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We report that Bi₂Se₃ thin films can be epitaxially grown on SrTiO₃ substrates, which allow for very large tunablity in carrier density with a back gate. The observed low field magnetoconductivity due to weak antilocalization (WAL) has a very weak gate-voltage dependence unless the electron density is reduced to very low values. Such a transition in WAL is correlated with unusual changes in longitudinal and Hall resistivities. Our results suggest a much suppressed bulk conductivity at large negative gate voltages and a possible role of surface states in the WAL phenomena.

Growth mechanisms of ZnO(0001) investigated using the first-principles calculation J. Appl. Phys. 112, 064301 (2012) Generation of silver-anatase nanocomposite by excimer laser-assisted processing AIP Advances 2, 032171 (2012) Degradation and passivation of CuInSe2

We demonstrate that the weak antilocalization effect can serve as a convenient method for detecting decoupled surface transport in topological insulator thin films. In the regime where a bulk Fermi surface coexists with the surface states, the low field magnetoconductivity is described well by the Hikami-Larkin-Nagaoka equation for single component transport of non-interacting electrons. When the electron density is lowered, the magnetotransport behavior deviates from the single component description and strong evidence is found for independent conducting channels at the bottom and top surfaces. Magnetic-field-dependent part of corrections to conductivity due to electron-electron interactions is shown to be negligible for the fields relevant to weak antilocalization.