Mechanism of electron-beam manipulation of single dopant atoms in silicon

TL;DR

This paper uncovers a new indirect exchange mechanism enabling atomic-precision manipulation of heavy group V dopants in silicon using electron beams, advancing quantum device fabrication.

Contribution

It introduces a novel indirect exchange mechanism for electron-beam manipulation of dopants and verifies it through imaging and manipulation experiments.

Findings

The mechanism works for Bi and Sb dopants with split-vacancy configurations.

Direct imaging confirms the predicted dopant configurations.

Focused electron beams can manipulate Sb nuclear spin qubits.

Abstract

The precise positioning of dopant atoms within bulk crystal lattices could enable novel applications in areas including solid-state sensing and quantum computation. Established scanning probe techniques are capable tools for the manipulation of surface atoms, but at a disadvantage due to their need to bring a physical tip into contact with the sample. This has prompted interest in electron-beam techniques, followed by the first proof-of-principle experiment of bismuth dopant manipulation in crystalline silicon. Here, we use first principles modeling to discover a novel indirect exchange mechanism that allows electron impacts to non-destructively move dopants with atomic precision within the silicon lattice. However, this mechanism only works for the two heaviest group V donors with split-vacancy configurations, Bi and Sb. We verify our model by directly imaging these configurations for Bi, and by demonstrating that the promising nuclear spin qubit Sb can be manipulated using a focused electron beam.