  As personal electronic devices increasingly rely on cloud computing for
energy-intensive calculations, the power consumption associated with the
information revolution is rapidly becoming an important environmental issue.
Several approaches have been proposed to construct electronic devices with low
energy consumption. Among these, the low-dissipation surface states of
topological insulators (TIs) are widely employed. To develop TI-based devices,
a key factor is the maximum temperature at which the Dirac surface states
dominate the transport behavior. Here, we employ Shubnikov-de Haas oscillations
(SdH) as a means to study the surface state survival temperature in a high
quality vanadium doped Bi1.08Sn0.02Sb0.9Te2S single crystal system. The
temperature and angle dependence of the SdH show that: 1) crystals with
different vanadium (V) doping levels are insulating in the 3-300 K region, 2)
the SdH oscillations show two-dimensional behavior, indicating that the
oscillations arise from the pure surface states; and 3) at 50 K, the V0.04
single crystals (Vx:Bi1.08-xSn0.02Sb0.9Te2S, where x = 0.04) still show clear
sign of SdH oscillations, which demonstrate that the surface dominant transport
behavior can survive above 50 K. The robust surface states in our V doped
single crystal systems provide an ideal platform to study the Dirac fermions
and their interaction with other materials above 50 K.
