铟锌氧化物薄膜晶体管(IZO TFT)因其载流子迁移率高、制备工艺温度低，可以应用于大尺寸和柔性电子器件等优点而引起广泛关注。目前学术界对于IZO TFT的研究，主要集中在如何实现高性能的显示面板的开关和驱动晶体管，但对于IZO TFT的光电特性的研究成果比较少。IZO薄膜的禁带宽度在2.9eV左右，属于宽禁带半导体材料。在长波可见光范围内，对光的透过率高达80%以上，但是在短波可见光和近紫外波段，IZO薄膜对光有较强的吸收特性。因此，IZO TFT有望成为一种良好的光电感应器件。本文主要研究了IZO薄膜和IZO TFT的光电特性，主要内容包括：首先研究了不同工艺条件下磁控溅射制备的IZO薄膜的光电特性。以溅射功率、氩氧比和气压为变量，采用磁控溅射的方法制备了不同条件下的IZO薄膜，并对薄膜的光电特性进行了测试、分析和比较。结果显示：薄膜溅射功率为100W时，薄膜电阻率达到最低，载流子浓度达到最高；当氩氧比为48：2和工作气压为0.4Pa时，薄膜迁移率达到最高。不同工艺条件下，制备出的薄膜均具有良好的可见光透过率（80%以上）。接着以IGZO TFT为例，介绍了器件制备的流程，并研究了源漏电极溅射功率对器件电学特性的影响。实验结果显示：随着源漏电极溅射功率的增加，有源层IGZO薄膜的表明粗糙度变差，器件电学性能退化。然后研究了氩氧比和有源层厚度对器件IZO TFT电学特性的影响。结果显示：随着溅射氧分压增加，器件的阈值电压正向移动，绝对值减小，但过高的氧分压会使得亚阈值摆幅变差；随着器件有源层厚度的增加，器件饱和迁移率降低，亚阈值摆幅变小，但过厚的有源层会导致载流子难以全部耗尽，亚阈值摆幅退化。综合以上规律，氩氧比为25/25，有源层厚度为100nm时，器件的电学特性最为理想。最后研究了溅射氧分压、有源层厚度和光功率对器件光电探测性能的影响。结果显示：IZO TFT的光响应度随着波长的减小而增加，随着氧分压的增大而减小，随有源层厚度的增加而增加。光电流随着光功率的增加而变大。
Indium-zinc oxide thin film transistors (IZO TFT) have attracted a great concern owing to its high carrier mobility, low temperature process and high transmittance at the visible-light, which can be applied to flexible and transparent electronics. At present, the research on IZO TFT mainly focuses on how to realize the switching and driving transistors of high-performance display panel. However, there are few researches on the photoelectric properties of IZO TFTs. The IZO films are broad band gap materials with a band gap around 2.9eV. The IZO films have a high transmittance over 80% in the visible light but still have sensitivity under near-UV light illumination. Therefore, IZO TFT is expected to become a good photoelectric sensor. This paper mainly studies the photoelectric performance of IZO film and IZO TFT. The main contents include:First, the photoelectric properties of IZO thin films prepared by magnetron sputtering under different process conditions were studied. The IZO films under different conditions were prepared by magnetron sputtering with sputtering power, argon oxygen ratio and air pressure as the variables. The photoelectric properties of the films were tested, analyzed and compared. The results show that when the sputtering power of the film is 100W, the resistivity of the film reaches the lowest, and the carrier concentration reaches the maximum. When the Ar / O2 ratio is 48: 2 and the working pressure is 0.4Pa, the film mobility is the highest. Under different process conditions, the prepared films have good visible light transmittance (more than 80%).Then IGZO TFT is taken as an example to introduce the process of device preparation and to study the influence of sputtering power of source and drain electrodes on the electrical characteristics of the device. The experimental results show that with the increase of the sputtering power of the source and drain electrodes, the roughness of the active layer of IGZO thin film deteriorates and the electrical properties of the device deteriorate.Then the influence of the ratio of argon to oxygen and the thickness of the active layer on the electrical characteristics of IZO TFT devices was investigated. The experimental results show that the threshold voltage of the device moves forward with the increase of the oxygen partial pressure, but the absolute value decreases. However, the excess oxygen partial pressure causes the subthreshold swing to deteriorate. With the increase of the active layer thickness, the device saturation mobility decreases, the subthreshold swing becomes smaller, but when the active layer becomes too thick，the carriers is fully depleted, which causes the subthreshold swing degradation. Combined with the above law, when the ratio of argon to oxygen is 25/25, the active layer thickness of 100nm, the electrical properties of the device is the most ideal.Finally, the effects of oxygen partial pressure, thickness of active layer and optical power on photodetection performance of the devices were studied. The results show that the photo responsivity of IZO TFT increases with decreasing wavelength, decreases with the increase of oxygen partial pressure, and increases with the increase of active layer thickness. The photocurrent becomes larger as the optical power increases.
