Twist-angle-dependent thermal conduction in single-crystalline bilayer graphene

Abstract

Thermal conductivity (κ) of the single-crystalline bilayer graphene (BLG) is investigated experimentally as a function of the interlayer twist angle (θ) and temperature using the optothermal Raman technique. The results show that a slight 2° twist angle leads to a κ decrease in 15% at ∼320 K. With the regulation of θ from 0° to 30°, the in-plane κ of the BLG decreases first and then increases showing an asymmetry V shape. The local maximum value of κ was reached when the twist angle is 30° and the highest value was found on the Bernal stacked BLG. The obtained κ is further found to be sensitive to the Moire periodicity but insensitive to the commensurate lattice constant of the twisted BLG. The non-equilibrium molecular dynamics simulation reveals that the twist angle in t-BLG affects the proportion of low-frequency phonons and finally changes the κ. The quantitative study validates the regulation of thermal conduction through the interlayer twist angle and favors the further understanding of thermal transport in the van der Waals bilayer systems.

Twist-Angle-Dependent Phonon Transport of van der Waals MoSe2 Thermoelectric Materials for the Recycling of Waste Heat

“…This trend is in accordance with the results of earlier research on the twist thermal conductivity of 2D materials with hexagonal lattice structures. 24,26,65 The thermal conductivity decreases monotonically from 0 to 20°, reaching a minimum at 20°, then increases monotonically from 20 to 30°, reaching a local maximum at 30°, but remains lower than the thermal conductivity at a twist angle of 0°. Further, when the twist angle is in the range of 0 to 5°, a slight twist will result in a significant change in thermal conductivity, but the change in thermal conductivity is less pronounced as the twist angle is in the range of 5 to 25°.…”

Twist angle-dependent work functions in CVD-grown twisted bilayer graphene probed by Kelvin probe force microscopy

“…The multilayer graphene films were synthesised using a modified low-pressure CVD system. 15 A schematic of the experimental CVD setup is shown in Fig. 1(a).…”

“…The multilayer graphene film was grown on copper foil via low-pressure CVD, as previously reported. 15 During the growth, 2 sccm methane (CH 4 ) and 30 sccm hydrogen (H 2 ) were introduced to the chamber at 1030 °C for 40-90 min. After the growth, the chamber was cooled naturally to room temperature in H 2 (30 sccm).…”

“…8,9 The growth of tBLG via CVD is important for the investigation of its angle-dependent physical properties and potential applications. [10][11][12][13][14][15] In addition, it is critical to directly characterise the angle-dependent structural characteristics of tBLG. Recently, transmission electron microscopy, 16,17 micro-Raman spectroscopy, 18,19 and various scanning probe microscopy (SPM) techniques [20][21][22][23][24][25][26] have been widely used to study the Moiré patterns of tBLG samples constructed using artificial stacking methods.…”

High Performance Hall Sensors Built on Chemical Vapor Deposition-Grown Bilayer Graphene

“…The GHEs are fabricated on CVD-grown bi/monolayer graphene through a standard micro–nano processing technology, as shown in Figure a and described in refs and . Bilayer and monolayer graphene samples were grown on copper foils by the CVD method − based on different growth conditions but in the same CVD equipment. The grown bilayer graphene has a hexagonal morphology, as shown in Figure b, and is identified as the bilayer by the Raman measurements (inset in Figure b) after being transferred to the Si/SiO 2 substrate in the following process.…”