Nearly Massless Electrons in the Silicon Interface with a Metal Film

TL;DR

This paper reports the discovery of nearly massless electrons at the silicon-metal interface, achieved through angle-resolved photoemission, revealing potential for advanced silicon-based thin-film electronic devices.

Contribution

It demonstrates the existence of nearly massless electrons in silicon at a metal interface, a novel finding enabled by angle-resolved photoemission spectroscopy.

Findings

Surface band of lead film induces nearly linear dispersion in silicon

Effective mass of electrons is about 20 times lighter than bulk silicon

Interaction between metal film bands and silicon substrate explains mass reduction

Abstract

We demonstrate the realization of nearly massless electrons in the most widely used device material, silicon, at the interface with a metal film. Using angle-resolved photoemission, we found that the surface band of a monolayer lead film drives a hole band of the Si inversion layer formed at the interface with the film to have nearly linear dispersion with an effective mass about 20 times lighter than bulk Si and comparable to graphene. The reduction of mass can be accounted for by repulsive interaction between neighboring bands of the metal film and Si substrate. Our result suggests a promising way to take advantage of massless carriers in silicon-based thin-film devices, which can also be applied for various other semiconductor devices.