Theory and synthesis of bilayer graphene intercalated with ICl and IBr for low power device applications

Abstract

Graphene intercalation materials are potentially promising for the implementation of the ultra-low power, excitonic-condensate-based Bilayer pseudoSpin Field-Effect Transistor (BiS-FETs) concept, as well as other novel device concepts requiring a graphene interlayer dielectric. Using density functional theory (DFT) we study the structural and electronic properties of bilayer graphene intercalated with iodine monochloride (ICl) and iodine monobromide (IBr).We determine the structural configuration of ICl and IBr graphene intercalation compounds (GICs). We also conduct an in-depth exploration of inter-layer electronic coupling, using ab initio calculations. The presence of intercalants dopes the graphene layer. It also reduces, but does not eliminate, the electronic coupling between graphene layers, which may enable BiSFET operation. In addition, we present experimental results for ICl-GIC synthesis and characterization.

Properties and applications of chemically functionalized graphene

“…The experimental realization of intercalation of molecular and atomic species into quasi-free FLG was recently reported for K, Rb [195], ICl and IBr [196] using the vapour-phase method. In particular, partial intercalation of K and Rb was performed by means of a two-zone vapour-phase method at 210 and 160 • C, whereas the intercalation of ICl and IBr requires relatively low temperatures (just 35 • C).…”

“…A large upshift of the G-peak in the Raman spectra is commonly observed upon intercalation, and it signifies that a large charge transfer occurs from (to) the molecular or atomic specie to (from) graphene. Furthermore, a strong anisotropy of resistance manifested in high c-axis (perpendicular to graphene planes) resistivity is expected [196] owing to a strong localization of the π -electronic orbitals in the graphene layers separated by ICl or IBr. The substantial reduction of the coupling between intercalated graphene layers makes these systems promising for studying excitonic condensates.…”

Chainlike Structure Formed in Iodine Monochloride Graphite Intercalation Compounds

“…Polar heteroatomic halogen GICs such as iodine monochloride (ICl), although barely studied, have been known since the 1950s, and offer access to GICs at room temperature overcoming the above-mentioned difficulties. [35][36][37][38][39][40][41][42][43] The stoichiometry of a stage-1 ICl GIC intercalation compound, i.e. consisting of alternating single layers of carbon and intercalant, has been suggested to be close to 10:1 in analogy with other acceptor intercalation compounds (e.g FeCl 3 ).…”

“…Polar heteroatomic halogen GICs such as iodine monochloride (ICl), although barely studied, have been known since the 1950s and offer access to GICs at room temperature, overcoming the abovementioned difficulties. − The stoichiometry of a stage 1 ICl-GIC intercalation compound, i.e., consisting of alternating single layers of carbon and intercalant, has been suggested to be close to 10:1 in analogy with other acceptor intercalation compounds (e.g., FeCl 3 ). , Early structural analysis by Abe et al reported an interlayer spacing of 7.14 Å. Moret et al performed a detailed crystallographic analysis and suggested that the stage 1 GIC exhibits an incommensurate structure with a large unit cell, proposing up to nine ICl molecules in the unit cell . Later, extended X-ray absorption spectroscopy and near-edge X-ray absorption fine structure analysis (EXAFS) showed characteristic distances assigned to I–Cl and halogen-carbon bonds .…”

Antiferromagnetic ordering and excitonic pairing in the AA-stacked bilayer graphene

“…The electronic properties of the AB-stacked and AAstacked bilayer graphene (BLG) structures, their optical characteristics and excitonic phases have been the subject of many experimental and theoretical works . Beside the fact that the AB-BLG is very promising for technological applications, the AA-BLG shows intriguing properties when exposed to the external electric field [1, 2, 5-7, 16, 27, 28, 30, 31] and a series of researches was done to fabricate such structures [32][33][34][35][36].…”