| Nanowelding is a key technology for constructing and assembling functional nanodevices.The advantages of laser nanowelding technology based on photothermal effect include low cost,high precision and zero contact pollution,making it attract extensive attention.In this thesis,critical-power laser nanowelding technology for fusing and welding semiconductor nanowires as well as welding semiconductor nanowires and substrates is proposed.The widths of fusing gaps of nanowires range from a few nanometers to hundreds of nanometers under laser power lower than 200 mW.We complete welding of V-shaped,T-shaped,1-shaped nanowire junctions and fail in X-shaped junctions.Meawhile,we use simulation calculation to reveal their mechanism more deeply.The feasibility of using laser nanowelding technology to connect different substrates and semiconductor nanowires was explored.The connection between semiconductor nanowires and gold electrodes was achieved and electrical tests were conducted.The resistance of silicon carbide nanowires was about 181.8 2.The nano-cantilever was fabricated by welding the nanowire and substrate and we verified its good mechanical stability.Observing the protrusions and recessed circular holes on the substrate caused by laser nanowelding with SEM,we found that the aperture diameter under laser power of 120 mW was about 435-574 nm while the aperture diameter under laser power of 107 mW was about 149-184 nm.Furthermore,based on the laser nanowelding technology,three-dimensional helical gold nanostructures with other materials are processed into three-dimensional functional nanodevices and their performances are characterized by means of nano-manipulating.We achieve the nanospring whose maximum elastic stretch is 43%of original length,the nanobridge,the hyperelastic nanocantilever which can withstand over 105 rounds of vibration tests,the nanocoil and the piezoresistive nanosensor with a corresponding resistance of 19.23-22.73 Ω under the elastic deformation which is 0%-34%of original length,etc.Finally,we summarize and prospect the future application of the laser nanowelding technology. |
