Fabrication and characterization of Si/SiGe quantum dots with capping gate

Abstract

We study transport properties of quantum point contacts (QPCs) and quantum dots (QDs) with a global capping gate, fabricated on a Si/SiGe high electron mobility transistor (HEMT) wafer. By biasing the capping gate negatively, we succeed in making QPC operation point of surface Schottky gate negatively smaller and then reducing noise. We also observe Coulomb oscillations using a QD structure by suppressing charging noise with negative capping gate voltage.