Growth of High-Mobility
Bi<sub>2</sub>Te<sub>2</sub>Se Nanoplatelets on hBN Sheets by van
der Waals Epitaxy
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Abstract
The electrical detection of the surface states of topological
insulators
is strongly impeded by the interference of bulk conduction, which
commonly arises due to pronounced doping associated with the formation
of lattice defects. As exemplified by the topological insulator Bi<sub>2</sub>Te<sub>2</sub>Se, we show that via van der Waals epitaxial
growth on thin hBN substrates the structural quality of such nanoplatelets
can be substantially improved. The surface state carrier mobility
of nanoplatelets on hBN is increased by a factor of about 3 compared
to platelets on conventional Si/SiO<sub><i>x</i></sub> substrates,
which enables the observation of well-developed Shubnikov-de Haas
oscillations. We furthermore demonstrate the possibility to effectively
tune the Fermi level position in the films with the aid of a back
gate