Abstract
Bi2(Te,Se)3 and (Bi,Sb)2Te3 are important for thermoelectric applications, and Sn is the major element for most of the electronic solders. Interfacial reactions in the Sn/Bi2Te3, Sn/Bi2Se3, Sn/Sb2Te3, Sn/Bi2(Te1-xSex)3 and Sn/(Bi0.25Sb0.75)2Te3 couples are examined at 250oC. The reaction phase, SnTe, is found in all the couples containing Te, and its growth rates are very fast. An interesting Sn3Sb2/SnTe alternating layer microstructure is found in the Sn/(Bi0.25Sb0.75)2Te3 and Sn/Sb2Te3 couples reacted for longer than 15 minutes. In the Sn/Bi2Te3 couple, the reaction zone is non-planar and SnTe is the reaction product. The reaction layers are planar in both the Sn/Bi2Se3 and Sn/Bi2(Te1-xSex)3 couples. The reaction path is Liquid/(SnSe+Bi)/ SnSe/BiSe/Bi2Se3 in the Sn/Bi2Se3 couple, and there are two SnSe phases with different Bi contents. With only 2.0at%Se addition into the Bi2Te3 substrate, very different reaction results are observed in the Sn/Bi2(Te1-xSex)3 couple. The reaction path is Liquid/SnTe/BiTex/ Bi2(Te1-xSex)3.