Graphene: an exotic condensed matter and its impact on technology

Abstract

Graphene is a (2 + 1)-dimensional quantum electrodynamic system. The carriers have a vanishing mass and a relativistic velocity of 106 m/s, obeying charge-conjugate parity time symmetry. Graphene exhibits the Klein paradox, due to which, through spatial confinement, a bandgap can be opened in zigzag graphene nanoribbons for logic applications. The high Debye temperature of 2800 K ensures that phonons are frozen out and lattice scattering is suppressed at 300 K. The perfect crystallinity ensures that defect/impurity scattering is suppressed. The two together give very high electrical conductivity and electric mobility. This permits a current density of 108 A/cm2, about 100 times greater than that in copper. Single-layer graphene has a thermal conductivity of 3000–5000 (W/m)/K at 300 K, but graphite has K = 2000 (W/m)/K. This may open up few-layer graphene applications in thermal management of nanoelectronics. The half-integer quantum Hall effect and non-zero Berry phase have been verified in the laboratory. These magneto-transport properties are a result of the exceptional topology of the graphene band structure. Ballistic transport observable up to 300 K makes graphene an ideal replacement for silicon (Si) electronics. The optical response of graphene is determined by the fine-structure constant over a wide band of the visible spectrum, and hence, it is ideal for high-speed optical modulators. This paper describes a commercially significant process for synthesizing large-area fold-free and defect-free graphene.