Positioning and numbering Ge quantum dots for effective quantum tunneling devices

The authors have demonstrated a simple method to precisely control the number and the position of nanometer-scaled Ge quantum dots (QDs) embedded in SiO₂ or Si₃N₄ tunnel barriers via thermally oxidizing pre-patterned nanostructures. A single Ge QD in the core or twin Ge QDs near the edges of the nanotrench could be realized by modulating the initial nanostructure´s dimensions and the spacer´s materials. This method offers great promise to realize effective single electron transistors and coupled QD devices for single charge manipulations.