底栅结构InGaZnO薄膜晶体管的背沟道表面修饰、电荷转移及新耦合电学特性研究

As one of the hot topics, thin film transistors coupled with brand new functionalities are emerging devices, which have gained ever-increasing attention because they would allow to combine new functionalities into the conventional electronic switch component to realize multi-function integrated devices. This project will focus on the well-planned research objectives, highlighted as the bottom gate InGaZnO thin film transistor and its foreign matter decorated back channel, to study the gate-tunable electrical characteristics triggered by the variations of the carrier concentration in the channel due to the external light illumination excited directional charge transfer between NiO micro/nano structures and back channel layer. The approving project implementation is based on revealing the direction of the charge transfer responded to the light stimuli, uncovering the variation trends of the electrical characteristics, including field-effect mobility, threshold voltage, on-off current ratio and subthreshold swing, and so on, illuminating the effect of the Debye screening length, the channel bulk trap density, and the interfacial trap density on the electrical performance, and eventually building a physical model to describe the working mechanism of the device with the help of the band diagram. The aim of this project lies in establishing the coupling relationship between the electrical and optical signals, reflecting the innovation for the device structure and the creative thinking on exploring novel devices as well. It is expected that the successful implementation of this project would pave the way for the development of novel function integrated electronics, which has great significance whether for the scientific research or for the practical applications.

引入新耦合功能的薄膜晶体管已成为国际研究热点，其引人之处在于为传统电子开关元器件赋予新功能，实现多功能集成。本项目以底栅结构InGaZnO薄膜晶体管为研究对象，利用p型NiO微纳结构修饰背沟道表面，在外励光信号作用下，诱发的定向电荷转移使得沟道内载流子浓度发生变化，从而反映在栅压可调控的电学输出特性上。研究暗光和光照条件对NiO和背沟道之间的电荷转移方向的影响，揭示栅压有效调控下的晶体管场效应迁移率、阈值电压、开关比及亚阈值摆幅的变化趋势，阐明半导体德拜屏蔽长度、沟道体电子陷阱密度、沟道/介电界面处电子陷阱密度的变化规律，结合器件的半导体能带结构，建立器件工作的物理模型。本项目通过在背沟道上构筑修饰物诱发光信号和电信号之间的关联耦合，体现了器件结构设计创新性和器件新功能开发的创新思路。通过本项目的实施，有望推动新功能集成的电子学器件的研发进程，具有重要的科学研究和现实应用意义。

引入新耦合功能的薄膜晶体管已成为国际研究热点，其引人之处在于为传统电子开关元器件赋予新功能，实现多功能集成。本项目以底栅结构InGaZnO薄膜晶体管为研究对象，通过在其背沟道表面依次修饰超薄SnOx层和p型透明PEDOT:PSS有机层，结合两端PN结和三端薄膜晶体管的结构优势，使得 IGZO TFT在 pn结作用下的光电响应和光敏性均得到了显著的提高，可应用于可见盲紫外探测器和光敏神经突触器件。.首先，通过调控SnOx修饰层厚度，实现了IGZO晶体管阈值电压的宽范围可调（15.2 V～-9.0 V），工作模式可在增强型和耗尽型之间转变；联接增强型和耗尽型薄膜晶体管成功构筑了NMOS反相器，其增益达56.4，优于文献报道的同类型反相器。.其次，通过在耗尽型的SnOx/IGZO薄膜晶体管背沟道表面继续修饰p型PEDOT:PSS薄膜，充分利用了两端和三端器件的结构优势，使得 IGZO TFT在 pn结作用下的光电响应和光敏性均得到了显著的提高。该新型器件的光电性能明显优于传统的两端结构探测器，在320 nm紫外光作用下器件的光响应度可达984 A/W，光敏性（光暗电流比）约为106，紫外可见光的抑制比为3.5×107，最大外部量子效率约为107，且在320 nm下的探测率约为3.3×1014 Jones，这些关键参量均比未修饰晶体管的高出至少两个量级。而且通过电压调控能够进一步地降低探测器的功耗（VDS = 0.1 V，VG = 0 V），在光照条件和暗态条件下的功耗分别约为10 nW和0.2 pW。结合能带结构示意图阐明了薄膜晶体管三端器件与pn结两端器件相耦合情况下光电导的形成与调控机理。.最后，构建了高灵敏、低功耗模拟视觉神经突触电子器件，器件工作在可见光和紫外光区，对信号强度可低至1 µW/cm2的蓝色光脉冲具有响应性，具有长程、短程可塑性，并具有选择性记忆和遗忘功能，单个器件电学功耗小于10 pW，可实现光输入、电擦除功能。