Graphene patterning, i.e., etching graphene film into certain micro/nano structures, is a significant step in fabricating graphene-based electronic, optoelectronic elements for both fundamental studies and industrial applications. In this thesis, we have for the first time proposed to pattern graphene film by magnetic-assisted UV ozonation based on the paramagnetic property of oxygen molecules/radicals.

we have successfully patterned chemical vapor deposition (CVD) grown graphene film by applying an approximately vertical magnetic field (Bz=0.31T,∇Bz=90T∙m^-1) in UV ozonation. In this process, the paramagnetic oxygen molecules and photodissociated oxygen radicals are magnetized, and their random motions convert into directional which can greatly enhance the quality of graphene patterning. Using a ferromagnetic steel mask, we have patterned graphene with a line width of 29 μm and lateral under-oxidation less than 4 μm by reducing lateral diffusion and dissipation of the randomly moved ozone molecules. This solution has been successfully used to fabricate graphene field-effect transistor (FET) arrays with the hole and electron mobilities up to ~1682 cm^2∙V^-1∙s^-1 and ~1316 cm^2∙V^-1∙s^-1.Magnetic-assisted UV ozonation can be a promising solution toward resist-free, substrate non-damaging, and cost effective microscale patterning of graphene film.

This research was published in Yixuan Wu, Haihua Tao*, Shubin Su, Huan Yue, Hao Li, Ziyu Zhang, Zhenhua Ni & Xianfeng Chen*, Patterning Graphene Film by Magnetic-assisted UV Ozonation, Scientific Reports, 7, 46583 (2017).