 nm by a procedure consisting of electrolysis, mechanical polishing, and chemical mechanical polishing (CMP). Post-CMP cleaning was also developed to yield a wettable surface for the subsequent conformable metallization.