Conductance oscillations in Ge/Si heterostructures containing quantum dots

The conductance of the Si/p+-Ge/Si epitaxial heterostructure associated with hole tunnelling into isolated ultrasmall ( approximately 10 nm) quantum dots p+-Ge has been studied. Quantum dots have been obtained after islanding of 1.3 nm Ge film during MBE growth by the Stransky-Krastanov mode method. Conductance oscillations as a function of bias voltage were observed. The experimental data are analysed in terms of a model that involves the interplay of single-electron charging effects and resonant tunnelling through individual energy levels.