基于镓锡氧化物的薄膜晶体管的制备、电学特性与缺陷研究

Thin film transistors (TFTs) based on amorphous oxide semiconductor (AOS) exhibit high mobility and good flexibility. The cutting-edge research on the conductive mechanism and the defect states benefits profound physics and commercial applications. Extensive research has been paid to AOS based on indium and zinc, and suggests that the active properties of zinc can lead to instability; moreover, the indium is relatively scarce. Consequently, it is difficult to produce rather uniform, stable, and low-cost film. Therefore, in this project, we propose to use indium-free and zinc-free AOS, i.e., gallium-tin-oxide as the active layer material. The research mainly includes: (1) To fabricate films by vacuum sputtering and sol-gel method, respectively, and to characterize the microstructure, especially the ionic bonding; (2) To investigate the nature of the charge transport and the method to modulate; to reveal the mechanisms of mobile carrier generation and conductive path formation; and to model the electrical structure (including energy band, density of states, mobility, etc.); (3) To analyze how defect states are generated by oxygen vacancy or metal dangling bonds, how they affect the charge transport, and how they can be healed or passivated; (4) To graphical print arrays of TFTs for logical circuit applications. The proposed project aims to reveal the key of charge transport mechanism in gallium-tin-oxide and to develop reliable modulation of the microscopic electrical conductivity. The results are expected to explore the experimental and theoretical basis for the fundamental science of zinc-free and indium-free AOS as well as the potential in electric applications.

无定型氧化物半导体的薄膜晶体管，有迁移率高、可挠性好的优点，其导电机理和缺陷态的前沿研究，同时具有深刻物理和应用前景。已有大量对铟锌系氧化物半导体的研究，表明锌的活跃性质易带来不稳定因素，而铟又是比较稀缺的元素，故薄膜难以均匀、稳定，且制备成本高。因此，本项目拟研究用非铟锌系氧化物半导体，即镓锡氧化物作为有源层材料。主要研究内容包括：(1) 用真空溅射和溶胶凝胶法，分别制备薄膜并实现对微结构、离子价态的表征；(2) 研究电荷传输性质及其调控，揭示载流子产生和导电通道形成的机制，建立电学结构模型（能带、态密度、迁移率等）；(3) 分析氧空位或金属悬挂键造成缺陷态的形成机理、对导电性质的影响，并得到修复的机制和方法；(4) 获得用图形化印刷晶体管阵列的功能电路。本项目将揭示镓锡氧化物的关键电荷输运机制，获得调控导电性的微观机理和可靠方法，开拓非铟锌系氧化物半导体的基础研究和潜在应用。

本项目基本完成申请书中提出的内容。.在半导体薄膜方面，研究了镓锡氧基薄膜在氧化物薄膜晶体管中的工作机理，分析了阳离子元素（Al、Zr、Ga、Y）掺杂对半导体载流子浓度及迁移率的影响作用，同时探究了无机高介电常数介电层（Al2O3、ZrO2）对载流子传输的影响；从钝化缺陷出发，还探索了有机聚合物钝化层对晶体管性能的改善作用。.在晶体管工作机理方面，首先研究了不同材料组分对TFT器件各项性能参数的影响，然后建立了广义四探针测试法和广义范德堡法用于分析半导体层的本征性质和检验器件在制备过程中的一些非理想接触效应，成功解决了著名的“双斜率”现象和边缘电流效应带来的迁移率估计误差问题。.在制备工艺方面，开发了溶液图形化制备方法，并研发了具有低成本、快速大面积等优点的近场光刻技术，实现了亚微米尺度以下微结构的制备，并演示了近场光刻技术在周期性微结构异质结的晶体管的应用。同时研究了一种面向大面积电子电路的简单封装和钝化方法，可以大幅提升了氧化物晶体管的电流和表观迁移率。.以上研究获得的研究成果，已在相关领域的国际知名刊物 (SCI收录) 发表论文 11篇（均标注自然科学基金来源），申请1项发明专利，培养博士研究生2人、硕士研究生2人，加入电子或显示相关的企业。基本完成项目的目标。