The Welding Of Metal Oxide Nanofibers And Its Application In Field Effect Transistors

Metal oxide nanofibers have drawn great attention due to their specific physical and electrical properties,which exhibit great potential applications in field-effect transistors?FETs?.In recent years,several techniques have been developed to prepare the nanofibers,such as vapor-phase method,liquid-phase method,and template method.Among these methods,electrospinning is found to be superior to others because of its unique advantages,including the relatively low fabrication cost,high-throughput,and the possibility for large-scale fabrication.Moreover,electrospinning can be used to fabricate various nanofibers?e.g.,organics,inorganics and composite materials?.The FETs based on metal oxide nanofibers have been widely studied.However,there are still some issues to be resolved,including?i?poor joint junction among the stacked metal oxide nanofibers and poor adhesion between the nanofibers and the substrate excessively;?ii?excessively high annealing temperature to form metal oxides;?iii?searching for indium-free alternatives.To solve these problems and achieved high-performance FETs,focus on the following topics:1.Self-welding and low-temperature formation of metal oxide nanofibers and its application to electronic devices.In this report,indium oxide?In₂O₃?nanofibers were fabricated by electrospinning using polymethyl methacrylate?PMMA?as polymer and epoxy resin as additive.Benefiting from the excellent chemical properties of PMMA,In₂O₃ nanofibers with impact stacking were prepared at a relatively low annealing temperature by a welding process.The welded In₂O₃ nanofibers were characterized by scanning electron microscopy?SEM?,Fourier transform infrared?FT-IR?and X-ray diffraction?XRD?and the electrical performance of the field-effect transistors?FETs?based on the welded In₂O₃ nanofibers were systematically investigated.It is observed that the FET based on In₂O₃ nanofibers annealed at 320^oC,with a nanofiber density of0.4?m^-1 exhibits high electrical performance,including an on/off current ratio(I_on/I_off)of?5×10⁷,a field-effect mobility(?_FE)of 1.27 cm²/Vs,an on voltage of-8 V and a hysteresis of 5 V.A device array with 4×5 units was fabricated and tested,confirming the excellent reliability and reproducibility of the FET.2.High-performance field effect transistors based on welded SnGaO nanofibers.In this report,the Sn_1-xGa_xO nanofibers with various composition ratios were fabricated by electrospinning and FET based on Sn_1-xGa_xO nanofibers were constructed.The electrical performances of the FETs depending on the composition ratio of Ga to Sn have been systematically investigated.In order to promote the mechanical and electrical performance of the nanowires,the Sn_1-xGa_xO nanowires were welded by introducing polymer mixture containing polyvinyl pyrrolidone?PVP?and PMMA.It is confirmed that the transport of the carriers in Sn_1-xGa_xO nanowires can be effectively promoted by the welding process.Considering all the electrical performance of the FETs,the FET based on welded Ga_0.2Sn_0.8O nanofibers/SiO₂ exhibit optimumed electrical performance.When high-k Zr O_x was integrated into the FETs as the dielectric layer,the FETs based on Sn_0.8Ga_0.2O nanofibers/ZrO_x exhibits high stability and superior performance,including a field-effect mobility of 5.2 cm²/Vs and an on/off current ratio of 1.5×10⁶.The FETs based on Sn_0.8Ga_0.2O nanofibers/ZrO_x would promote the development of low-consumption,low-cost and high-performance indium-free FET devices.