Conductivity improvement of CVD graphene through ITO nanoparticles and Raman characteristics

The combination of a simple and environmentally friendly electroless deposition method with a subsequent vacuum annealing has been successfully used to decorate the chemical vapor deposition (CVD) grown graphene with 10 wt. % tin-doped indium tin oxide (ITO) nanoparticles. A stable sol of ITO was synthesized by using In(NO3)3.H2O and SnCl4, and without using organic binders. The monolayer graphene synthesized by CVD and subsequent dipping in the ITO solution followed by air drying can be easily transferred to SiO2/Si substrate. The crystallization of the ITO nanoparticles was achieved by the vacuum annealing of decorated graphene on SiO2/Si at 450 °C for 1 hour. The ITO nanostructure shows unique architecture on CVD graphene, with uniformly dispersed individual ITO nanoparticles with 25–35 nm size as well as the aggregated nanoparticles with 100–150 nm size which are actually consist of tiny ITO nanoparticles. The ITO nanoparticle decorated-graphene shows 25.6–29.7 % electrical conductivity improvement with 92.70% optical transmittance at 550 nm wavelength. Moreover, the ITO nanoparticles affect the whole Raman signatures to be red-shifted, in which, D, G, and 2D peaks were red shifted by 5.65, 5.69 and 9.74 cm⁻¹ respectively.