An extended Hückel theory based atomistic model for graphene nanoelectronics

Abstract

An atomistic model based on the spin-restricted extended Hückel theory (EHT) is presented for simulating electronic structure and I-V characteristics of graphene devices. The model is applied to zigzag and armchair graphene nano-ribbons (GNR) with and without hydrogen passivation, as well as for bilayer graphene. Further calculations are presented for electric fields in the nano-ribbon width direction and in the bilayer direction to show electronic structure modification. Finally, the EHT Hamiltonian and NEGF (Nonequilibrium Green's function) formalism are used for a paramagnetic zigzag GNR to show 2e 2 /h quantum conductance.

Field modulation in bilayer graphene band structure

“…The detailed model has been described in Ref. [11]. The EHT parameters are transferable for different systems and have been benchmarked with the graphene band structure using generalized gradient approximation in the density function theory.…”

Doping induces large variation in the electrical properties of MoS2 monolayers

“…The test structure configuration is simulated in QuantumWise Virtual Nanolab Atomistix ToolKit (ATK) package [17] with the semi-empirical Extended Hückel Theory (EHT) method instead of the density functional-theory (DFT) method. This is because: first, density functional-theory (DFT) based models are computationally prohibitive for systems having more than about 200 atoms [18]; second: the semi-empirical EHT method seems to be a good tradeoff, since it is computationally inexpensive and can capture the electronic and atomic structure effects present in more rigorous methods [18].…”

Graphene-based non-Boolean logic circuits

“…These atomic orbitals are approximated with Slater Type Orbitals [33]. The matrix elements of the Huckel Hamiltonian (H) are then described by the following equations [34][35]: H i, i = -V i and…”