Room-Temperature Charge Stability Modulated by Quantum Effects in a Nanoscale Silicon Island

TL;DR

This study demonstrates that quantum effects in a sub-5nm silicon island enable stable charge states at room temperature, with complex Coulomb diamond features explained by quantum interactions.

Contribution

It introduces a model that explains room-temperature charge stability in ultra-small silicon islands by incorporating Coulomb interaction, valley splitting, and quantum confinement effects.

Findings

Charge stability persists at 300K despite Coulomb diamond changes.

Quantum confinement leads to low-energy many-body excited states.

Charge stability features are modeled successfully with quantum effects.

Abstract

We report on transport measurement performed on a room-temperature-operating ultra-small Coulomb blockade devices with a silicon island of sub-5nm. The charge stability at 300K exhibits a substantial change in slopes and diagonal size of each successive Coulomb diamond, but remarkably its main feature persists even at low temperature down to 5.3K except for additional Coulomb peak splitting. This key feature of charge stability with additional fine structures of Coulomb peaks are successfully modeled by including the interplay between Coulomb interaction, valley splitting, and strong quantum confinement, which leads to several low-energy many-body excited states for each dot occupancy. These excited states become enhanced in the sub-5nm ultra-small scale and persist even at 300K in the form of cluster, leading to the substantial modulation of charge stability.