Tunable stress and controlled thickness modification in graphene by annealing

TL;DR

This study investigates how annealing induces tunable stress and modifies thickness in graphene, using Raman spectroscopy to analyze process-induced defects and stress, with potential applications in device performance enhancement.

Contribution

First experimental analysis of process-induced defects and stress in graphene using Raman spectroscopy, demonstrating controllable stress and thickness modifications through annealing.

Findings

Compressive stress up to 2.1 GPa induced by annealing with SiO2 deposition.

Tensile stress of ~0.7 GPa achieved with silicon capping layer.

Stress and thickness can be controlled by annealing temperature and deposition methods.

Abstract

Graphene has many unique properties which make it an attractive material for fundamental study as well as for potential applications. In this paper, we report the first experimental study of process-induced defects and stress in graphene using Raman spectroscopy and imaging. While defects lead to the observation of defect-related Raman bands, stress causes shift in phonon frequency. A compressive stress (as high as 2.1 GPa) was induced in graphene by depositing a 5 nm SiO2 followed by annealing, whereas a tensile stress (~ 0.7 GPa) was obtained by depositing a thin silicon capping layer. In the former case, both the magnitude of the compressive stress and number of graphene layers can be controlled or modified by the annealing temperature. As both the stress and thickness affect the physical properties of graphene, this study may open up the possibility of utilizing thickness and stress engineering to improve the performance of graphene-based devices. Local heating techniques may be used to either induce the stress or reduce the thickness selectively.