Work

Ultrafast terahertz photoconductivity and near-field imaging of nanoscale inhomogeneities in multilayer epitaxial graphene nanoribbons

Year: 2026

Type: article

Abstract: We study broadband terahertz (THz) conductivity and ultrafast photoconductivity spectra in lithographically fabricated multilayer epitaxial graphene nanoribbons grown on C-face of 6H-SiC substrate. THz near-field spectroscopy reveals local conductivity variations across nanoscale structural inhomogeneities such as wrinkles and grain boundaries within the multilayer graphene. Ultrabroadband THz far-field spectroscopy ( 0.15 – 16 THz ) distinguishes doped graphene layers near the substrate from quasineutral layers (QNLs) further from the substrate. Temperature-dependent THz conductivity spectra are dominated by intraband transitions both in the doped and QNLs. Photoexcitation then alters mainly the response of the QNLs: these exhibit very high carrier mobility and large positive THz photoconductivity with picosecond lifetime. The response of QNLs strongly depends on the carrier temperature T c : the scattering time drops by an order of magnitude down to ∼10 fs upon an increase of T c from 50 K to T c > 1000 K , which is attributed to an enhanced electron-electron and electron-phonon scattering and to an interaction of electrons with mid-gap states.

Source: Physical review. B./Physical review. B

DOI: 10.1103/qzns-hs4t

Authors: Arvind Singh, Jan Kunc, Tinkara Troha, Hynek Němec, Petr Kužel

Institutions: FZU - Institute of Physics of the Czech Academy of Sciences, Charles University

Language: English

Topic: Terahertz technology and applications

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Funders: Ministerstvo Školství, Mládeže a Tělovýchovy, Grantová Agentura České Republiky, Central European Institute of Technology

Awards: Research infrastructure CzechNanoLab, Control over terahertz plasmons in graphene nanostructures