Doping of Bi₂Te₃ using electron irradiation

Electron irradiation is investigated as a way to dope the topological insulator Bi₂Te₃. For this, p-type Bi₂Te ₃ single crystals have been irradiated with 2.5 MeV electrons at room temperature and electrical measurements have been performed in situ as well as ex situ in magnetic fields up to 14 T. The defects created by irradiation act as electron donors, allowing the compensation of the initial hole-type conductivity of the material as well as the conversion of the conductivity from p to n type. The changes in carrier concentration are investigated using the Hall effect and Shubnikov-de Haas (SdH) oscillations, clearly observable in the p-type samples before irradiation, but also after the irradiation-induced conversion of the conductivity to n type. The SdH patterns observed for the magnetic field along the trigonal axis can be entirely explained assuming the contributions of only one valence and one conduction band, respectively, and Zeeman splitting of the orbital levels.