1. Non-equilibrium band broadening, gap renormalization and band inversion in black phosphorus
- Author
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Andrea C. Ferrari, Claudia Dallera, Ettore Carpene, H. Hedayat, A. Ceraso, Giancarlo Soavi, Alisson R. Cadore, Shahab Akhavan, Giulio Cerullo, Ferrari, Andrea [0000-0003-0907-9993], Apollo - University of Cambridge Repository, Ferrari, A C [0000-0003-0907-9993], and Carpene, E [0000-0003-3867-8178]
- Subjects
Paper ,Electron mobility ,Materials science ,balck phosphorus ,Band gap ,Photoemission spectroscopy ,Stark effect ,Surface photovoltage ,FOS: Physical sciences ,02 engineering and technology ,time-resolved ,black phosphorus ,01 natural sciences ,symbols.namesake ,Pauli exclusion principle ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,General Materials Science ,010306 general physics ,bandgap renormalization ,Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,business.industry ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,General Chemistry ,surface photovoltage ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Photoexcitation ,Semiconductor ,Mechanics of Materials ,time-resolved ARPES ,symbols ,0210 nano-technology ,business ,photoemission - Abstract
Funder: ERC Grants Hetero2D, Funder: GSYNCOR, Funder: EU Graphene Flagship, 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.
- Published
- 2021