  Epitaxial La doped BaSnO3 films were grown in an adsorption controlled regime
by molecular beam epitaxy, where the excess volatile SnOx desorbs from the film
surface. A film grown on a (001) DyScO3 substrate exhibited a mobility of 183
cm^2 V^-1 s^-1 at room temperature and 400 cm^2 V^-1 s^-1 at 10 K, despite the
high concentration (1.2x10^11 cm^-2) of threading dislocations present. In
comparison to other reports, we observe a much lower concentration of (BaO)2
Ruddlesden Popper crystallographic shear faults. This suggests that in addition
to threading dislocations that other defects possibly (BaO)2 crystallographic
shear defects or point defects significantly reduce the electron mobility.
