Stress Effects on Temperature-Dependent In-Plane Raman Modes of Supported Monolayer Graphene Induced by Thermal Annealing.

Yuehua Wei,Chuyun Deng,Weiwei Cai,Xiaoming Zheng,Han Huang,Zhenhua Wei,Yue Su,Wei Luo,Gang Peng,Shiqiao Qin,Yangbo Chen,Jinxin Liu,Xueao Zhang

doi:10.3390/nano11102751

Abstract

The coupling strength between two-dimensional (2D) materials and substrate plays a vital role on thermal transport properties of 2D materials. Here we systematically investigate the influence of vacuum thermal annealing on the temperature-dependence of in-plane Raman phonon modes in monolayer graphene supported on silicon dioxide substrate via Raman spectroscopy. Intriguingly, raising the thermal annealing temperature can significantly enlarge the temperature coefficient of supported monolayer graphene. The derived temperature coefficient of G band remains mostly unchanged with thermal annealing temperature below 473 K, while it increases from −0.030 cm−1/K to −0.0602 cm−1/K with thermal annealing temperature ranging from 473 K to 773 K, suggesting the great impact of thermal annealing on thermal transport in supported monolayer graphene. Such an impact might reveal the vital role of coupling strength on phonon scattering and on the thermal transport property of supported monolayer graphene. To further interpret the thermal annealing mechanism, the compressive stress in supported monolayer graphene, which is closely related to coupling strength and is studied through the temperature-dependent Raman spectra. It is found that the variation tendency for compressive stress induced by thermal annealing is the same as that for temperature coefficient, implying the intense connection between compressive stress and thermal transport. Actually, 773 K thermal annealing can result in 2.02 GPa compressive stress on supported monolayer graphene due to the lattice mismatch of graphene and substrate. This study proposes thermal annealing as a feasible path to modulate the thermal transport in supported graphene and to design future graphene-based devices.

Highlights

IntroductionThe realization of these applications is hindered by several critical issues resulting from the fact that the thickness of graphene is much smaller than its average phonon mean free path (50~200 nm) [7,8,9,10]
We systematically investigated the thermal annealing temperaturedependent phonon modes of monolayer graphene supported on substrate by Raman spectroscopy with ambient temperature ranging from 193 K to 303 K
For 773 K annealing, the temperature coefficient suddenly surges to −0.0602 cm−1 /K, which is twofold than that of pristine monolayer sample without any thermal annealing

Summary

Introduction

The realization of these applications is hindered by several critical issues resulting from the fact that the thickness of graphene is much smaller than its average phonon mean free path (50~200 nm) [7,8,9,10]. Among those issues, power dissipation has become a constantly existing challenge on account of the improving packing density in Nanomaterials 2021, 11, 2751. The influence of phonon scattering on carrier mobility can be altered by local temperature, which largely depends on the heat dissipation efficiency of graphene devices. Understanding the thermal transport characteristics of graphene is a necessary step in overcoming the power dissipation challenge in graphene devices

Methods

Results

Conclusion