Precise Ge quantum dot placement for quantum tunneling devices

This study demonstrates the precise placement of Ge quantum dots (QDs) in an SiO₂ or Si₃N₄ matrix in a self-organized manner by thermally oxidizing SiGe in nanostructures. The effectiveness of this method is shown by a variety of geometries including nanotrenches, nanorods and polygonal nanocavities. Modulating the structural geometry and peripheral spacer materials effectively places a single Ge QD in the center of an oxidized SiGe nanostructure or individual QDs at the corners (edges). This study also reports the fabrication of Ge QD single-electron devices that exhibit clear Coulomb staircases and differential conductance oscillations at room temperature.