Graphene: The Single-Atom-Thick Carbon Sheet With No Bandgap

Graphene is a single layer of carbon atoms bonded in a hexagonal honeycomb lattice (sp2 bonds, ~0.142 nm bond length), the basic building block of graphite. It was isolated and characterized in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester using mechanical exfoliation (the "Scotch tape" method), work that earned the 2010 Nobel Prize in Physics. Graphene's electronic properties are exceptional: room-temperature carrier mobility exceeding 15,000 cm2/V/s (far higher in suspended samples), resistivity around 1e-8 ohm-m (lower than silver), thermal conductivity near 5,000 W/m/K, tensile strength around 130 GPa, and Young's modulus close to 1 TPa, all while absorbing only ~2.3% of visible light per layer. The catch for digital electronics is that graphene is a zero-gap semimetal: its conduction and valence bands touch at the Dirac points, so it has no bandgap. A transistor needs a bandgap to turn fully off; without one, current keeps flowing at zero gate voltage, ruining the on/off ratio that logic requires. This is why graphene, despite its speed, is not a drop-in replacement for silicon in CPUs, and why materials like Transition Metal Dichalcogenides (TMDs): Atomically Thin 2D Semiconductors, which do have a bandgap, are studied for logic instead. Graphene's near-term promise lies in high-frequency analog/RF devices, transparent and flexible electronics, photonics, sensors, and composites. Black Semiconductor's FabONE in Aachen, Germany, is building one of the first 300 mm fabs for graphene-based photonic chip technology, with an operational pilot line targeted for 2026 and volume production around 2029. See No Single Successor to Silicon: The Heterogeneous Future of Chip Materials for context.