The interaction between an electric field and the electric charges in a material is described by electrostatic screening, which in metallic systems is commonly thought to be confined within a distance of the order of the Thomas–Fermi length. The validity of this picture, which holds for surface charges up to ~ 10^13 cm^(−2), has been recently questioned by several experimental results when dealing with larger surface charges, such as those routinely achieved via the ionic gating technique. Whether these results can be accounted for in a purely electrostatic picture is still debated. In this work, we tackle this issue by calculating the spatial dependence of the charge carrier density in thin slabs of niobium nitride via an ab initio density functional theory approach in the field-effect transistor configuration. We find that perturbations induced by surface charges < 10^14 cm^(−2) are mainly screened within the first layer, while those induced by larger surface charges ~ 10^15 cm^(−2) can penetrate over multiple atomic layers, in reasonable agreement with the available experimental data. Furthermore, we show that a significant contribution to the screening of large fields is associated not only to the accumulation layer of the induced charge carriers at the surface, but also to the polarization of the pre-existing charge density of the undoped system.

Anomalous screening of an electrostatic field at the surface of niobium nitride / Piatti, Erik; Romanin, Davide; Gonnelli, Renato; Daghero, Dario. - In: APPLIED SURFACE SCIENCE. - ISSN 0169-4332. - STAMPA. - 461:(2018), p. 17. [10.1016/j.apsusc.2018.05.181]

Anomalous screening of an electrostatic field at the surface of niobium nitride

Erik Piatti;Davide Romanin;Renato Gonnelli;Dario Daghero
2018

Abstract

The interaction between an electric field and the electric charges in a material is described by electrostatic screening, which in metallic systems is commonly thought to be confined within a distance of the order of the Thomas–Fermi length. The validity of this picture, which holds for surface charges up to ~ 10^13 cm^(−2), has been recently questioned by several experimental results when dealing with larger surface charges, such as those routinely achieved via the ionic gating technique. Whether these results can be accounted for in a purely electrostatic picture is still debated. In this work, we tackle this issue by calculating the spatial dependence of the charge carrier density in thin slabs of niobium nitride via an ab initio density functional theory approach in the field-effect transistor configuration. We find that perturbations induced by surface charges < 10^14 cm^(−2) are mainly screened within the first layer, while those induced by larger surface charges ~ 10^15 cm^(−2) can penetrate over multiple atomic layers, in reasonable agreement with the available experimental data. Furthermore, we show that a significant contribution to the screening of large fields is associated not only to the accumulation layer of the induced charge carriers at the surface, but also to the polarization of the pre-existing charge density of the undoped system.
File in questo prodotto:
File Dimensione Formato  
SURFINT2017_Daghero_preprint_final.pdf

embargo fino al 24/05/2020

Descrizione: Articolo principale
Tipologia: 2. Post-print / Author's Accepted Manuscript
Licenza: Creative commons
Dimensione 3.86 MB
Formato Adobe PDF
3.86 MB Adobe PDF Visualizza/Apri
Piatti Anomalous screening of an electrostatic field at the surface of niobium nitride Appl. Surf. Sci. 461, 17 (2018).pdf

non disponibili

Descrizione: Articolo principale - versione editoriale
Tipologia: 2a Post-print versione editoriale / Version of Record
Licenza: Non Pubblico - Accesso privato/ristretto
Dimensione 1.11 MB
Formato Adobe PDF
1.11 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11583/2715847
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo