磷酸处理对多孔SiO_2薄膜质子导电特性和双电层薄膜晶体管性能的影响

Effects of H_3PO_4 Treated Porous SiO_2 on Proton Conductivity and Performances of EDL-TFTs

采用等离子体增强化学气相沉积法(PECVD)制备了多孔SiO2薄膜,系统地研究了不同浓度磷酸处理对多孔SiO2薄膜的质子导电特性、双电层电容和以此多孔SiO2薄膜为栅介质的铟锌氧(IZO)双电层薄膜晶体管性能的影响。结果表明:多孔SiO2薄膜的质子电导率和双电层电容随磷酸浓度升高而增大,60%浓度磷酸处理后多孔SiO2薄膜质子电导率和双电层电容分别达到1.51×10-4 S/cm和6.33μF/cm2。随磷酸浓度升高,双电层薄膜晶体管的工作电压降低,并且,电流开关比也变大。其中60%浓度磷酸处理后器件工作电压为1.2 V,迁移率为20 cm2/(V·s),电流开关比为4×106。这种双电层薄膜晶体管有望应用在化学和生物传感等领域。

Porous SiO2 films were deposited by plasma enhanced chemical vapor deposition and were treated by H3PO4 solution with various concentrations. Then indium-zinc-oxide （IZO） electric-double-layer thin-film transistors （EDL- TFTs） were fabricated by using such porous SiO2 films as the gate dielectrics. The effects of H3PO4 treatments on the proton conductivity and EDL capacitance of porous SiO2 films and on the performances of EDL-TFTs were investigated systematically. The proton conductivity and EDL capacitance of SiO2 films increase with the H3PO4 concentration increase. A high proton conductivity of 1.51 × 10-4 S/cm and a large EDL capacitance of 6.33 μF/cm2 are obtained for porous SiO2 films which were treated with 60% H3PO4 solution. The operating voltage decreases and the on/off ratio increases with the increasing H3PO4 concentration. The EDL-TFTs gated by porous SiO2 films treated with 60% H3PO4 solution show the best performance with a low operating voltage of 1.2 V, a high mobility of 20 cm2/（V·s）, and a large on/off ratio of 4× 10^6. Such EDL-TFTs are promising for biosensors and chemical sensors in the future.