  To improve mobility of fabricated silicon metal-oxide-semiconductor (MOS)
quantum devices, forming gas annealing is a common method used to mitigate the
effects of disorder at the Si/SiO2 interface. However, the importance of
activation annealing is usually ignored. Here, we show that a high vacuum
environment for implantation activation is beneficial for improving mobility
compared to nitrogen atmosphere. Low-temperature transport measurements of Hall
bars show that peak mobility can be improved by a factor of two, reaching 1.5
m^2/(Vs) using high vacuum annealing during implantation activation. Moreover,
the charge stability diagram of a single quantum dot is mapped, with no visible
disturbance caused by disorder, suggesting possibility of fabricating
high-quality quantum dots on commercial wafers. Our results may provide
valuable insights into device optimization in silicon-based quantum computing.
