Direct Laser Writing of Air-Stable p-n Junctions in Graphene

Photo-oxidation of spin-cast films of 6,13-bis-(triisopropylsilylethynyl) pentacene has been exploited to develop a novel means of spatially modulating doping in graphene. The degree of n-doping of initially p-type graphene can be varied by laser irradiation time or intensity with carrier density change up to similar to 7 x 10(12) cm(-2). This n-doping approach is demonstrated as an effective means of creating p-n junctions in graphene. The ability to direct-write arbitrary shapes and patterns of n-doped regions in graphene simply by scanning a laser source should facilitate the exploitation of p-n junctions for a variety of electronic and optoelectronic device applications.