Laser‐Assisted Nanowelding of Graphene to Metals: An Optical Approach toward Ultralow Contact Resistance

The electrical performance of graphene‐based devices is largely limited by substantial contact resistance at the heterodimensional graphene–metal junctions. A laser‐assisted nanowelding technique is developed to reduce graphene–metal (G–M) contact resistance and improve carrier injection in suspended graphene devices. Selective breakdown of CC bonds and formation of structural defects are realized through laser irradiation at the edges of graphene within the G–M contact regions in order to increase the chemical reactivity of graphene, facilitate G–M bonding, and, therefore, maximize interfacial carrier transportation. Through this method, significantly reduced G–M contact resistances, as low as 2.57 Ω µm are obtained. In addition, it is demonstrated that the location of laser‐induced defects within the contact areas significantly impacts the interfacial properties and the carrier mobility of graphene devices. A fourfold increase in photocurrent is observed in the suspended graphene photodetectors with treated G–M interfaces as compared to ordinary ones. This contact‐free and position‐selective technique minimizes the degradation of the graphene channels and maintains the superior performance of graphene devices, making it a promising approach for reducing G–M resistance in the fabrication of graphene‐based devices.