Tension-Induced Raman Enhancement of Graphene Membranes in the Stretched State

Kai-Ming Hu; Zhong-Ying Xue; Yun-Qi Liu; Hu Long; Bo Peng; Han Yan; Zeng-Feng Di; Xi Wang; Liwei Lin; Wen-Ming Zhang

doi:10.1002/smll.201804337

Tension-Induced Raman Enhancement of Graphene Membranes in the Stretched State

Small. 2019 Jan;15(2):e1804337. doi: 10.1002/smll.201804337. Epub 2018 Dec 3.

Authors

Kai-Ming Hu¹, Zhong-Ying Xue², Yun-Qi Liu², Hu Long³, Bo Peng¹, Han Yan¹, Zeng-Feng Di², Xi Wang², Liwei Lin⁴, Wen-Ming Zhang¹

Affiliations

¹ State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
² State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China.
³ Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.
⁴ Berkeley Sensor and Actuator Center, University of California at Berkeley, 5101-B Etcheverry, Berkeley, CA, 94720-1774, USA.

PMID: 30506848
DOI: 10.1002/smll.201804337

Abstract

The intensity ratio of the 2D band to the G band, I_2D /I_G , is a good criterion in selecting high quality monolayer graphene samples; however, the evaluation of the ultimate value of I_2D /I_G for intrinsic monolayer graphene is a challenging yet interesting issue. Here, an interesting tension-induced Raman enhancement phenomenon is reported in supported graphene membranes, which show a transition from the corrugated state to the stretched state in the vicinity of wells. The I_2D /I_G of substrate-supported graphene membranes near wells are significantly enhanced up to 16.74, which is the highest experimental value to the best of knowledge, increasing by more than 600% when the testing points approach the well edges.The macroscopic origin of this phenomenon is that corrugated graphene membranes are stretched by built-in tensions. A lattice dynamic model is proposed to successfully reveal the microscopic mechanism of this phenomenon. The theoretical results agree well with the experimental data, demonstrating that tensile stresses can depress the amplitude of in-plane vibration of sp² -bonded carbon atoms and result in the decrease in the G band intensity. This work can be helpful in furthering the development of the method of suppressing small ripples in graphene and acquiring ultraflat 2D materials.

Keywords: G band depression effect; Raman enhancement phenomenon; built-in stresses; intensity ratios; stretched graphene.

Publication types

Research Support, Non-U.S. Gov't