Single Electron Dynamics of an Atomic Silicon Quantum Dot on the H-Si(100) 2x1 Surface

TL;DR

This study directly observes and analyzes the single electron charging dynamics of a single atomic dangling bond on a silicon surface using scanning tunneling microscopy, revealing detailed charge state behavior and tunneling characteristics.

Contribution

It provides the first direct measurement of single electron charging states and dynamics of an atomic silicon dangling bond on H-Si(100) surface, using STM as a charge detector.

Findings

Identified three charge states: positive, neutral, negative.

Charge filling rates decay exponentially with tip-DB distance.

Emptying rates depend strongly on sample bias, weakly on tip position.

Abstract

Here we report the direct observation of single electron charging of a single atomic Dangling Bond (DB) on the H-Si(100) 2x1 surface. The tip of a scanning tunneling microscope is placed adjacent to the DB to serve as a single electron sensitive charge-detector. Three distinct charge states of the dangling bond, positive, neutral, and negative, are discerned. Charge state probabilities are extracted from the data, and analysis of current traces reveals the characteristic single electron charging dynamics. Filling rates are found to decay exponentially with increasing tip-DB separation, but are not a function of sample bias, while emptying rates show a very weak dependence on tip position, but a strong dependence on sample bias, consistent with the notion of an atomic quantum dot tunnel coupled to the tip on one side and the bulk silicon on the other.