Si/SiGe quantum dot with superconducting single-electron transistor charge sensor

Abstract

We report a robust process for fabrication of surface-gated Si/SiGe quantum dots (QDs) with an integrated superconducting single-electron transistor (SSET) charge sensor. A combination of a deep mesa etch and AlOx backfill is used to reduce gate leakage. After the leakage current is suppressed, Coulomb oscillations of the QD and the current-voltage characteristics of the SSET are observed at a temperature of 0.3 K. Coupling of the SSET to the QD is confirmed by using the SSET to perform sensing of the QD charge state.