We study surface charge transfer doping of exfoliated black phosphorus (bP) flakes by copper using scanning tunneling microscopy (STM) and spectroscopy (STS) at room temperature. The tunneling spectra reveal a gap in correspondence of Cu islands, which is tentatively attributed to Coulomb blockade phenomena. Moreover, using line spectroscopic measurements across small copper islands, we exploit the potential of the local investigation, showing that the n-type doping effect of copper on bP is short-ranged. These experimental results are substantiated by first-principles simulations, which quantify the role of cluster size for an effective n-type doping of bP and show an electronic decoupling of the topmost bP layer from the underlying layers driven by the copper cluster, consistent with the Coulomb blockade interpretation. Our results provide novel understanding—difficult to retrieve by transport measurements—of the doping of bP by copper, which appears promising for the implementation of ultrasharp p-n junctions in bP.

Black Phosphorus n-Type Doping by Cu: A Microscopic Surface Investigation

Kumar, Abhishek;Prezzi, Deborah
;
Coletti, Camilla;Beltram, Fabio;
2021

Abstract

We study surface charge transfer doping of exfoliated black phosphorus (bP) flakes by copper using scanning tunneling microscopy (STM) and spectroscopy (STS) at room temperature. The tunneling spectra reveal a gap in correspondence of Cu islands, which is tentatively attributed to Coulomb blockade phenomena. Moreover, using line spectroscopic measurements across small copper islands, we exploit the potential of the local investigation, showing that the n-type doping effect of copper on bP is short-ranged. These experimental results are substantiated by first-principles simulations, which quantify the role of cluster size for an effective n-type doping of bP and show an electronic decoupling of the topmost bP layer from the underlying layers driven by the copper cluster, consistent with the Coulomb blockade interpretation. Our results provide novel understanding—difficult to retrieve by transport measurements—of the doping of bP by copper, which appears promising for the implementation of ultrasharp p-n junctions in bP.
2021
Settore FIS/03 - Fisica della Materia
   Phosphorene functionalization: a new platform for advanced multifunctional materials
   PHOSFUN
   European Commission
   Horizon 2020 Framework Programme
   670173
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/137147
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