Effective Mass versus Band Gap in Graphene Nanoribbons: Influence of H-Passivation and Uniaxial Strain

Abstract

A simple model which combines tight-binding (TB) approximation with parameters derived from first principle calculations is developed for studying the influence of edge passivation and uniaxial strain on electron effective mass of armchair graphene nanoribbons (AGNRs). We show that these effects can be described within the same model Hamiltonian by simply modifying the model parameters i.e., the hopping integrals and onsite energies. Our model reveals a linear dependence of effective mass on band gap for H-passivated AGNRs for small band gaps. For large band gap, the effective mass dependence on band gap is parabolic and analytic fits were derived for AGNRs belonging to different families. Both band gap and effective mass exhibit a nearly periodic zigzag variation under strain, indicating that the effective mass remains proportional to the band gap even when strain is applied. Our calculations could be used for studying carrier mobility in intrinsic AGNRs semiconductors where carrier scattering by phonons is the dominant scattering mechanism.

Electronic and optical properties of monolayer InSe quantum dots

“…It was found that the H-passivation behavior could induce tiny alteration in bond length and angle primarily occurred within one atomic row near the passivated edges [33,34]. These effects can be described within the same model Hamiltonian (equation ( 1)) by simply modifying the hopping integrals parameters just in the most edge atoms [35]. The hopping parameters related to s and p orbitals are proportional to the bond length r as T ∝ 1/r 2 according to the Harrison rule [36,37].…”

Band gap engineering in finite elongated graphene nanoribbon heterojunctions: Tight-binding model

“…Consequently, the C-C bond length at the edges is shortened to (1 − δ c )a c , where δ c (3 to 5%) is the compressive strain on the edge C-C bond due to H passivation. 27,33,34 Additionally, N-AGNRs can be classified into three distinct families N = 3p, 3p + 1, 3p + 2, where p is a positive integer and their electronic properties are known to exhibit distinct family splitting. [35][36][37][38][39] For the finite extended AGNR ( Fig.…”

“…[13][14][15] As quasi 1D materials, GNRs are extremely sensitive to their surrounding conditions, which provides a route for manipulating their electronic properties. Additionally, other factors such as finite size effect, 16,17 edge effect, [18][19][20][21][22][23] and the presence of strain [24][25][26][27] could be used to effectively tune the electronic properties GNRs.…”

“…TB approximation is a very simple, reliable, and computationally efficient method for electronic structure calculations and has been used successfully for modelling the electronic, optical and transport properties of carbon-based systems. 18,27,[29][30][31] In this paper, we present a model based on the divide and conquer rule 32 and TB approximation for studying the role of finite size effect on the electronic properties of elongated GNR heterojunctions. In our model, the GNR heterojunction is divided into a left (L) part, middle (M) part, and right (R) part.…”