Research On Low Voltage Junctionless IZO Thin Film Transistors Based Electrical-double-layer

Recently, oxide-based thin-film transistors (TFTs) have been extensively investigated because of theirhigh electron mobility, low processing lost, compatible with flexible substrates and able to producelarge-area displays. Among various oxide semiconductors, IZO are preferred as a channel layer of TFTsdue to they are deposit at room temperature, and high electron mobility (>10cm2/Vs) even for anamorphous film.In reported paper with IZO TFTs，most TFTs gated by SiNxor SiO2films. the high operating voltage（>20V）is inevitable. Because compact SiO2have low permittivity, causing small capacitance of gatedielectric and high operating voltage. On the other side, papers reported need complicated fabricationprocesses. The fabrication of oxide TFT require multiple steps of deposition, even sophisticatedphotoetching when necessary.Under such this background, these are targeted researches focusing on low operating voltage andprocesses costs. Fistly, mesoporous SiO2protons films were deposited by plasma enhanced chemical vapordeposition (PECVD) technology at room temperature. The research indicates that500nm SiO2film showsa large capacitance (about6.2μF/cm2) at1HZ, much larger the traditional TFTs with thermally grown SiO2in the same conditions. At the same time, the EDL-effect theory is proposed and confirmed by relevantexperiments for interpreting this abnormal physical phenomenon. The conductivity of the SiO2films is5.6×10-5S/cm.Secondly, employed by mesoporous SiO2solid electrolyte as gate dielectric, juntionlessIZO TFT was fabricated that IZO thin films as source/drain electrodes and channel layers by one-stepmask method. These TFTs exhibit a good performance with an ultralow operation voltage of1.5V, asubthreshold swing of110mV/decade, a field-effect mobility of21.5cm2/Vs, a large on-off current ratio of6×106, respectively. The device stability was investigated with the different negative bias and illuminationconditions. Thirdly, juntionless TFT with single/dual in-plane gate was successfully fabricated. Futherly,the device has logical function employed by in-plane gate as signal input and the output source/draincurrent as signal output, which realizes AND logic.The full-room-temperature oxide TFTs by one-shadow-mask process show a lot of advantages，such as lowoperation voltage、simple device process、low cost and so on. Such TFTs are very promising for theapplication of low-power and portable electronic products in the future.