  We have demonstrated few-electron quantum dots in Si/SiGe and InGaAs, with
occupation number controllable from N = 0. These display a high degree of
spatial symmetry and identifiable shell structure. Magnetospectroscopy
measurements show that two Si-based devices possess a singlet N =2 ground state
at low magnetic field and therefore the two-fold valley degeneracy is lifted.
The valley splittings in these two devices were 120 and 270 {\mu}eV, suggesting
the presence of atomically sharp interfaces in our heterostructures.
