Lithography-free fabrication of graphene devices

We have developed a lithography-free, all-dry process for fabricating graphene devices using an ultrathin quartz filament as a shadow mask. This technique, which is free of the possible contamination of graphene during lithographic process, is simple to implement, versatile, and capable of achieving high throughput. We prepared devices for electrical transport as well as planar tunnel junction studies of n-layer graphene (nLG), with n=1,2,3, and higher using this technique. We observed possible weak localization behavior and an apparent reduction of density of states near the Fermi energy in nLG.