Ultrafast laser patterning of graphene

This paper describes the recent results in ultrafast (femtoseconds and picoseconds) pulsed laser patterning of graphene films (single layer graphene, graphene oxide (GO)). We investigated such effects of nonlinear optical interaction like selective laser ablation of graphene, laser reduction of graphene oxide and local functionalization (oxidation) of graphene based on multiphoton absorption for microelectrode patterning. The graphene oxide and reduction was demonstrated under femtosecond laser pulses as well as fine ablation for monolayer GO films under ps laser pulses. We demonstrated the patterned laser reduction over the GO film leads to minimum in resistance for laser fluence because of interplay of chemical and thermal effects in carbon lattice and photons. The micro-scale patterns in graphene on SiO2 substrates were fabricated using ultrashort 515 nm laser pulses. For both picosecond and femtosecond laser pulses two competitive processes, based on photo-thermal (ablation) and photochemical (oxidation/etching) effects, were observed. The laser-induced etching of graphene starts just below the threshold energy of graphene ablation. The mechanisms of ultrafast laser interaction with graphene are discussed. Patterned graphene was investigated by AFM, microRaman, SEM and sheet resistance measurements and other techniques. The mechanisms of ultrafast laser interaction with graphene are discussed. The comprehensive models of graphene oxidation/reduction are suggested.