Lattice location and electrical conductivity in Sb-implanted rutile

Single crystals of ${\mathrm{TiO}}_2$ (rutile) were implanted with Sb ions applying fluences of 2×${10}^{13}$/${\mathrm{cm}}^2$ to 5×${10}^{16}$/${\mathrm{cm}}^2$ at 300 keV. The lattice location together with the ion range and damage distribution was measured using Rutherford-backscattering and channeling. The conductivity was measured as a function of temperature in the region between 6 and 300 K. Up to a dose of 5×${10}^{15}$/${\mathrm{cm}}^2$ the Sb atoms were entirely substitutional on Ti sites as concluded from channeling measurements on 〈001〉- and 〈100〉-oriented ${\mathrm{TiO}}_2$ single crystals. A large increase of the conductivity σ was observed with increasing Sb dose, indicating a saturation behavior at about 30 ${\mathrm{\Omega }}^{\mathrm{-}1}$ ${\mathrm{cm}}^{\mathrm{-}1}$. Between 40 and 293 K ln σ was proportional to ${\mathrm{T}}^{\mathrm{-}1\mathrm{/}2}$ for low doses, and proportional to ${\mathrm{T}}^{\mathrm{-}1\mathrm{/}4}$ for doses of 1×${10}^{16}$ Sb/${\mathrm{cm}}^2$ and above, indicating that the transport mechanism is due to variable range hopping.