High-Mobility Ambipolar Magnetotransport in Topological Insulator <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> Nanoribbons

Nanoribbons of topological insulators (TIs) have been suggested for a variety applications exploiting the properties topologically protected surface Dirac states. In these proposals it is crucial to achieve high tunability Fermi energy, through point while preserving mobility involved carriers. Tunable transport in TI nanoribbons has achieved by chemical doping materials so reduce bulk carriers' concentration, however at expense electrons, which substantially reduced. Here we study bare ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ transferred on oxide substrates and demonstrate that use large relative permittivity ${\mathrm{Sr}\mathrm{Ti}\mathrm{O}}_{3}$ substrate enables energy be tuned an ambipolar field effect obtained. Through magnetotransport Hall conductance measurements, performed single nanoribbons, electron hole carriers are exclusively high-mobility without any contribution. The allows therefore easy gating nanostructures providing ideal platform take advantage