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arXiv · 2007.09754

Non-equilibrium Band Broadening, Gap Renormalization and Band Inversion in Black Phosphorus

H. Hedayat·A. Ceraso·G. Soavi·S. Akhavan·A. Cadore·C. Dallera·G. Cerullo·A. C. Ferrari·E. Carpene
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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 attening caused by Pauli blocking. In the biased sample, photoexcitation 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.

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H. Hedayat, A. Ceraso, G. Soavi, S. Akhavan, A. Cadore, C. Dallera, G. Cerullo, A. C. Ferrari, E. Carpene. 2020-07-19. Non-equilibrium Band Broadening, Gap Renormalization and Band Inversion in Black Phosphorus. https://doi.org/10.1088/2053-1583%2Fabd89a

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