. Test curves of contact resistances between BT-x(x=2 (a), 4 (b), 6 (c), 8(d), 10 (e)) materials and Ni barrier layers, and (f) histogram of contact resistance for BT-x

. Interface bonding strength test

. Digital photos of BT-4 sample before (a1) and after (a2) corrosion, optical microstructures of BT-x(x=2 (b1), 4 (b2), 6 (b3), 8 (b4), 10 (b5)) surfaces, and (c) histogram of roughness for BT-x

. Microstructures of material interfaces between BT-x(x=2 (a1-a3), 4 (b1-b3), 6 (c1-c3), 8 (d1-d3), 10 (e1-e3)) and Ni barrier layers

. (a) Fine microstructure of the interface between BT-4 material and Ni layer, (b) partially enlarged image and corresponding (c1) Bi, (c2) Ni, (c3) Se, (c4) Te surficial elemental distribution mappings, and (d) schematic diagram of interface structure between BT-4 material and Ni barrier layer

. Performance of micro thermoelectric device

Table 1. Contact resistance and tensile bonding strength parameters of n-type Bi₂Te₃ barrier layers