Lithography-Free Confinement of 2-D Materials Using Precision Laser Ablation

The ever-expanding array of two-dimensional materials and heterostructures susceptible to alteration in oxygen environments motivates the search for lateral confinement techniques outside conventional lithographic and etching methods. Laser ablation of such materials using a femtosecond pulsed Ti:Sapphire laser and programmable x-y stage is a single-step process that can in principle be used as a flexible tool for device processing. However, scanning probe analysis of sub-micron graphene ribbons fabricated with this technique reveals considerable defect accumulation under ambient condition. We show that such defects are largely alleviated by the simple change in the ablation environment from air to water.