Third-harmonic and multiphoton excitation fluorescence microscopy of single and few layer graphene

Single- and few-layer graphene was studied with simultaneous third-harmonic and multiphoton-induced fluorescence microscopy. Both CVD grown and exfoliated graphene were studied [1,2]. The photo-thermal CVD growth was carried out on copper foils in a methane/hydrogen atmosphere, followed by a transfer process. Oxidized silicon substrates were used as the final substrate in both cases. The oxide thickness was 300 nm to achieve maximal contrast in optical microscope. Single- and few-layer graphene areas were identified using optical microscopy and Raman spectroscopy.