Low temperature bonding process for Bi₂Te₃/Si heterojunctions

The bonding between Bi₂Te₃ and Si wafers is prepared under low temperature through forming Si-O-Te and Si-O-Bi. Under the irradiation of vacuum ultraviolet, oxygen radicals and ozone are formed from oxygen molecules, which produces the thin oxide layers on the wafers’ surfaces. By absorbing water molecules and by dehydration-condensation reaction, the bonds of Si-O-Te and Si-O-Bi are formed. During the annealing process, Te atoms more easily diffuse into Si wafers than Bi atoms because the surface of Bi₂Te₃ is terminated with Te atoms. The layered crystal structure of Bi₂Te₃ weakens the bonding strength because only the surface layer of Bi₂Te₃ can bond with Si. The fabricated Bi₂Te₃/Si heterojunctions have the typical I-V curve of PN junctions.