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. [ABSTRACT FROM AUTHOR]