J Appl Phys 2011, 110:014302.CrossRef 42.

Zhang Y, Liu F: Maximum asymmetry in strain induced mechanical instability of graphene: compression versus tension . Appl Phys Lett 2011, 99:241908.CrossRef Competing interests The author declares that he has no competing interests.”
“Background Graphene has many unique and novel electrical and optical BIRB 796 properties [1–3] because it is the thinnest sp2 allotrope of carbon arranged in a honeycomb lattice. Recent studies indicate that the remarkable carrier transport properties of suspended graphene with respect to supported graphene include temperature transport, magnetotransport, and conductivity [4–6]. The phonon modes of graphene and their effects on its properties due to the dopants and defects’ effects are also different between suspended and supported graphene. These effects on its properties can be studied by Raman spectroscopy [7–9]. Raman spectroscopy has been CUDC-907 in vivo extensively used to investigate the vibration properties of materials [10–13]. Recently, characterizing the band structure of graphene and the interactions of phonons has been applied as the powerful study method [14–18]. With the different effects influenced by doping and substrate, charged dopants produced by residual photoresist in the fabrication process are possibly induced by the deposition and also affect the substrate. According to relevant studies [19, 20], the properties

of metallic particles on graphene used as an electrode in graphene-based electronic SGC-CBP30 mw devices can be understood clearly and suspended graphene is suitable to use to understand the effect of charged dopants on the substrate. In our previous works [21, 22], we used polarized Raman spectroscopy to measure the strain effect on the suspended graphene. We fitted the spectra with triple-Lorentzian function and obtained three sub-2D peaks: 2D+, 2D-, and 2D0. In another work, we observed three sub-G peaks: G+, G-, and G0. The property of intensity of G+,

G is similar as 2D+ and 2D peaks. The linewidth analysis with data fitting into pure Lorentzian and Voigt profiles had been applied two-photon transitions in atomic Cs [23, 24], because of its elastic motion of atomic structures. Pregnenolone The Voigt profile, a convolution of a Lorentzian and a Gaussian, is used to fit these Raman spectra of graphene. In this work, the supported and suspended graphene were both fabricated by micromechanical cleavage, and then, they were identified as monolayer graphene by Raman spectroscopy and optical microscopy. The Raman signals of suspended and supported graphene can be measured and analyzed by probing the graphene surface which contains them. The peak positions of G band, the I 2D/I G ratio, and bandwidths of G band fitted with Voigt profile are obtained with the Raman measurements. Under our analysis, details about the effects of charged impurities on the substrate can be realized.