Study on the conductivity of metal-based epitaxial graphene with vacancy defects and anharmonic effects

Abstract

Metal-based epitaxial graphene exhibits extremely high conductivity at room temperature, making the study of its conductance crucial for understanding electron transport mechanisms in two-dimensional materials. In this paper, we applied solid-state physics theories and methods to investigate factors influencing the conductivity of metal-based epitaxial graphene. We considered the variation of conductivity and its temperature stability coefficient with temperature, taking into account the anharmonic vibrations of atoms, and explored the impact of anharmonic effects on conductivity. Using copper-based graphene as an example, we established relationships between temperature and several key parameters: electronic conductivity (σe), conductivity contributed by electron–phonon interactions (σp), conductivity contributed by vacancy defects (σn), and total conductivity (σ), along with its temperature stability coefficient (ασ). All research results were obtained within the temperature range of 300 K to 1200 K. The study reveals that σ decreases nonlinearly as temperature increases, with a magnitude on the order of (Ω ∙ m)-1, which is approximately equal to σp. The conductivity of copper-based epitaxial graphene is found to be greater than that of lithium-based epitaxial graphene. The anharmonic effects of atomic vibrations increase σ, and this increase is more pronounced at higher temperatures. The temperature stability coefficient ασ rapidly decreases with increasing temperature before tending to a constant, indicating that conductivity exhibits better temperature stability at higher temperatures. This paper provides theoretical guidance for understanding electron transport characteristics of metal-based epitaxial graphene and contributes to the design and application of high-performance electronic devices.