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Non-equilibrium band broadening, gap renormalization and band inversion in black phosphorus

Hedayat, H; Ceraso, A; Soavi, G; Akhavan, S; Cadore, A; Dallera, C; Cerullo, G; ... Carpene, E; + view all (2021) Non-equilibrium band broadening, gap renormalization and band inversion in black phosphorus. 2D Materials , 8 (2) , Article 025020. 10.1088/2053-1583/abd89a. Green open access

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Abstract

Black phosphorous (BP) is a layered semiconductor with high carrier mobility, anisotropic optical response and wide bandgap tunability. In view of its application in optoelectronic devices, understanding transient photo-induced effects is crucial. Here, we investigate by time- and angle-resolved photoemission spectroscopy BP in its pristine state and in the presence of Stark splitting, chemically induced by Cs ad-sorption. We show that photo-injected carriers trigger bandgap renormalization, and a concurrent valence band flattening caused by Pauli blocking. In biased samples, photo-excitation leads to a long-lived (ns) surface photovoltage of few hundreds mV that counterbalances the Cs-induced surface band bending. This allows us to disentangle bulk from surface electronic states, and to clarify the mechanism underlying the band inversion observed in bulk samples.

Type: Article
Title: Non-equilibrium band broadening, gap renormalization and band inversion in black phosphorus
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/2053-1583/abd89a
Publisher version: https://doi.org/10.1088/2053-1583/abd89a
Language: English
Additional information: Original Content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: black phosphorus, time-resolved ARPES, Stark effect, surface photovoltage, bandgap renormalization
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office > Institute for Materials Discovery
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office
URI: https://discovery.ucl.ac.uk/id/eprint/10142983
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