氧化物质子导体薄膜及其在低电压无结薄膜晶体管中的应用

Electric-Double-Layer thin-film transistors (EDLT) are regarded as ideal devices for potential portable sensors because of large EDL capacitance at the dielectric/semiconductor interface and low-voltage operation. In general, EDLT were fabricated using organic proton conductors and organic semiconductors. However, such organic materials usually show a limited chemical stability and durability as well as a low field-effect mobility. To avoid these disadvantages, a novel type of field-effect device, planar junctionless (JL) oxide-based EDLT with relatively simple process will be fabricated using nanogranular Al2O3 and SiO2 proton conducting films as gate dielectrics, and transparent conductive indium-zinc-oxide (IZO) and indium-tin-oxide films (ITO) as electrodes (source and drain) and channel. Influence of moisture, temperature and surface modification of the protons such as H+ and Li+ on the proton conductivity and EDL capacitance of the nanogranular films will be investigated. The mechanism of polarization of the proton conducting films at the proton conductor/channel interfaces will be demonstrated. A physical model for such mechanism of polarization of the oxide proton conducting films will be established. Such JL EDLT gated by such nanogranular Al2O3 and SiO2 proton conductors will exhibit a low operation voltage of ≤1.5 V, a large current on/off ratio of 10^7 and a high field-effect mobility of 40 cm^2/Vos. We will establish an accurate model for the role of oxide semiconductor channel modulation in terms of such devices. This work will provide experimentally and theoretically strong basis and foundation for portable chemical sensors, biosensors, and humidity sensors.

双电层薄膜晶体管(EDLT)由于在栅介质和沟道的界面电容大和工作电压低被认为是可用于便携式传感器等领域的理想器件。然而，EDLT通常都采用有机材料，从而降低了器件的场效应迁移率和稳定性。针对这一问题，本项目拟采用Al2O3和SiO2质子导体膜作为栅介质，并采用铟锌氧(IZO)或铟锡氧(ITO)膜作为源极、漏极和沟道，制备新型工艺相对简单平面型无结(JL) EDLT。研究Al2O3和SiO2纳米颗粒膜的质子导电特性和EDL电容及其湿度、温度及其(H+、Li+等)表面修饰后对其的影响，揭示质子导体/沟道界面极化机理，建立氧化物质子导体极化机理的物理模型。期望获得工作电压低于1.5 V，电流开关比大于10^7，场效应迁移率大于40 cm^2/Vos的JL EDLT。对氧化物半导体沟道载流子的调制作用进行准确建模。本项目将为便携式化学、生物和湿度等传感器提供必要的实验依据和器件基础。

实现氧化物质子导体薄膜及其在低电压无结薄膜晶体管中的应用是几年来最为关注的课题之一。本项目采用Al2O3和SiO2质子导体膜作为栅介质，并采用铟锌氧(IZO)或铟锡氧(ITO)膜作为源极、漏极和沟道，制备新型工艺相对简单平面型无结(JL)双电层薄膜晶体管(EDLT)。揭示质子导体/沟道界面极化机理。.首先，采用等离子体增强化学气相沉积(PECVD)技术，通过系统调控工作气压、氧分压等制备条件，获得了Al2O3和SiO2质子导体膜，其反应残留和表面吸附的水或者羟基在静电场调控下具有大于1.0×10^-4 S/cm的质子导电率和大于1.0 μF/cm^2的双电层电容。采用ITO或IZO薄膜作为沟道层制备了以Al2O3和SiO2质子导体薄膜为栅介质的JL EDLT，其工作电压低于1.5 V，电流开关比大于1.0×10^7，场效应迁移率大于30 cm^2/V•s。.其次，系统研究不同浓度磷酸表面修饰后对SiO2质子导电特性和以此SiO2质子导体膜为栅介质的JL EDLT性能的影响。SiO2质子导体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SiO2质子导体膜质子电导率和双电层电容分别高达1.5×10^-4 S/cm和6.0 μF/cm^2以上。随磷酸浓度升高，JL EDLT工作电压降低，并且，电流开关比也增大。其中60%浓度磷酸处理后器件工作电压为1.2V，迁移率为20cm^2/V•s，电流开关比为4.0×10^6。.最后，建立具有普适性的氧化物质子导体/沟道界面形成大电容的极化机理模型，拓展到诸多电子绝缘/质子能够输运的纳米孔/纳米颗粒构筑绝缘栅介质材料中，例如海藻酸钠，壳聚糖，其他高k薄膜材料等，并且，研究以这些薄膜为栅介质的EDLT。.氧化物质子导体/沟道界面电容可以通过水平和垂直两种耦合方式，进一步简化器件制备工艺，例如无底栅器件结构，有望简化集成电路设计；基于氧化物质子导体的EDLT具有人脑神经突触行为，为类脑器件提供必要的实验依据和器件基础。