Time-Resolved Single Dopant Charge Dynamics in Silicon

TL;DR

This study employs advanced time-resolved scanning tunnelling microscopy to observe and quantify the charge dynamics of individual dopants in silicon at nanosecond timescales, revealing ionization and neutralization processes.

Contribution

It introduces a novel application of atomically resolved pump-probe STM to measure single dopant charge dynamics with unprecedented temporal resolution.

Findings

Distinct ionization and neutralization rates measured

Physical processes controlling dopant charge states identified

Quantitative analysis of single dopant dynamics achieved

Abstract

As the ultimate miniaturization of semiconductor devices approaches, it is imperative that the effects of single dopants be clarified. Beyond providing insight into functions and limitations of conventional devices, such information enables identification of new device concepts. Investigating single dopants requires sub-nanometre spatial resolution, making scanning tunnelling microscopy an ideal tool. However, dopant dynamics involve processes occurring at nanosecond timescales, posing a significant challenge to experiment. Here we use time-resolved scanning tunnelling microscopy and spectroscopy to probe and study transport through a dangling bond on silicon before the system relaxes or adjusts to accommodate an applied electric field. Atomically resolved, electronic pump-probe scanning tunnelling microscopy permits unprecedented, quantitative measurement of time-resolved single dopant ionization dynamics. Tunnelling through the surface dangling bond makes measurement of a signal that would otherwise be too weak to detect feasible. Distinct ionization and neutralization rates of a single dopant are measured and the physical process controlling those are identified.