Kremer, Geoffroy Rumo, Maxime Yue, Changming Pulkkinen, Aki Nicholson, Christopher W. Jaouen, Thomas Rohr, Fabian O. von Werner, Philipp Monney, Claude 2021 Black phosphorus is a quasi-two-dimensional layered semiconductor with a narrow direct band gap of 0.3 eV. A giant surface Stark effect can be produced by the potassium doping of black phosphorus, leading to a semiconductor to semimetal phase transition originating from the creation of a strong surface dipole and associated band bending. By using time- and angle-resolved photoemission spectroscopy, we report the partial photoinduced screening of this band bending by the creation of a compensating surface photovoltage. We further resolve the detailed dynamics of this effect at the pertinent timescales and the related evolution of the band structure near the Fermi level. We demonstrate that after a fast rise time, the surface photovoltage exhibits a plateau over a few tens of picoseconds before decaying on the nanosecond timescale. We support our experimental results with simulations based on drift-diffusion equations. application/pdf https://folia.unifr.ch/global/documents/309574 https://folia.unifr.ch/documents/309574/files/kremer_et_al_2021_ultrafast.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.104.035125 info:eu-repo/semantics/openAccess License undefined Physical Review B. - 2021, vol. 104, no. 3, p. 035125 Electronic structure Ultrafast phenomena 2-dimensional systems Semiconductors Time and angle resolved photoemission spectroscopy info:eu-repo/classification/udc/53 Ultrafast dynamics of the surface photovoltage in potassium-doped black phosphorus http://purl.org/coar/resource_type/c_6501