Remote capacitive sensing in two-dimension quantum-dot arrays

TL;DR

This paper explores capacitive sensing in silicon-based quantum-dot arrays, demonstrating enhanced charge detection capabilities through floating gates and analyzing inter-dot coupling in nanowire structures.

Contribution

It introduces a method for capacitive sensing in 2D quantum-dot arrays using floating gates to improve charge sensitivity and extends understanding of inter-dot coupling in silicon nanowire systems.

Findings

Floating gates enhance charge sensitivity range.

Inter-dot capacitive coupling can be extended across nanowires.

Charge sensitivity decreases with increased dot-sensor separation.

Abstract

We investigate gate-defined quantum dots in silicon on insulator nanowire field-effect transistors fabricated using a foundry-compatible fully-depleted silicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the silicon nanowire naturally produces a $2\times n$ bilinear array of quantum dots along a single nanowire. We begin by studying the capacitive coupling of quantum dots within such a 2$\times$2 array, and then show how such couplings can be extended across two parallel silicon nanowires coupled together by shared, electrically isolated, 'floating' electrodes. With one quantum dot operating as a single-electron-box sensor, the floating gate serves to enhance the charge sensitivity range, enabling it to detect charge state transitions in a separate silicon nanowire. By comparing measurements from multiple devices we illustrate the impact of the floating gate by quantifying both the charge sensitivity decay as a function of dot-sensor separation and configuration within the dual-nanowire structure.