高迁移率MOCVD微晶氧化铟薄膜晶体管及可靠性研究

So far, the mobility of a-IGZO TFTs have stably achieved higher than 10cm2/Vs, but it is still unable to compare with low temperature poly-Silicon TFTs (50-100cm2/Vs). Moreover, the mobility of a-IGZO TFTs is insufficient to match any high frame displays such as high performance AMOLEDs or system on panel (SoP) applications. In2O3 with special electronic structure is expected to obtain high mobility. In our previous work, metal organic chemical vapor deposition (MOCVD) grown In2O3 was used as channel layer to fabricate high field-effect mobility TFTs. Oxygen microwave plasma treatment was applied to the In2O3 channel layer to reduce the background carrier density. The field effect mobility of the In2O3 TFTs was estimated as high as 243cm2/Vs, which is regarded as the highest u FE among.that of the oxide semiconductor TFTs reported. Based on the previous research achievements, in this project, we will comprehensively overcome the key scientific issues of microcrystalline In2O3 TFTs that poor reliability and stability. MOCVD will be employed to grow microcrystalline In2O3 channel layer owing to its advantages over physical processes such as high crystal quality and controllable stoichiometry. Through adjusting the MOCVD deposition parameters, we will reduce the defects of microcrystalline In2O3. In addition, the double gated TFT structure will be used in microcrystalline In2O3 TFTs. Combined with analysis of electron transport mechanism and stability mechanism, this project aims to achieve microcrystalline In2O3 TFTs with high mobility and high stability for potentially applications in the next-generation transparent integrated circuit and SoP.

目前，非晶铟镓锌氧化物薄膜晶体管（a-IGZO-TFT）的迁移率通常在20cm2/Vs以下，面对透明电路的发展需求，开发更高迁移率的氧化物薄膜晶体管迫在眉睫。氧化铟具有独特的电子结构，其电子迁移率有望优于其他氧化物半导体。在我们前期的研究工作中，初步探索了MOCVD微晶氧化铟薄膜晶体管，实现了超过200cm2/Vs的场效应迁移率。本项目，将以前期高迁移率氧化铟薄膜晶体管的研究成果为基础，利用MOCVD在薄膜材料微结构控制方面的优势，从材料缺陷控制和薄膜晶体管结构设计两方面入手展开系统研究。结合电输运机制解析、器件模型建立与稳定性机制解析，攻克微晶氧化铟基薄膜晶体管重复性和稳定性差等关键科学问题，实现高迁移率、稳定的氧化物薄膜晶体管，为透明集成电路等的发展提供实验和理论指导。

本项目针对OLED等高清晰显示产业、未来的System on Pannel（SoP）系统以及透明集成电路、生物传感等领域对高迁移率、高稳定性薄膜晶体管（TFT）的迫切需求，从微晶氧化铟基有源层材料的本质出发，采用MOCVD、溅射、可印刷溶液旋涂等不同方法制备了氧化铟基薄膜，探索材料生长热动力学环境、动力学过程与缺陷、晶体管稳定性之间的相关性，攻克有源层缺陷工程、界面工程等关键科学问题，构建高迁移率、高稳定性的微晶氧化铟基薄膜晶体管（TFT），并研究其新型应用。项目研究了氧化物半导体/栅介质层的界面态陷阱以及氧化物半导体体内陷阱的提取方法以及对器件稳定性的影响；研究了氧化铟基有源层和绝缘栅之间的异质集成与界面控制对TFT性能的影响，制备的全溶液法AlOx栅介质层InOx薄膜晶体管，获得了低操作电压和高表观迁移率，并利用双电层和赝电容机制分析了其电传输机制，实现了基于双电层的氧化铟薄膜晶体管型类脑神经突触器件。研究了InOx/AlInO叠层异质有源层薄膜晶体管特性，界面层形成了类似二维电子气的电子积累效应，获得了高迁移率，同时高铝组分的背沟道增加了晶体管的稳定性。项目利用MOCVD氧化铟基薄膜晶体管高耐腐蚀性的特性，开发了电解质栅型传感器件，成功实现了基于电解质栅的氧化铟薄膜晶体管（TFT）紫外探测器，紫外光响应度高达~5300A/W，紫外/可见光拒绝比为105，工作电压可低于1V，响应时间和衰减时间分别为0.3s和0.2s；开发的氧化铟基电解质栅型pH传感特性，其pH传感表现出了超高的pH灵敏度>75mV/pH。通过集成固态栅电极，氧化铟基电解质栅型生物传感器，其探测生物素的灵敏度高达约为200nA/dec.