PtSe2 is a van der Waals material transitioning from an indirect bandgap semiconductor to a semimetal with increasing thickness. Its absorption threshold has been conjectured to originate from interband indirect transitions. By quantitative comparison between broadband (0.8−3.0eV) optical absorption of high-quality exfoliated crystals and DFT ab-initio simulations, we prove instead that the optical absorption arises only from direct transitions. This understanding allows us to shed light on the semiconductor to semimetal transition and to explore the effect of stacking and excitons on the optical absorption.
@article{arxiv.2311.01847,
title = {The optical absorption in indirect semiconductor to semimetal PtSe2 arises from direct transitions},
author = {Marin Tharrault and Sabrine Ayari and Mehdi Arfaoui and Eva Desgué and Romaric Le Goff and Pascal Morfin and José Palomo and Michael Rosticher and Sihem Jaziri and Bernard Plaçais and Pierre Legagneux and Francesca Carosella and Christophe Voisin and Robson Ferreira and Emmanuel Baudin},
journal= {arXiv preprint arXiv:2311.01847},
year = {2025}
}