Abstract. We report on the fabrication and characterization of quantum-dot devices in a Schottky-gated silicon/silicon–germanium modulation-doped 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.

Received 3 August 2005
Published 29 November 2005