2019/08/28 by Zhuofa Chen, Nathan Ullberg, Chen, Zhuofa +7
Computer Science · Materials Science · Physics and Astronomy · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Graphene research and applications #Quantum Information and Cryptography #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.1908.10961
openalex publication_date 2019/08/28 · openalex created_date 2019/09/05 · openalex updated_date 2026/07/28
Avoiding charge density fluctuations and impurities in graphene is vital for high-quality graphene-based devices. Traditional characterization methods require device fabrication and electrical transport measurements, which are labor-intensive and time-consuming. Existing optical methods using Raman spectroscopy only work for doping levels higher than ~1012 cm-2. Here, we propose an optical method using Raman 2D peak-splitting (split between the Raman 2D1 and 2D2 peaks at low doping levels). Electrostatically gated Raman measurements combined with transport measurements were used to correlate the 2D peak-split with the charge density on graphene with high precision (2x1010 cm-2 per 2D peak-split wavenumber). We found that the Raman 2D peak-split has a strong correlation with the charge density at low doping levels, and that a lower charge density results in a larger 2D peak-split. Our work provides a simple and non-invasive optical method to quantify the doping level of graphene from 1010 cm-2 to 1012 cm-2, two orders of magnitude higher precision than previously reported optical methods. This method provides a platform for estimating the doping level and quality of graphene before fabricating graphene devices