Quantitative Estimation of p- and n-Doping Effects on Electrophysical and Optical Properties of CVD Graphene

The ability to alter graphene electronic properties in a controllable way is crucial for development and prosperity of various graphene-based applications and adjacent fields of research. In our work, the Fermi level of chemically vapor-deposited graphene was controlled using a non-destructive and effective method based on thermochemical deposition of a doping substance. Using FeCl3 and Co(C5H5)(2) crystalline powders, both p- and n-type dopings of graphene were realized, respectively. The corresponding doping levels were estimated with Raman spectroscopy, optical absorption spectroscopy, thermoelectric measurements, and sheet resistance measurements. The maximum shift of 0.5 eV from initial undoped graphene to both valence and conduction bands was achieved by cobaltocene and iron chloride dopants, respectively. Simultaneously, a high transparency of more than 96% with sheet resistance as low as 317 Omega per square with p-type conductivity was obtained by FeCl3 doping, and a Seebeck coefficient as high as -28.5 mu V/K was obtained by Co(C5H5)(2) doping.