Significantly improved measurement accuracy in determining the thermal expansion coefficient of single layer graphene

The precise thermal expansion coefficient (TEC) of single layer graphene (SLG) is of vital importance to the preparation and application of graphene-based devices. In this work, a comprehensive Raman investigation on the TECs of SLG was conducted by reducing the effects of defects, native strains, and substrate doping. The TECs of graphene with few defects extracted from Raman spectra remained negative without the appearance of a positive transition in the temperature range of 303-503 K. After eliminating the influence of native strains and substrate doping on the TEC acquisition by excluding the first thermal cycle, a more reliable TEC, (- 3.68 +/- 0.49) x 10(-6)/K, was obtained at room temperature, which was much closer to the theoretical predictions than those results in previous experimental reports. This investigation provides a more precise approach to measure the TECs of two-dimensional materials by Raman spectroscopy.