Spatially resolved resonant tunneling on single atoms in silicon

TL;DR

This study demonstrates spatially resolved resonant tunneling measurements on single silicon donors near a vacuum interface using STM, providing insights into dopant electrostatics and energy spectra crucial for quantum device development.

Contribution

It introduces a novel experimental approach combining STM with single-electron tunneling to analyze dopants at atomic scale with high spatial and energetic resolution.

Findings

Determined the charging energies of single donors in silicon.

Mapped the energy spectrum and wave-function spatial distribution of dopants.

Highlighted the tunability of vacuum tunnel rates for future quantum experiments.

Abstract

The ability to control single dopants in solid-state devices has opened the way towards reliable quantum computation schemes. In this perspective it is essential to understand the impact of interfaces and electric fields, inherent to address coherent electronic manipulation, on the dopants atomic scale properties. This requires both fine energetic and spatial resolution of the energy spectrum and wave-function, respectively. Here we present an experiment fulfilling both conditions: we perform transport on single donors in silicon close to a vacuum interface using a scanning tunneling microscope (STM) in the single electron tunneling regime. The spatial degrees of freedom of the STM tip provide a versatility allowing a unique understanding of electrostatics. We obtain the absolute energy scale from the thermal broadening of the resonant peaks, allowing to deduce the charging energies of the donors. Finally we use a rate equations model to derive the current in presence of an excited state, highlighting the benefits of the highly tunable vacuum tunnel rates which should be exploited in further experiments. This work provides a general framework to investigate dopant-based systems at the atomic scale.