Superlow-voltage double-layer transistor research has made initial progress

Thin-film transistors (TFTs) are an important type of semiconductor device and have a wide range of application values ​​in flat panel displays, sensors, and the like. In recent years, wide-bandgap oxide semiconductors have attracted people's extensive interest in the field of thin-film transistors due to their advantages of low temperature film formation, high electron mobility, and visible light transparency. Due to the weak capacitive coupling of the conventional SiO2 gate dielectric, the typical operating voltage of the current thin film transistor is generally greater than 10V, which greatly limits its application in the portable field. Studies have shown that ionic liquids, ion gels (IonGels) have low-frequency electric double layer capacitors up to 10μF/cm2. The researchers used this kind of double layer gate dielectric to fabricate an organic thin film transistor with a working voltage of only 1.0V-2.0V. But so far, this type of gate dielectric is rarely used for the development of inorganic oxide semiconductor transistor devices.

Since 2009, the Wanqing Research Group of the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences has observed a large electric double layer capacitance in a microporous film system composed of nano-SiO2 particles, and successfully developed a high-performance, dielectric film as a gate dielectric. A low-voltage transparent thin-film transistor with an operating voltage of less than 1.5 V (Appl. Phys. Lett. 95, 152114 (2009); Appl. Phys. Lett. 96, 043114 (2010)). The paper was featured by NatureAsia Materials, entitled Transparent transistors: lowpower, high performance. On this basis, the research team succeeded in developing a high-performance paper transistor using a room temperature process on a paper substrate, and achieved transistor-enhanced and depletion-mode control (IEEE Trans. Electron Devices, 57, 2258 (2010)). In addition, the research group also introduced Li, H and other ions in the SiO2 nanoparticle film through a simple soaking method, which significantly enhanced the electric double layer capacitance value of the gate dielectric. Subsequently, an ultra-low voltage oxide double layer thin film transistor having a vertical structure was successfully developed (IEEE Electron Device Letters, 31, 1263 (2010); Appl. Phys. Lett. 97, 052104 (2010)).

Recently, the research group has independently developed a self-assembling process that uses only a mask plate to deposit ITO channels and ITO source/drain electrodes on a double-layer gate dielectric to complete transistor fabrication. (IEEE Electron Device Letters. 31, 1137 (2010)). In addition, the research group also used a single SnO2 nanowire as a transistor channel to successfully develop an ultra-low voltage, fully transparent nanowire double layer transistor (Journal of Materials Chemistry, 20, 8010 (2010)).

The above-mentioned oxide semiconductor based ultralow voltage electric double layer transistor has wide application value in the field of low cost, portable sensing, and display devices.