Effects of Heavy Deformation and Annealing on the Electrical Properties of Bi₂Te₃ Available to Purchase

Heavy plastic deformation producing nonbasal slip in Bi₂Te₃ changes the material from p type to n type and decreases its resistivity. From Hall coefficient measurements, it appears that an excess of about 2×10²⁰ negative carriers can be generated in the lattice. Annealing the deformed samples at different temperatures and in different environments causes large changes in this excess carrier concentration. A simple theoretical model based on point defect generation by the plastic deformation accounts for the results. From this model, it appears that tellurium vacancies are the predominant electrically active point defects. These Te vacancies are annihilated by dislocation climb and array formation during annealing. The effect of dissolved oxygen in Bi₂Te₃ is to add donor states to the system.