透明氧化物半导体及其溶液法制备薄膜晶体管

透明氧化物电子材料是当今最重要的电子材料之一,其本质是一类具有高迁移率的宽带隙半导体。通过调节其组分和结构,可以大范围调节其载流子浓度,从而使其表现为半导体或者导体性质。因此,透明氧化物电子材料可用于多种器件,特别是作为半导体沟道和透明导电电极。透明导电氧化物更早成为了研究热点,并已在商业化应用中广泛使用,透明氧化物作为新一代半导体也被广泛研究,现在透明氧化物半导体薄膜晶体管已经可以实用化。在较低的温度和大气环境中,通过溶液法制备的透明氧化物,表现出了较好的电子特性,因此成为了印刷电子中重要的领域。简要地介绍了透明导电氧化物和透明氧化物半导体晶体管的发展历程,并概述了溶液法制备透明氧化物晶体管方面所做的研究及取得的最新进展。并指出,现今采用的溶液法制备工艺所存在的问题,特别是工艺温度偏高,应进一步深入研究,使在低温工艺下制备高性能透明氧化物晶体管工艺走向成熟,才能进入工业化生产。     

溶胶-凝胶法制备透明氧化物薄膜晶体管的研究进展

透明非晶氧化物薄膜晶体管(TAOS-TFT)相对于硅基TFT具有均一性好、迁移率高、兼容低温柔性基板等优点,能够广泛用于平板有源显示领域特别是有源矩阵有机发光二极管显示(AMOLED)的驱动背板。溶胶-凝胶法制备薄膜晶体管不需要高真空的环境,成本低、工艺简单,化合物成分易于控制,能够均匀定量地实现分子水平的掺杂,满足新技术研发的需求,近年来引起了广泛关注,研究主要集中在寻找合适有源层和绝缘层材料、研究薄膜成分、制备工艺对器件性能的影响,并获得与传统真空工艺可比拟的器件性能。针对柔性显示器件成为未来显示发展的主流技术之一,全溶液法制备以及基于柔性基板制备TFT也取得了较好的进展,为未来显示行业提供了可靠的低成本发展方向。但所制备的TFT器件仍然存在制备温度相对较高,偏压稳定性相对较差的问题。总结了该领域内目前研究热点及取得的进展。     

铟镓锌氧化物薄膜晶体管制备及性能研究

为了实现高质量刻蚀阻挡型InGaZnO薄膜晶体管(IGZOTFT)器件,研究了IGZO TFT关键制备工艺,其中重点探讨了IGZO成膜氧分压、退火工艺、IGZO成膜均一性对于IGZO TFT电学特性的影响。通过优化成膜和退火工艺在G6玻璃基板上制作的IGZOTFT器件,阈值电压0.72 V,亚阈值摆幅0.2 V/dec,迁移率9.57 cm~2/V·s,Ion/Ioff10~8,IGZO TFT大基板阈值电压均一性最大偏差小于2 V。最后进行了IGZO TFT长期稳定性测试以及正负偏压应力测试,结果表明IGZO TFT器件经过长时间空气暴露会导致特性劣化,负向偏压应力劣化较为明显。所制备的刻蚀阻挡型IGZO TFT器件可以满足高质量液晶显示的要求。     

非晶ZnTiSnO薄膜的溶液燃烧法制备与TFT器件性能

本文采用溶液燃烧法,在较低温度下成功制备出非晶ZnTiSnO(ZTTO)薄膜,用作沟道层制备薄膜晶体管(TFT)。研究了Ti掺入对薄膜的结构、光学性能、元素化学态以及对TFT器件电学性能影响。研究结果表明,所制得的ZTTO薄膜均为非晶结构,可见光透过率大于84%;适量Ti的掺入可作为载流子抑制剂有效降低薄膜中的氧空位缺陷浓度,从而提升TFT器件性能。当Zn/Ti摩尔百分比为30/1时,ZTTO TFT性能良好,开关比可达3.54×10~5。     

ZnO薄膜晶体管的制备和特性研究

通过原子层沉积法制作底栅型ZnO-TFT,并从衬底温度,氧化锌层厚度以及退火温度几个方面,分析对器件输出特性,转移特性和开关比的影响。     

以ZnO为沟道层的薄膜晶体管制备研究

采用光刻剥离工艺和射频磁控溅射法分别在(100)硅片和ITO玻璃衬底上制备了以氧化锌为沟道层的底栅式薄膜晶体管(ZnO-TFT).用X射线衍射仪、原子力显微镜对生长在绝缘层上的ZnO薄膜进行了表征.在硅衬底ZnO-TFT中,热氧化生长的二氧化硅薄膜作为绝缘层,金属铝用作源漏电极,该器件工作在N沟道增强模式,其阈值电压为8V,电流开关比为5×103,电子的场迁移率达到0.61cm2/(V·s).在以ITO玻璃为衬底的透明ZnO-TFT中,分别采用了SiO2、Al2O3、SiNx、PbTiO3薄膜作为绝缘层,实验表明生长在不同绝缘层上的ZnO薄膜都有很高的c轴择优取向,透明ZnO-TFT在可见光波段的平均透过率达到85%.     

非晶铟锌钨氧化物薄膜晶体管的电学性能和稳定性研究

采用射频磁控溅射法制备了非晶铟锌钨氧化物(a-IZWO)薄膜和以此半导体薄膜为沟道层的薄膜晶体管。研究了沟道宽长比和退火时间对器件电学性能的影响。结果表明,沟道宽长比为400μm:400μm的器件经过120min 200℃空气退火后其电学性能达到最佳,场效应迁移率达到7.29 cm²/Vs,阈值电压为-2.86 V,电流开关比超过10⁷,亚阈值摆幅低至0.13 V/decade。偏压稳定性测试结果证实了器件的偏压稳定性主要受到沟道层缺陷、背沟道表面氧离子和H₂O⁺离子吸附等因素的影响。随着器件沟道宽长比不断增大,退火时间不断延长,器件受到这些因素的影响变小,稳定性越来越好。     

热处理气氛对溶胶-凝胶法制备a-InGaZnO TFT器件的影响

采用溶胶-凝胶法制备了非晶铟镓锌氧化物(a-IGZO)薄膜,通过热重-差热示差技术分析了a-IGZO形成机理,并研究了热处理对a-IGZO薄膜的结构和光电性能影响。并用于薄膜晶体管(TFT)的有源层,制备的a-IGZO TFT,其具有明显的转移特性,其关态电流为10-11 A,退火能够改善a-IGZO TFT器件性能,器件的开关比提高了两个数量级。     

非晶铟锌钨氧化物薄膜晶体管的电学性能和稳定性研究北大核心CSCD

采用射频磁控溅射法制备了非晶铟锌钨氧化物(a-IZWO)薄膜和以此半导体薄膜为沟道层的薄膜晶体管。研究了沟道宽长比和退火时间对器件电学性能的影响。结果表明,沟道宽长比为400μm:400μm的器件经过120min200℃空气退火后其电学性能达到最佳,场效应迁移率达到7.29 cm^2/Vs,阈值电压为-2.86 V,电流开关比超过10~7,亚阈值摆幅低至0.13 V/decade。偏压稳定性测试结果证实了器件的偏压稳定性主要受到沟道层缺陷、背沟道表面氧离子和H_2O^+离子吸附等因素的影响。随着器件沟道宽长比不断增大,退火时间不断延长,器件受到这些因素的影响变小,稳定性越来越好。     

溶胶凝胶法制备的Mn系氧化物热敏薄膜的尺寸效应

本文阐述了用溶胶凝胶法制备ＣｏＭｎＣｕＯ等热敏薄膜的方法，研究了它们的电学性质。结果表明，薄膜的Ｒ－Ｔ特性基本符合Ｒ＝Ｒｏｅｘｐ（Ｂ／Ｔ）关系。在本文样品厚度的范围内，厚度对电阻率（ｐｔ）和材料常数（Ｂ）有较大的影响。利用扩展电阻仪分析了电阻率随深度的变化，用俄歇电子能谱分析了组分随深度的变化，在此基础上对尺寸效应作出了相应的解释。     

有机薄膜晶体管（OTFT）的研究进展

近几年来，有机薄膜晶体管（OTFT）有了飞跃的发展，可望在某些方面与无机晶体管电子元件进行竞争。本文综述了有机薄膜晶体管的优势、材料类型、器件制作方法的最新进展，以及目前需要解决的问题。     

Synergistic Improvement of Long-Term Plasticity in Photonic Synapses Using Ferroelectric Polarization in Hafnia-Based Oxide-Semiconductor Transistors

A number of synapse devices have been intensively studied for the neuromorphic system which is the next-generation energy-efficient computing method. Among these various types of synapse devices, photonic synapse devices recently attracted significant attention. In particular, the photonic synapse devices using persistent photoconductivity (PPC) phenomena in oxide semiconductors are receiving much attention due to the similarity between relaxation characteristics of PPC phenomena and Ca²⁺ dynamics of biological synapses. However, these devices have limitations in its controllability of the relaxation characteristics of PPC behaviors. To utilize the oxide semiconductor as photonic synapse devices, relaxation behavior needs to be accurately controlled. In this study, a photonic synapse device with controlled relaxation characteristics by using an oxide semiconductor and a ferroelectric layer is demonstrated. This device exploits the PPC characteristics to demonstrate synaptic functions including short-term plasticity, paired-pulse facilitation (PPF), and long-term plasticity (LTP). The relaxation properties are controlled by the polarization of the ferroelectric layer, and this polarization is used to control the amount by which the conductance levels increase during PPF operation and to enhance LTP characteristics. This study provides an important step toward the development of photonic synapses with tunable synaptic functions.     

Thin‐Film Transistors

Thin‐film transistors (TFTs) matured later than silicon integrated circuits, but in the past 15 years the technology has grown into a huge industry based on display applications, with amorphous and polycrystalline silicon as the incumbent technology. Recently, an intense search has developed for new materials and new fabrication techniques that can improve the performance, lower manufacturing cost, and enable new functionality. There are now many new options – organic semiconductor (OSCs), metal oxides, nanowires, printing technology as well as thin‐film silicon materials with new properties. All of the new materials have something to offer but none is entirely without technical problems.     

Meniscus-Guided Deposition of Organic Semiconductor Thin Films: Materials,Mechanism, and Application in Organic Field-Effect Transistors

Solution-processable organic semiconductors are one of the promising materials for the next generation of organic electronic products, which call for high-performance materials and mature processing technologies. Among many solution processing methods, meniscus-guided coating (MGC) techniques have the advantages of large-area, low-cost, adjustable film aggregation, and good compatibility with the roll-to-roll process, showing good research results in the preparation of high-performance organic field-effect transistors. In this review, the types of MGC techniques are first listed and the relevant mechanisms (wetting mechanism, fluid mechanism, and deposition mechanism) are introduced. The MGC processes are focused and the effect of the key coating parameters on the thin film morphology and performance with examples is illustrated. Then, the performance of transistors based on small molecule semiconductors and polymer semiconductor thin films prepared by various MGC techniques is summarized. In the third section, various recent thin film morphology control strategies combined with the MGCs are introduced. Finally, the advanced progress of large-area transistor arrays and the challenges for roll-to-roll processes are presented using MGCs. Nowadays, the application of MGCs is still in the exploration stage, its mechanism is still unclear, and the precise control of film deposition still needs experience accumulation.     

软溶胶-凝胶法制备LiCoO2薄膜电极

采用软溶胶-凝胶技术在金属Ni基体上一步合成LiCoO₂薄膜电极.其合成条件是:含钴离子和锂离子的溶液、反应温度100℃、反应压力0.1MPa、电流密度0～10mA/cm²、反应时间20h.XRD、XPS、SEM、循环伏安和恒电流充、放电等测试表明:薄膜电极LiCoO₂晶体为R3m型结构;薄膜具有(101)方向的择优取向,其大小均匀、直径约为0.3μm的晶粒层状生长,层与层之间结合较紧密且有较多微孔;薄膜电极表现为多孔电极,具有良好的电性能.软溶胶-凝胶法制备薄膜电极,工艺流程短、能耗低,具有很大的发展潜力.     

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n‐ and p‐type oxide based thin‐film transistors (TFT) is reviewed, with special emphasis on solution‐processed and p‐type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n‐type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution‐processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p‐type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n‐ and p‐type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n‐ and p‐type oxide transistors as well as the fabrication of CMOS devices with and on paper.     

软溶胶-凝胶法制备LiCoO2薄膜电极

采用软溶胶-凝胶技术在金属Ni基体一步合成LiCoO2薄膜电极。其合成条件是：含钴离子和锂离子的溶液、反应温度100℃、反应压力0.1MPa、电流密度0-10mA/cm^2、反应时间20h。XRD、XPS、SEM、循环伏安和恒电流充、放电等测试表明：薄膜电极LiCoO2晶体为R3^-m型结构；薄膜具有（101）方向的择优取向，其大小均匀、直径约为0.3μm的晶粒层状生长，层与层之间结合较紧密且有较多微孔；薄膜电极表现为多孔电极，具有良好的电性能。软溶胶-凝胶制备薄膜电极，工艺流程短、能耗低，具有很大的发展潜力。