Electrospinning Preparation Of Indium Oxide Nanofibers And Its Application In Field Effect Transistors

Recently,the rapid development of silicon semiconductor industry has led to remarkable decrease in the size of field-effect transistors?FETs?,while at the same time enabling power reduction,performance improvement and on-chip integration.However,with the decrease of the characteristic size of the devices into nano-scale,existing processes and materials are no longer applicable.In recent years,one-dimensional?1D?nanostructures have attracted extensive attention due to their distinctive transport characteristics,large surface-to-volume ratio,and superior mechanical flexibility.As one of the representative metal oxide semiconducting materials,1D indium oxide?In₂O₃?nanostructures have been widely explored as channels in FETs.To achieve high-performance FETs based on In₂O₃ nanofibers,we focus on the following topics:1.High-performance FETs based on gadolinium?Gd?doped In₂O₃?InGdO?nanofibers and the inverters.Most of the FETs based on In₂O₃ nanofibers usually operate in depletion mode,which lead to large power consumption and complicated integrated circuit design.In this report,InGdO nanofibers networks were fabricated by electrospinning and applied as the channels in the FETs.Upon the optimization of the doping levels and the nanofibers density,the device performance could be precisely manipulated.It is found that the FETs based on InGdO nanofibers,with Gd doping concentration of 3%and nanofibers density of 2.9?m^-1,exhibit the best device performance,including a field-effect mobility(?_FE)of 2.83 cm²/Vs,a subthreshold swing?SS?of 2.4 V/decade,a threshold voltage(V_TH)of 5.8 V,and an on/off current ratio(I_on/I_off)of⁴×10⁸.By employing high-k ZrO_x thin films as the gate dielectric in the FETs,the?_FE,SS and V_THH are improved to be 17.4 cm²/Vs,160 mV/decade and 0.7 V,respectively.Finally,a resistor-loaded inverter based on the InGd_3%O nanofibers/ZrO_x FETs was constructed and a gain at 4 V of¹1 is achieved.2.Low-temperature,nontoxic In₂O₃ nanofibers and their application in FETs.For most of the previous reports of nanofibers/nanowires FETs,high-temperature annealing process is imperative to achieve reasonable electrical performance of the devices.This limits its application in flexible electronics.Meanwhile,in those reports,all the precursor solutions were synthesized using organic solvents,which is toxic to humans and harmful to the environment.In this report,the mixture of water-induced?WI?In₂O₃ precursor solution and poly?vinyl alcohol??PVA?were used to fabricate the composite nanofibers by electrospinning.The systematic investigations were performed to reveal the annealing temperature dependence of the FETs performance.It is found that the FET based on WI In₂O₃ nanofibers annealed at 380 ^oC for 1 h?In₂O₃-380-1h?exhibits a field-effect mobility(?_FE)of 1.54 cm²/Vs,and an on/off current ratio(I_on/I_off)of⁸×10⁴.Interestingly,the electrical performance of the FET based on WI In₂O₃ nanofibers annealed at 280^oC for10 h?In₂O₃-280-10h?is comparable with the FET based on In₂O₃-380-1h.To further improve the electrical performance of the FETs processed at low temperature,the FET based on In₂O₃-280-10h as the channel and the aqueous-derived ZrO_x dielectrics as dielectric was integrated.This nontoxic and fully WI approach is highly expected for the fabrication of low-temperature,and flexible circuitry.