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

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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• Investigation of the Non-equilibrium State of Strongly Correlated Materials by Complementary Ultrafast Spectroscopy Techniques
• Long-Term Environmental Stability of Nitrogen-Healed Black Phosphorus
• Ultrafast Dynamics of the Surface Photovoltage in Potassium Doped Black Phosphorus
• Ultrafast Evolution of Bulk, Surface and Surface Resonance States in Photoexcited Bi${}_2$Te${}_3$
• Site-specific symmetry sensitivity of angle-resolved photoemission spectroscopy in layered palladium diselenide
• Quantum well confinement and competitive radiative pathways in the luminescence of black phosphorus layers
• Cross-Examination of Photoinitiated Carrier and Structural Dynamics of Black Phosphorus at Elevated Fluences
• Low-frequency interlayer phonon dynamics and photoinduced terahertz absorption in black phosphorus
• Non-adiabatic suppression of 3D excitonic screening in black phosphorus by mid-infrared pulses