Probing Electronic\nDoping in CVD Graphene Crystals\nTreated by HNO<sub>3</sub> Vapors

In this work, we\npresent a comprehensive protocol for\nachieving\nhole doping in graphene through exposure to nitric acid (HNO<sub>3</sub>) vapors. We demonstrate gradual p-type surface doping of CVD-grown\ngraphene on a Si/SiO<sub>2</sub> substrate by thermally depositing\nnitric acid molecules to form self-assembled charge transfer complexes.\nDetailed analysis of charge carrier concentration and Fermi energy\nshifts was conducted using Raman, X-ray and ultraviolet photoelectron\nspectroscopies (XPS/UPS). Our methodology, including a novel PMMA\ncoating step, ensures stability and efficiency of the doping process,\nhighlighting its effectiveness in inducing permanent hole doping while\nmaintaining the structural integrity of the graphene.