Effects of Divacancy and Extended Line Defects on the Thermal Transport Properties of Graphene Nanoribbons

Abstract

The effects of divacancy, including isolated defects and extended line defects (ELD), on the thermal transport properties of graphene nanoribbons (GNRs) are investigated using the Nonequilibrium Green’s function method. Different divacancy defects can effectively tune the thermal transport of GNRs and the thermal conductance is significantly reduced. The phonon scattering of a single divacancy is mostly at high frequencies while the phonon scattering at low frequencies is also strong for randomly distributed multiple divacancies. The collective effect of impurity scattering and boundary scattering is discussed, which makes the defect scattering vary with the boundary condition. The effect on thermal transport properties of a divacancy is also shown to be closely related to the cross section of the defect, the internal structure and the bonding strength inside the defect. Both low frequency and high frequency phonons are scattered by 48, d5d7 and t5t7 ELD. However, the 585 ELD has almost no influence on phonon scattering at low frequency region, resulting in the thermal conductance of GNRs with 585 ELD being 50% higher than that of randomly distributed 585 defects. All these results are valuable for the design and manufacture of graphene nanodevices.

Anomalous Thermal Response of Graphene Kirigami Induced by Tailored Shape to Uniaxial Tensile Strain: A Molecular Dynamics Study

“…The thermal conductivity of SKG (2.9 W/mK) and QSS (1.2 W/mK) models were found to be much lower than that of pristine graphene sharing the same length of 30 nm (259.6 W/mK) and 50 nm (407.2 W/mK), respectively, but was in considerable agreement with previous studies by Wei et al (5.1 W/mK) [11]. The reduction in thermal conductivity of KGS was attributed to the phonon scattering at the vacancy regions [33][34][35][36] and the decrease in real cross-section area [11].…”

“…The vector arrows labeled by blue rows show the migration and loss of heat flux as well as phonon scattering around the vacancy regions. Similar to the defect effect [33][34][35][36][37], the phonon scattering occurs when heat flux passes through a vacancy barrier, which results in the reduction of the thermal conductivity. Especially for the QSS model (see Figure 7b), the transfer direction of partial vector rows was opposite to that of global heat flux.…”

Near-Interface Defects in Graphene/H-BN In-Plane Heterostructures: Insights into the Interfacial Thermal Transport

“…The intrinsic defects include the SW defect, monovacancy defect, double-vacancy defects (such as 585 and f5f7) and line defects. They have their own unique structures and formation energy levels, as well as thermal stability at room temperature [ 38 , 39 , 40 ]. The SW defect involves the transformation of four hexagons into two pentagons and two heptagons by rotating one of the C–C bonds by 90°, and its formation energy is about 5 eV.…”

“…The nonequilibrium Green’s function is an effective method for studying quantum heat transport in nanosystems [ 40 , 50 ]. In this method, the Landauer formula [ 51 ] is used to calculate the thermal conductance.…”

Edge Doping Engineering of High-Performance Graphene Nanoribbon Molecular Spintronic Devices

“…Zigzag-edged graphene nanoribbons (ZGNRs) are particularly promising due to the presence of electric field effect tuning of the spin-polarized edge states [ 20 , 21 ]. The ZGNRs can be further designed into nanodevices with unusual transport behaviors, such as thermal regulation [ 22 ], spin filtering [ 7 ], spin diode [ 21 ] and NDR [ 23 ] effects, using a plethora of strategies, including edge modifications [ 24 , 25 ], doping [ 26 , 27 ] and a applying magnetic field [ 28 ]. ZGNRs thus represent a versatile designer platform to explore the design of high-performance spintronics devices with novel functionalities.…”