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

Abstract

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.

Graphene Nanoscrolls via Electric-Field-Induced Transformation of Water-Submerged Graphene Nanoribbons for Energy Storage, Nanofluidic, and Nanoelectronic Applications

“…It should be noted that the interfacial interaction between the substrate and the prolonged edges of the GNR should be sufficiently strong to hold the edges in place as the GNR transforms into a nanoscroll. Strong interfacial interactions, attributed to the formation of chemical bonds, between graphene and common substrates such as metals (e.g., Au/Ni, Si, and SiOx) may be experimentally achieved by using various mechanisms like nanoscale welding , and different annealing protocols of rapid thermal annealing and vacuum annealing . Chemical bond formation has also been reported for other substrates such as Cu, Ni, and SiC. − In addition, nonbonded vdW interaction between graphene and its target substrate may also be enhanced by techniques such as inserting a PMMA interlayer on top of SiO 2 and replacing SiO 2 substrate with atomically flat GaAs substrate, which may as well be explored in our proposed setup to fix the position of the prolonged edges.…”

“…It should be noted that the interfacial interaction between the substrate and the prolonged edges of the GNR should be sufficiently strong to hold the edges in place as the GNR transforms into a nanoscroll. Strong interfacial interactions, attributed to the formation of chemical bonds, between graphene and common substrates such as metals (e.g., Au/Ni, Si, and SiOx) may be experimentally achieved by using various mechanisms like nanoscale welding 51,52 and different annealing protocols of rapid thermal annealing and vacuum annealing. 53 Chemical bond formation has also been reported for other substrates such as Cu, Ni, and SiC.…”

Fast Growth of GaN Epilayers via Laser-Assisted Metal–Organic Chemical Vapor Deposition for Ultraviolet Photodetector Applications

“…Laser-assisted MOCVD (LMOCVD) is an ideal method for growth of various materials with the advantages of low growth temperature, fast growth rate, and the capability to deposit patterned materials. − Several semiconductor materials, including silicon, gallium arsenide, indium phosphide, and aluminum nitride, have been successfully grown using LMOCVD. − For instance, Zhou et al reported ultraviolet laser LMOCVD growth of c -oriented GaN films with a broad XRD peak at low temperatures. However, the photolysis of the precursors with a UV laser resulted in the low density of the reactive radicals and a slow GaN growth rate.…”

Laser processing of graphene and related materials for energy storage: State of the art and future prospects

“…As an example, the growth of inorganic nanostructures on CNT and rGO surfaces by direct laser irradiation of nanocarbon mixed with other precursors has been reported, leading to the formation of hybrid materials [112][113][114][115][116][117]. The laser-induced creation of structural defects and openended carbon atoms has allowed the nanowelding of graphene sheets to gold metal contacts at laser fluences below the ablation threshold of graphene [118]. After subsequent thermal annealing, graphene-metal junctions with ultra-low contact resistance were obtained in a precise manner, enabling a substantial performance enhancement in suspended graphene photodetectos.…”