Chemical-Vapor-Deposited Graphene as a Thermally Conducting Coating

Abstract

We performed scanning thermal microscopy measurements on single layers of chemical-vapor-deposited (CVD) graphene supported by different substrates, namely, SiO2, Al2O3, and PET using a double-scan technique to remove the contribution to the heat flux through the air and the cantilever. Then, by adopting a simple lumped-elements model, we developed a new method that allows determining, through a multistep numerical analysis, the equivalent thermal properties of thermally conductive coatings of nanometric thickness. In this specific case we found that our CVD graphene is “thermally equivalent”, for heat injection perpendicular to the graphene planes, to a coating material of conductivity keff = 2.5 ± 0.3 W/m K and thickness teff = 3.5 ± 0.3 nm in perfect contact with the substrate. For the SiO2 substrate, we also measured stacks made of 2- and 4-CVD monolayers, and we found that the effective thermal conductivity increases with increasing number of layers and, with a technologically achievable number of layers, is expected to be comparable to that of 1 order of magnitude-thicker metallic thin films. This study provides a powerful method for characterizing the thermal properties of graphene in view of several thermal management applications.

Properties of Graphene-Related Materials Controlling the Thermal Conductivity of Their Polymer Nanocomposites

“…Indeed, different studies reported thermal conductivity values for pristine graphene between 2000 and 5000 W m -1 K -1 , depending on the measurement technique [9][10][11][12][13][14]. However, this outstanding heat conductivity is affected by several parameters, including defectiveness [12,15,16], lateral size [17], number of layers [9,18] and presence of wrinkles [11,19].…”

Heat Transport Control and Thermal Characterization of Low-Dimensional Materials: A Review

“…The determination of the thermal conductivity requires additional modelling, strong assumptions, and several calibration steps on reference samples [ 153 , 154 ]. Despite these difficulties, recent studies have successfully used the SThM technique to quantitatively determine the thermal conductivity of 2D materials, such as graphene [ 143 , 155 , 156 ]. However, SThM is considered to be ideal to investigate heat transport at nanoscale contacts and interfaces with sub-nW and sub-10 nm heat flux and thermal spatial resolution, respectively.…”

“…However, SThM is considered to be ideal to investigate heat transport at nanoscale contacts and interfaces with sub-nW and sub-10 nm heat flux and thermal spatial resolution, respectively. The SThM technique has been employed recently to investigate heat transfer in semiconductor nanostructures, e.g., nanowires [ 115 , 157 , 158 , 159 ], supported thin films [ 145 , 160 , 161 ] and 2D materials [ 142 , 143 , 144 , 146 , 148 , 154 , 155 , 156 , 162 , 163 ]. For instance, recently El Sachat et al [ 144 ] performed high-vacuum SThM measurements to experimentally probe the transition from ballistic to diffusive thermal transport in suspended single-layer graphene.…”

The heat equation for nanoconstrictions in 2D materials with Joule self-heating

“…While nanoscale constrictions are of great importance for their electrical transport characteristics, particularly in the quantum regime [16,17], they also promote enhanced Joule self-heating and thermoelectric coefficients [18][19][20][21]. For such structures, scanning thermal microscopy [4] is an ideal tool to map surface temperatures with spatial resolution of a few nanometres, as applied to carbon nanotubes [22], nanowires [23][24][25][26] and 2D materials [20,21,[27][28][29][30][31][32][33][34][35][36][37].…”