Low-energy electron inelastic mean free path for monolayer graphene

• Published in: Applied physics letters Vol. 117; no. 3
• Main Authors: Nguyen-Truong, Hieu T., Da, Bo, Yang, Lihao, Ding, Zejun, Yoshikawa, Hideki, Tanuma, Shigeo
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 20-07-2020
• Subjects: Applied physics; Density functional theory; Graphene; Mean free path; Monolayers; Monte Carlo simulation; Spectrum analysis; Substrates; Time dependence; Two dimensional materials
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0016284

The electron inelastic mean free path (IMFP) is an important quantity for electron spectroscopy and microscopy techniques. At present, there are very few data of IMFPs for two-dimensional (2D) materials. Here, we determine the IMFP at energies below 100 eV for monolayer graphene both experimentally and theoretically. The experimental determination is based on a data-driven spectral analysis technique, including the virtual substrate method and the reverse Monte Carlo method. The theoretical determination is performed within the dielectric formalism, using the energy-loss function calculated in the time-dependent density functional theory. The experimental and theoretical results show that the IMFP for monolayer graphene is almost constant (about 1 nm) in the energy range of 6–100 eV. This study suggests a general and reliable approach to determine low-energy IMFPs for 2D materials.