Probing Charged Impurities in Suspended Graphene Using Raman Spectroscopy

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• 作者：Zhen Hua Ni ; Ting Yu ; Zhi Qiang Luo ; Ying Ying Wang ; Lei Liu ; Choun Pei Wong ; Jianmin Miao ; Wei Huang ; Ze Xiang Shen
• 刊名：ACS Nano
• 出版年：2009
• 出版时间：March 24, 2009
• 年：2009
• 卷：3
• 期：3
• 页码：569-574
• 全文大小：298K
• 年卷期：0
• ISSN：1936-086X

文摘

Charged impurity (CI) scattering is one of the dominant factors that affects the carrier mobility in graphene. In this paper, we use Raman spectroscopy to probe the charged impurities in suspended graphene. We find that the 2D band intensity is very sensitive to the CI concentration in graphene, while the G band intensity is not affected. The intensity ratio between the 2D and G bands, I_2D/I_G, of suspended graphene is much stronger compared to that of nonsuspended graphene, due to the extremely low CI concentration in the former. This finding is consistent with the ultrahigh carrier mobility in suspended graphene observed in recent transport measurements. Our results also suggest that at low CI concentrations that are critical for device applications, the I_2D/I_G ratio is a better criterion in selecting high quality single layer graphene samples than is the G band blue shift.