Fe-Ni-Cr diffusion barrier for high-temperature operation of Bi2Te3

Bismuth-telluride (Bi ₂Te ₃ )-based thermoelectric modules are widely used in practical applications at room temperature. However, to enable the utilization of waste heat sources, Bi ₂Te ₃ -based thermoelectric modules need to operate at high efficiency levels over a medium temperature range (200–250 °C). To achieve high efficiency of Bi ₂Te ₃ modules operating at this temperature range, an optimal metallization layer should be inserted to minimize the electrical and thermal contact resistance and prevent elemental diffusion at the interface. In this work, we suggest a novel Fe-Ni-Cr layer to overcome the poor performance of the Ni layer, which is currently widely used as a metallization layer. The proposed Fe-Ni-Cr metallization resulted in a strong enough interface structure without any detachment even after thermal aging whereas the Ni-Cr metallization suffered from layer detachment problems. The specific electrical contact resistance of Fe-Ni-Cr metallization showed minor increase and remains at the ∼10 ⁻⁵ Ω·cm ² level after thermal aging at 250 ℃ for 100 h. The reliability of the Fe-Ni-Cr metallization layer was demonstrated with a 32-couples thermoelectric module, which showed a 5 % enhancement compared to Ni metallization thermoelectric module.