  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.
