Direct momentum-resolved observation of one-dimensional confinement of externally doped electrons within a single subnanometre-scale wire

TL;DR

This study demonstrates the direct measurement of one-dimensional electron confinement within a single subnanometre-scale wire using ARPES, revealing how external doping influences electron localization at the atomic scale.

Contribution

It provides the first direct ARPES evidence of 1D electron confinement in a single nanowire and shows controlled doping effects without disrupting the wire structure.

Findings

Confirmed 1D electron confinement in gold subnanowires

Demonstrated selective doping control of individual nanowires

Analyzed disorder effects induced by external dopants

Abstract

Cutting-edge research in the band engineering of nanowires at the ultimate fine scale is related to the minimum scale of a nanowire-based device. The fundamental issue at the subnanometre scale is whether angle-resolved photoemission spectroscopy (ARPES) can be used to directly measure the momentum-resolved electronic structure of a single wire because of the difficulty associated with assembling single wire into an ordered array for such measurements. Here, we demonstrated that the one-dimensional (1D) confinement of electrons, which are transferred from external dopants, within a single subnanometre-scale wire (subnanowire) could be directly measured using ARPES. Convincing evidence of 1D electron confinement was obtained using two different gold subnanowires with characteristic single metallic bands that were alternately and spontaneously ordered on a stepped silicon template, Si(553). Noble metal atoms were adsorbed at room temperature onto the gold subnanowires while maintaining the overall structure of the wires. Only one type of gold subnanowires could be controlled using external noble metal dopants without transforming the metallic band of the other type of gold subnanowires. This result was confirmed by scanning tunnelling microscopy experiments and first-principles calculations. The selective control clearly showed that externally doped electrons could be confined within a single gold subnanowire. This experimental evidence was used to further investigate the effects of the disorder induced by external dopants on a single subnanowire using ARPES.