Ultraviolet light emission from Si in a scanning tunneling microscope

TL;DR

This study reports ultraviolet and visible light emission from silicon in a scanning tunneling microscope, caused by hot electrons and direct optical transitions, revealing new insights into silicon's luminescence mechanisms.

Contribution

It demonstrates ultraviolet emission from silicon in STM due to hot electrons and identifies the role of direct optical transitions and carrier injection processes.

Findings

Ultraviolet and visible radiation observed from silicon contacts in STM.

Luminescence depends on hot electrons and tunneling processes.

Spectra indicate direct optical transitions in silicon bulk.

Abstract

Ultraviolet and visible radiation is observed from the contacts of a scanning tunneling microscope with Si(100) and (111) wafers. This luminescence relies on the presence of hot electrons in silicon, which are supplied, at positive bias on n- and p-type samples, through the injection from the tip, or, at negative bias on p-samples, by Zener tunneling. Measured spectra reveal a contribution of direct optical transitions in Si bulk. The necessary holes well below the valence band edge are injected from the tip or generated by Auger processes.