title: Tunable stress and controlled thickness modification in graphene by annealing.
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 SiO(2) followed by annealing, whereas a tensile stress ( approximately 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.
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 1 Nanyang Walk, Block 5, Level 3, Singapore 637616.
authors.forename: Zhen Hua
authors.initials: ZH
authors.lastname: Ni
authors.forename: Hao Min
authors.initials: HM
authors.lastname: Wang
authors.forename: Yun
authors.initials: Y
authors.lastname: Ma
authors.forename: Johnson
authors.initials: J
authors.lastname: Kasim
authors.forename: Yi Hong
authors.initials: YH
authors.lastname: Wu
authors.forename: Ze Xiang
authors.initials: ZX
authors.lastname: Shen
mesh_terms: D019245:Compressive Strength; D003460:Crystallization / Q000379:methods*; D055119:Elastic Modulus; D006108:Graphite / Q000737:chemistry*; D006244:Hardness; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D046911:Macromolecular Substances; D006108:Graphite