Raman analysis of epitaxial graphene grown on 4H-SiC （0001） substrate under low pressure condition

In this paper, we report a feasible route of growing epitaxial graphene on 4H-SiC （0001） substrate in a low pressure of 4 mbar （1 bar=105 Pa） with an argon flux of 2 standard liters per minute at 1200, 1300, 1400, and 1500 ℃ in a commercial chemical vapour deposition SiC reactor. Using Raman spectroscopy and scanning electron microscopy, we confirm that epitaxial graphene evidently forms on SiC surface above 1300 ℃ with a size of several microns. By fitting the 2D band of Raman data with two-Lorentzian function, and comparing with the published reports, we conclude that epitaxial graphene grown at 1300 ℃ is four-layer graphene.