Transport in graphene nanostructures

Abstract

Graphene nanostructures are promising candidates for future nanoelectronics and solid-state quantum information technology. In this review we provide an overview of a number of electron transport experiments on etched graphene nanostructures. We briefly revisit the electronic properties and the transport characteristics of bulk, i.e., two-dimensional graphene. The fabrication techniques for making graphene nanostructures such as nanoribbons, single electron transistors and quantum dots, mainly based on a dry etching "paper-cutting" technique are discussed in detail. The limitations of the current fabrication technology are discussed when we outline the quantum transport properties of the nanostructured devices. In particular we focus here on transport through graphene nanoribbons and constrictions, single electron transistors as well as on graphene quantum dots including double quantum dots. These quasi-one-dimensional (nanoribbons) and quasi-zero-dimensional (quantum dots) graphene nanostructures show a clear route of how to overcome the gapless nature of graphene allowing the confinement of individual carriers and their control by lateral graphene gates and charge detectors. In particular, we emphasize that graphene quantum dots and double quantum dots are very promising systems for spin-based solid state quantum computation, since they are believed to have exceptionally long spin coherence times due to weak spin-orbit coupling and weak hyperfine interaction in graphene.

Single-electron transport in graphene-like nanostructures

“…Engineering band gaps in graphene is thus a major challenge that must be addressed to enable the use of graphenebased transistors in digital electronics. First-principle calculations predict that cutting graphene into one-dimensional nanoribbons can open up a scalable band gap E g = α/w, where w is the nanoribbon width and α is in the range of 0.2 eV·nm to 1.5 eV·nm, depending on the model and the crystallographic orientation of the edges [10,65]. Similar results are also obtained from tight-binding calculations [66,67].…”

“…Additional relevant reviews of research on GQDs on SiO 2 substrates can be found in ref. [10][11][12][13]. We conclude the main observations with the summary of references given in Table I.…”

“…Graphene is a robust material for spintronics owing to its weak spin-orbit and hyperfine interactions. Over the last decade, attempts to confine and manipulate single charges in graphene quantum dots (GQDs) have been widely studied and reported, as noted in several review articles [10][11][12][13]. However, early studies of GQDs on SiO 2 have indicated an absence of spin-related phenomena, such as spin blockade and the Kondo effect.…”

Roles of Mass, Structure, and Bond Strength in the Phonon Properties and Lattice Anharmonicity of Single-Layer Mo and W Dichalcogenides

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Mo and W dichalcogenides (MX 2 , M = Mo, W; X = S, Se, Te) are two important similar families of two-dimensional materials, which have been widely prepared and characterized in experiment. 2,8,12,[17][18][19] MX 2 has a band gap of 1.0-2.1 eV, 4,9,10,14,20 therefore, the fieldeffect transistors made from single-layer (SL) MX 2 have a high on/off ratio (10 3 -10 8 ).…”

Electronic and quantum transport properties of a graphene-BN dot-ring hetero-nanostructure

“…Ever since the experimental discovery of graphene [1] an immense body of theoretical and experimental work has accumulated [2] that explores the unusual conduction and transport properties (for a review see for example [3]) and possible applications in nanoelectronics and nanooptical devices. Electronic, magnetic, and optical properties of graphene quantum dots (QD) [4,5], graphene nanoribbons [6,7], and graphene quantum rings (QR) [8] have been analyzed.…”