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.