Study Of Low-Voltage IZO-Based Oxide Thin Film Transistors

With the development of the portable mobile electronic devices and the new di-splay technology, the low-voltage oxide thin film transistor have attracted numerousresearchers’ attention.the working voltage of the oxide thin film transistor is more th-an20V in the past, and it makes the device has great power consumption in thepro-cess of use. so the high working voltagewill not only raise the cost of deviceuse, but also inconvenience to users because of he or she have to recharged for thedevice constantly. Therefore, reduce the working voltage of oxide thin filmtransistor has very important significance. The working voltage of thin filmtransistor is determine-ed by the threshold voltage, and the size of the thresholdvoltage is main determined by the gate dielectric materials of the divices, Soselection the suitablely gate dielec-tric layer material is the key of low workingvoltage of the oxide thin film transistor. the gate dielectric materials of Low-voltageoxide thin film transistor is mainly inclu-ded the high dielectric constant materialand solid electrolyte materials at present. The gate dielectric material with highdielectric constant has larger capacitance, it can reduce the working voltage of thedevice. And the solid electrolyte materials can formed a equivalent capacitor withelectric double layer effect,and the equivalent capacitor has a has highcapacitance,it can reduce the working voltage of device effectively.This paper mainly introduces the preparation of low-voltage oxide thin filmtransistor by two different ways, and analyzed its relevant properties and. One wayis to use the Al₂O₃films with high dielectric constant which prepared by ALD asagate dielectric materials for the Low-voltage oxide thin film transistor; Anotherway is to use the micro-porous SiO₂inorganic solid electrolyte film which preparedby PECVD as the gate dielectric materials of Low-voltage oxide thin film transistor.The main content of the paper summarized as follows：Using ALD prepared Al₂O₃film in different deposition temperatures as thegate dielectric to prepared TFT, and tested the gate capacitance, according to thesize of the capacitance we can calculated the dielectric constant. The experimentalresults show that the deposition in high temperature can improve dielectric constantof Al₂O₃films, middle the other performance of devices Affected by temperature，we chosen200℃as best deposition temperature for gate dielectric layer. oxide thin film transistor are fabricated on glass substrates by one shadow mask process.TheIZO channel and all IZO electrodes（gate,source,and drain） can be depositedsimultane-ously on Al₂O₃gate dielectric by only one shadow mask during RFmagnetron spu-ttering deposition. The TFTs exhibit a good performance with anlow operation voltage of5V, a field-effect mobility of4.2cm²/Vs, a subthresholdswing of290mV/decade, and a large on-off ratio of2×10⁵.With silane and oxygen as gas source, we preparedf the SiO₂thin films byPECVD,which have columnar microporous structure,and the special structure canmakes double electric layer effect. We use this porous SiO₂thin films with doubleelectric layer effect as a gate dielectric materials to prepare TFTs,and device showsgood performance with an low operation voltage of1V, a field-effect mobility of24.2cm²/Vs, a subthreshold swing of180mV/decade, and a large on-off ratio of1.2×10⁶.Both low-voltage oxide thin film transistor has superiorf electrical performance,and also has the very good light transmittance and stability, so that it can meet therequirements for the development of modern electronic products,and has a verygood application value.