CNR ExploRA

Articolo in rivista, 2021, ENG, 10.1021/acs.jpcc.1c03531

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

Abhishek Kumar, Francesca Telesio, Deborah Prezzi, Claudia Cardoso, Alessandra Catellani, Stiven Forti, Camilla Coletti, Manuel Serrano-Ruiz, Maurizio Peruzzini, Fabio Beltram, and Stefan Heun

NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy; S3, Istituto Nanoscienze-CNR, Via Campi 213/A, 41125 Modena, Italy; Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa, Italy; CNR-ICCOM, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy;

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.

Journal of physical chemistry. C. (Online) 125 (24), pp. 13477–13484