  The prospect of 2-dimensional electron gases (2DEGs) possessing high mobility
at room temperature in wide-bandgap perovskite stannates is enticing for oxide
electronics, particularly to realize transparent and high-electron mobility
transistors. Nonetheless only a small number of studies to date report 2DEGs in
BaSnO3-based heterostructures. Here, we report 2DEG formation at the
LaScO3/BaSnO3 (LSO/BSO) interface with a room-temperature mobility of 60 cm2/V
s at a carrier concentration of 1.7x1013 cm-2. This is an order of magnitude
higher mobility at room temperature than achieved in SrTiO3-based 2DEGs. We
achieved this by combining a thick BSO buffer layer with an ex-situ
high-temperature treatment, which not only reduces the dislocation density but
also produces a SnO2-terminated atomically flat surface, followed by the growth
of an overlying BSO/LSO interface. Using weak-beam dark field imaging and
in-line electron holography technique, we reveal a reduction of the threading
dislocation density, and provide direct evidence for the spatial confinement of
a 2DEG at the BSO/LSO interface. Our work opens a new pathway to explore the
exciting physics of stannate-based 2DEGs at application-relevant temperatures
for oxide nanoelectronics.
