Electrospinning Fabrication Of Nanofiber Oxide Transistor And Its Sensing Characteristics

In recent years,field-effect transistor(FET)-type gas sensors have received widespread attention because they can perform ultra-sensitive and reliable gas detection at room temperature.One-dimensional(1D)metal oxide semiconductor(MOSs)nanofibers have been widely used in gas sensors due to their highly active specific surface area,unique electron transport channels,and excellent physical and chemical stability.Therefore,the study of nanofiber FET gas sensors is of great significance.However,the electrical performance and bias stability of the FET are also important factors that restrict the gas sensing performance.In addition,gas sensitivity and selectivity are still key issues for FET-type gas sensors.In order to realize the preparation of high-sensitivity and reliability FET-type gas sensor and improve the gas sensing performance,related research work has been completed in this paper.The main research contents and innovations are as follows:(1)High-performance and stability FETs based on lanthanum(La)doped In₂O₃(LaInO)nanofibers.The In₂O₃ nanofibers FETs have poor electrical performance and stability due to more oxygen vacancy defects.In the work,La doped In₂O₃nanofibers are fabricated as the channel layer to reduce the oxygen vacancies and density of the interface trap states,which is clearly confirmed by investigating the stability under positive bias stress(PBS)and the capacitance voltage(C-V)for FETs.The In₂O₃nanofiber FETs optimized by 5 mol.%La doping exhibits an excellent superior electrical performance with a mobility of 4.95 cm²/Vs and an on/off current ratio of 1.1×10⁸.Furthermore,the threshold voltage offset(?V_TH)of the LaInO nanofiber FETs under PBS has also been decreased from 13.52 to 0.38 V.In order to further enhance the electrical performance of LaInO nanofiber FETs,the high dielectric constant Zr Al O_x film is employed as the LaInO nanofiber FETs insulator.The LaInO nanofiber FETs with Zr Al O_x insulator shows a high mobility of 13.5cm²/Vs and a small subthreshold swing(SS)of 0.18 V/dec.(2)Complexation reaction and Y doping simultaneously improve the performance of low-cost,green and environmentally friendly Sn O₂ nanofiber FETs.Most Sn O₂ nanofibers FETs have poor interface contact quality,which seriously affects the performance of the device.Here,we have proposed that the introduction of Y is used to reduce the O vacancies in the channel layers and ethanolamine(EA)is selected as the complexing agent to enhance the interface property.As a result,the oxygen vacancy concentration of Sn YO nanofiber FET is reduced from 73.9 to 29.6%and the maximum trap density is reduced from 1.51×10¹² to 9.28×10¹¹cm^-2.It is confirmed that the Sn YO nanofibers FETs based on the EA addition exhibit the better electrical performance,including a mobility of 2.70 cm²/V·s and a threshold voltage of 2.3 V.Among them,the mobility is increased by nearly 10 times compared with that without adding EA.(3)Electrospun Yb-doped In₂O₃(InYbO)nanofibers FETs for highly sensitive ethanol sensors.Due to its poor stability and performance,In₂O₃ nanofiber FET has affected its further application in gas detection.In this work,the ethanol gas sensors based on Yb doped In₂O₃ nanofibers FETs are fabricated by a simple and fast electrospinning method.For the optimized In₂O₃nanofibers FETs with a doping concentration of 4 mol.%show the better electrical performance,including a high mobility of 6.67 cm²/Vs,an acceptable threshold voltage of 3.27 V and a suitable an on/off current ratio of 10⁷,especially the enhanced bias stress stability(?V_TH=1.79V).When employed in the ethanol gas sensors,the gas sensors exhibit the enhanced stability and improved sensitivity with a high response of 40 to 10 ppm,which is remarkably higher than that of previously reported ethanol gas sensors.Moreover,the InYbO nanofibers FETs sensors also demonstrate a low limit detection of 1 ppm and improved sensing performance ranging from the sensitivity to the ability of selectivity.(4)Acetone gas sensors employing green-solvent-processed aligned Nd-doped In₂O₃(InNdO)nanofiber field-effect transistors.The MOSs nanofibers used in FETs usually exist in the form of random fibers,which limits the further improvement of gas sensing performance.In addition,the precursor solvents used are all organic and toxic.Here,we propose the green-solution-processed electrospinning technique to construct Nd-doped In₂O₃ aligned nanofiber array.Benefit for electron transport,the FET based on InNdO nanofiber array exhibits s a high mobility of 5.5 cm²/Vs and a suitable an on/off current ratio of 10⁷.As a result,when employed in the acetone gas sensors,the gas sensors demonstrate the excellent performance for acetone detection at room temperature,including extremely high response(88 under 4 ppm),rapid response and recovery time(31/53 s),relative low limit of detection(69 ppb)and outstanding selectivity to acetone gas.In addition,the acetone sensing mechanism is further probed with the C-V analysis.