Engineering the work function of armchair graphene nanoribbons using strain and functional species: a first principles study

Abstract

First principles density functional theory calculations were performed to study the effects of strain, edge passivation, and surface functional species on the structural and electronic properties of armchair graphene nanoribbons (AGNRs), with a particular focus on the work function. The work function was found to increase with uniaxial tensile strain and decrease with compression. The variation of the work function under strain is primarily due to the shift of the Fermi energy with strain. In addition, the relationship between the work function variation and the core level shift with strain is discussed. Distinct trends of the core level shift under tensile and compressive strain were discovered. For AGNRs with the edge carbon atoms passivated by oxygen, the work function is higher than for nanoribbons with the edge passivated by hydrogen under a moderate strain. The difference between the work functions in these two edge passivations is enlarged (reduced) under a sufficient tensile (compressive) strain. This has been correlated to a direct-indirect bandgap transition for tensile strains of about 4% and to a structural transformation for large compressive strains at about - 12%. Furthermore, the effect of the surface species decoration, such as H, F, or OH with different covering density, was investigated. It was found that the work function varies with the type and coverage of surface functional species. Decoration with F and OH increases the work function while H decreases it. The surface functional species were decorated on either one side or both sides of AGNRs. The difference in the work functions between one-sided and two-sided decorations was found to be relatively small, which may suggest an introduced surface dipole plays a minor role.

Strain-engineered direct-indirect band gap transition and its mechanism in two-dimensional phosphorene

“…This linear shift of energy is not unique to phosphorene. It is also observed in other semiconducting nanostructures [28,29,[31][32][33][34][35][36][37][38][51][52][53][54].…”

“…This mechanism has been applied successfully in many other semiconductor nanostructures [28,29,[31][32][33][34][35][36][37][38]. Effective masses of charge carriers (thus carrier mobility) were also found to be drastically tuned by strain.…”

Effect of edge chemistry doping on the transport and optical properties for asymmetric armchair-edge graphene nanoribbons under a uniaxial strain

“…The observed interesting phenomena in the transport properties have been proved by the optical absorption spectra of the system. The present results may provide a valuable guidance to the design of an electromechanical [35][36][37][38][39] device based on the reactive edges [40] of the asymmetric AGNRs.…”

“…Furthermore, Bhattacharya et al [38] have investigated the band-gap variation of AGNRs in way of the first-principles calculation, except for the strain and edge passivation-induced energy gap [39] and work function [40] variations for AGNRs. However, less attention has been paid to the combined effect of strain and edge passivation [38][39][40] on the transport and optical properties [5][6][7][8][41][42][43] of the asymmetric AGNRs.…”

Уменьшение Работы Выхода При Гидрогенизации Углеродных Нанотрубок В Плазме Водорода

“…DOI: 10.21883/PJTF.2018.10. 46099.17236 Взаимодействие водорода с углеродными нанотрубками (УНТ) и графеновыми наноструктурами важно с теоретической и практической точек зрения [1][2][3][4]. Хемосорбированный водород имеет энергию связи порядка 2.8−3 eV [2], поэтому может быть связан с нанотрубкой даже при температурах существенно выше комнатной.…”