  Based on the interface polarization model, the two-dimensional electron gas
(2DEG) at $LaInO_{3}$(LIO)/$BaSnO_{3}$(BSO) interfaces is understood to
originate from a polarization discontinuity at the interface and the conduction
band offset between LIO and BSO. In this scenario, the direction of
polarization at the interface is determined by whether the first atomic LIO
layer at the interface is LaO$^{+}$ or InO$_{2}^{-}$. We investigate the role
of the terminating layer at the LIO/BSO interface in creating the 2DEG. Based
on conductance measurements of our in-situ grown LIO/BSO heterostructures, we
report in this work that the 2DEG only forms when the BSO surface is terminated
with a SnO$_{2}$ layer. We controlled the terminating layer by additional
SnO$_{2}$ deposition on the BSO surface. We show that the as-grown BSO surface
has a mixed terminating layer of BaO and SnO$_{2}$ while the BSO surfaces
prepared with additional SnO$_{2}$ deposition are terminated mainly with the
SnO$_{2}$ layer. The terminating layer was confirmed by coaxial impact
collision ion scattering spectroscopy (CAICISS). Our finding is consistent with
the interface polarization model for 2DEG formation at LIO/BSO interfaces, in
which the direction of the interfacial polarization in LIO is determined by the
terminating layer of the BSO surface.
