Interface Microstructure and Performance of Sb Contacts in Bismuth Telluride-Based Thermoelectric Elements

A thermoelectric joint composed of p-type Bi0.5Sb1.5Te3 (BiSbTe) material and an antimony (Sb) interlayer was fabricated by spark plasma sintering. The reliability of the thermoelectric joints was investigated using electron probe microanalysis for samples with different accelerated isothermal aging time. After aging for 30 days at 300A degrees C in vacuum, the thickness of the diffusion layer at the BiSbTe/Sb interface was about 30 mu m, and Sb2Te3 was identified to be the major interfacial compound by element analysis. The contact resistivity was 3 x 10(-6) ohm cm(2) before aging and increased to 8.5 x 10(-6) ohm cm(2) after aging for 30 days at 300A degrees C, an increase associated with the thickness of the interfacial compound. This contact resistivity is very small compared with that of samples with solder alloys as the interlayer. In addition, we have also investigated the interface behavior of Sb layers integrated with n-type Bi2Se0.3Te2.7 (BiSeTe) material, and obtained similar results as for the p-type semiconductor. The present study suggests that Sb may be useful as a new interlayer material for bismuth telluride-based power generation devices.