Single-hole tunnelling in SiGe nanostructures

We have fabricated quantum dots and quantum wires in p-type silicon germanium grown on SOI substrates. Electrical characteristics at low temperature show clear Coulomb blockade and Coulomb staircases in both structures. Gate-controlled experiments show conductance oscillations with a single period in quantum dots and multiple periods in quantum wires. While single-hole tunnelling is easily achieved in quantum dots, a more complicated hole transport results in quantum wires with a narrow control range for a true single-hole tunnelling.