Initial theories suggested that isolating two-dimensional (2D) compounds was impossible, as thermal instability would cause the material’s molecular bonds to break apart. The successful isolation of graphene in 2004 disproved these theories and demonstrated the outstanding potential of two-dimensional material manufacturing. However, a quantitative explanation for these unique thermomechanical graphene properties initially proved elusive.
Analysis via transmission electron microscopy (TEM) eventually determined that the nature of graphene’s covalent carbon-carbon (C-C) bonds was responsible for its thermal stability and outstanding strength. These small bonds are also critical in explaining the electronic graphene properties that have resulted in conjecture, hyperbole, and enormous levels of excitement for next generation electronics engineering.
In this blog post, Grolltex will explore these electronic graphene properties in more detail.
Outlining the Electronic Graphene Properties
Graphene has demonstrated extremely high, and near-identical, mobility of both electrons and electron holes at room temperature. This makes it an outstanding charge carrier with reported mobility results exceeding 15,000 cm2·V−1·s−1. Optimistic estimates suggest that graphene’s upper performance limits for charge mobility could range up to 200,000 cm2·V−1·s−1 – although this will depend upon the nature and quality of the substrate. This essentially describes one of the highest performing semimetals ever discovered.
The Underlying Electronic Structure of Graphene Properties
Graphene is defined as a zero-gap semiconductor with extremely high electrical conductivity. These electronic properties are facilitated by the overlapping atomic orbits of adjacent carbon atoms in its 2D sheet.
In an individual carbon atom, two electrons orbit around an inner shell while four are available for chemical bonding in an outer shell. This property changes when multiple carbon atoms are bound together in 2D graphitic sheets. Each atom is bound to three others, freeing up highly-mobile electrons that can occupy a range of energy bands and facilitate electronic conduction. These pi electrons orbit carbon atoms in a third dimension, subsequently overlapping with one another. They enhance the bonding affinity of adjacent atoms and are responsible for the desirable electronic graphene properties.
Dirac points occur where these linear bands meet, creating a linear dispersion spectrum that causes free electrons in the third-dimension to have a zero effective mass. These massless Dirac fermions underly the unique electronic graphene properties, but may require additional dopant electrons or holes to achieve maximum levels of conductivity.
Exploring Graphene Properties with Grolltex
Grolltex is a leading manufacturer of single layer graphene and hBN via chemical vapor deposition (CVD), producing angstrom-scale films on high performance substrate materials. We have developed unique manufacturing techniques to help elevate graphene from an academic curiosity to an industrializable material with outstanding electronic properties.
If you would like more information about our graphene or other 2D materials or heterostructures thereof, or about our manufacturing capabilities, please do not hesitate to contact us directly.