Electrical resistance of metal contact to Bi₂Te₃ based thermoelectric legs

The theoretical aspects of evaluating the electrical resistance of a thermoelectric leg–metal contact are considered. A physical model of such a contact and methods for calculating the main components of the contact resistivity, namely, the resistivity of the interfacial layer and the resistivity related to the transfer of charge carriers through a potential barrier at the boundary between a material of the thermoelectric leg and a metal, are proposed. The contact resistivity for thermoelectric legs made of Bi₂Te₃ based materials with deposited antidiffusion nickel layers is calculated. It was established that the contact resistivity in such thermoelements reaches a value from 0.25 × 10⁻⁶ to 2.5 × 10⁻⁶ Ω cm² and depends on the temperature and interfacial layer thickness. It is demonstrated that the findings are in good agreement with the known experimental values of contact resistivity.