Quantum dots with split enhancement gate tunnel barrier control

TL;DR

This paper presents a novel silicon quantum dot architecture with split enhancement gates that allows wide tunability of tunnel rates while maintaining single-electron occupation, improving control and potential scalability.

Contribution

The authors introduce a new all-silicon quantum dot design with split gates, demonstrating broad tunnel rate control and reduced noise, advancing quantum dot fabrication and operation techniques.

Findings

Wide range of tunnel rates achieved in three devices

Characteristic slope change in charge transitions observed

All-silicon process reduces strain and noise issues

Abstract

We introduce a silicon metal-oxide-semiconductor quantum dot architecture based on a single polysilicon gate stack. The elementary structure consists of two enhancement gates separated spatially by a gap, one gate forming a reservoir and the other a quantum dot. We demonstrate, in three devices based on two different versions of this elementary structure, that a wide range of tunnel rates is attainable while maintaining single-electron occupation. A characteristic change in slope of the charge transitions as a function of the reservoir gate voltage, attributed to screening from charges in the reservoir, is observed in all devices, and is expected to play a role in the sizable tuning orthogonality of the split enhancement gate structure. The all-silicon process is expected to minimize strain gradients from electrode thermal mismatch, while the single gate layer should avoid issues related to overlayers (e.g., additional dielectric charge noise) and help improve yield. Finally, reservoir gate control of the tunnel barrier has implications for initialization, manipulation and readout schemes in multi-quantum dot architectures.