Invited contribution by Group Leader Dr Tielrooij in Nanoscale "Emerging Investigators 2021" issue

by Virginia Greco

A review on hot carriers in graphene, authored by ICN2 Junior Group Leader Dr Klaas-Jan Tielrooij, has been published online, as part of a special collection of “Nanoscale” dedicated to works carried out by promising early-career researchers.

The journal Nanoscale of the Royal Society of Chemistry is currently presenting its themed issue Emerging Investigators 2021, aiming at "highlighting 2021’s rising stars of nanoscience and nanotechnology research.” As explained by the publisher, this collection gathers the very best work from researchers in the early stages of their independent career. Contributors were recommended by experts in their fields, due to their potential to influence future directions in nanoscience and nanotechnology with their work.

This issue includes a review article on "Hot Carriers in Graphene – Fundamentals and Applications" authored by Dr Klaas-Jan Tielrooij, leader of the ICN2 Ultrafast Dynamics in Nanoscale Systems group, and colleagues from the University of Sherbrooke, Québec (Canada), Friedrich Schiller University Jena (Germany), and the University of Manchester (UK). The paper offers a summary of the current status of research on hot-carrier effects in graphene and is aimed at a broad audience of scientists, engineers and technologists from both academia and industry, including prospective students.

Hot carriers –which are electrons and holes with excess kinetic energy– in graphene exhibit fascinating physical phenomena and offer great promises for exciting optoelectronic and photonic applications. In particular, hot-carrier-enabled processes that give rise to the emission, conversion, and detection of light can have a disruptive impact, for example in the field of data communication, high-frequency electronics, and industrial quality control.

The review covers first of all the relevant physics of hot carriers in graphene and their working principles. It discusses different techniques for exciting graphene in order to heat the carriers, describes the processes that determine their energy dynamics, and analyses the linear and nonlinear conductivity of hot carriers and their transport properties. Then, an overview of promising applications is provided, focusing on photonic and optoelectronic devices in which hot-carrier effects play a central role, such as photodetectors, nonlinear optical devices and light emitters. Finally, the remarkable properties of hot-carrier phenomena in graphene are compared to those of analogous effects observed in other systems, specifically metals and quantum materials, such as topological insulators.

Reference article:

Mathieu Massicotte, Giancarlo Soavi, Alessandro Principi, and Klaas-Jan Tielrooij, Hot carriers in graphene – fundamentals and applications. Nanoscale, 2021, Advance Article
DOI: 10.1039/D0NR09166A