  We report on the fabrication and characterization of quantum dot devices in a
Schottky-gated silicon/silicon-germanium two-dimensional electron gas (2DEG).
The dots are confined laterally inside an etch-defined channel, while their
potential is modulated by an etch-defined 2DEG gate in the plane of the dot.
For the first time in this material, Schottky top gates are used to define and
tune the tunnel barriers of the dot. The leakage current from the gates is
reduced by minimizing their active area. Further suppression of the leakage is
achieved by increasing the etch depth of the channel. The top gates are used to
put the dot into the Coulomb blockade regime, and conductance oscillations are
observed as the voltage on the side gate is varied.
