title: Minimizing Unintentional Strain and Doping of Single-Layer Graphene on SiO2 in Aqueous Environments by Acid Treatments.
abstract: The effects of treating SiO2/Si with either acidic or alkaline solutions on single-layer graphene were investigated using Raman microscopy. It is well-known that in air graphene on SiO2 is unintentionally strained and hole-doped to different degrees, varying widely by sample. It is also known that various amine compounds act as electron donors to graphitic materials. In this study, a SiO2/Si substrate was simply dipped in either a concentrated HCl solution or pH 9.0 NaOH solution and then rinsed, prior to transferring graphene on it. The G and 2D peaks were followed at a fixed position on a single-layer graphene flake in water and various concentrations of pH 7.4 tris(hydroxymethyl)aminomethane (Tris) buffer. The results demonstrate that these treatments reduce the sample variation, improve the stability against Tris, and even bring some graphene samples close to a freestanding state. The Raman analysis reveals that the main effect of dipping is to relieve strain. The undoping effect on some samples is explained by the HCl solution becoming trapped between the graphene and SiO2 surface.
authors: Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, Yamagata 992-8513, Japan.
authors: Katsuya
authors: K
authors: Masuda
authors: Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, Yamagata 992-8513, Japan.
authors: Masahito
authors: M
authors: Sano