Accessing the spectral function of in operando devices by angle-resolved photoemission spectroscopy

TL;DR

This paper reviews recent advances in nanoARPES technology enabling in operando measurements of electronic structures in tiny devices, revealing local electronic properties and interactions under real operating conditions.

Contribution

It introduces the application of nanoARPES to in operando device studies, providing new insights into local electronic behavior and future prospects for the technique.

Findings

NanoARPES can detect changes in electronic structure during device operation.

It maps local doping, conductance, and mobility in real-time.

The technique offers detailed insights into many-body interactions in devices.

Abstract

Progress in performing angle-resolved photoemission spectroscopy (ARPES) with high spatial resolution in the order of 1~$\mu$m or less (nanoARPES) has opened the possibility to map the spectral function of solids on this tiny scale and thereby obtain detailed information on the materials' \emph{local} electronic band structure and many-body interactions. Recently, nanoARPES has been used to study simple electronic devices, based on two-dimensional materials, with the possibility of tuning the carrier type and density by field effect-gating, and while passing a current through the device. It was demonstrated that nanoARPES can detect possible changes in the materials' electronic structure in these situations and that it can map the local doping, conductance and mobility. This article reviews these first \emph{in operando} ARPES results on devices, discusses the resulting new insights, as well as the perspectives for future developments of the technique.