  We perform quantum Hall measurements on three types of commercially available
modulation doped Si/SiGe heterostructures to determine their suitability for
depletion gate defined quantum dot devices. By adjusting the growth parameters,
we are able to achieve electron gases with charge densities 1-3 X 10^{11}/cm^2
and mobilities in excess of 100,000 cm^2/Vs. Double quantum dot devices
fabricated on these heterostructures show clear evidence of single charge
transitions as measured in dc transport and charge sensing and exhibit electron
temperatures of 100 mK in the single quantum dot regime.
