Single-Electron Transistor in Strained Si/SiGe Heterostructures
  A split gate technique is used to form a lateral quantum dot in a two-dimensional electron gas of a modulation-doped silicon/silicon-germanium heterostructure. e-beam lithography was employed to produce split gates. By applying negative voltages to these gates the underlying electron gas is depleted and a lateral quantum dot is formed, the size of which can be adjusted by the gate voltage. We observe single-electron operation with Coulomb blockade behavior below 1K. Gate leakage currents are well controlled, indicating that the recently encountered problems with Schottky gates for this type of application are not an inherent limitation of modulation-doped Si/SiGe heterostructures, as had been speculated. 
Thomas Berer, Dietmar Pachinger, Georg Pillwein, Michael Muehlberger,   Herbert Lichtenberger, Gerhard Brunthaler, and F. Sc...