Session: Research Posters

Paper Number: 114286

114286 - Thermal Transport Properties of Bilayer Graphene With Different Twist Angles 

Two-dimensional (2D) materials have been extensively studied and exploited in various fields such as electronics, sensors, bioengineering, energy storage, and conversion technology due to their excellent electronic, optical, and thermal properties. Specifically, in recent years, they become emergent thermal and thermoelectric materials with the potential widespread in wearable electronics applications. Due to their potential promising applications, it is of significance to discover the thermal transport properties of 2D materials with different twist angles, and thus tune 2D materials’ thermal properties and use this tunability to develop novel 2D devices with high performance. It has been theoretically predicted that when bilayer graphene’s twist angle is tuned, their thermal conductivities will increase due to the interlayer phonon interactions. This theory has not been verified by the experiment yet.

In this work, opto-thermal Raman method is used to study the impact of twist angle on the thermal properties. We first utilize more direct measurements of the optical absorption, and then by comparing the response of the samples using different laser spot sizes, we are able to measure the thermal conductivities. Then thermal conductivities at different twist angles are obtained providing more scientific merits.

The Raman opto-thermal technique has been the most successful method for the measurement of thermal conductivity of 2D materials and was used to measure the 2D materials at different twist angles. In this technique, a laser is focused at the center of graphene Moiré patterns and used to measure the peak position of a Raman-active mode. As the laser power is increased, the sample is heated which enables red-shift Raman mode due to thermal softening. Another group of experiments is conducted by placing the samples on a heating platform and monitoring the change of Raman-active mode peak position shift. Combining these two sections of experiments provides us with thermal modeling that can then be used to extract the thermal conductivity from the measured shift rate. We have used a refined version of the opto-thermal Raman technique to study the thermal conductivity of bilayer graphene at different twist angles.

In conclusion, we have used Raman opto-thermal technique to study the thermal transport properties of bilayer graphene at different twist angles. This work addresses several important issues in the measurement of thermal conductivity of graphene using Raman spectroscopy. We derive the thermal conductivity values at different twist angles. These results are of significance to discovering the thermal transport properties of graphene, and thus develop efficient 2D thermal materials which needs thermal properties’ tuning.

Presenting Author: Xian Zhang Stevens Institute of Technology

Presenting Author Biography: Assistant Professor at Stevens Institute of Technology.

Authors:

Yingtao Wang Stevens Institute of Technology
Xian Zhang Stevens Institute of Technology