【作者】 赵静；

【导师】 曾葆青；

【作者基本信息】 电子科技大学 ， 电子科学与技术， 2025， 博士

【摘要】 近年来,微纳技术的进步使场发射器件的尺寸减小、功耗降低,为适应更多小型化和低功耗的电子设备需求,提供了一个强有力的新平台。传统工艺下的场发射器件需要高真空、高压和高场强,使发射体在寿命,均匀性,稳定性,制造工艺等方面面临挑战,研究者们将传统场发射与现代微纳加工技术结合,开启了场发射应用领域的新大门。场发射阴极作为电子器件中的关键部件已在显示、微波、航天领域获得了广泛应用。随着碳基纳米材料兴起,基于碳纳米管(carbon nanotubes,CNTs)的冷阴极电子枪以其低功耗电子源、轻量化结构、极端环境适应性和快速开关响应等优点逐渐成为推进系统比如电动力绳系(Electrodynamic Tether,EDT)系统中的关键研究内容。进一步地,为了降低工作电压和功耗,通过材料纳米化(如碳纳米管、纳米线)与微纳加工精细化、阵列化,在微纳真空领域,催生出等离激元增强场发射、等离激元介导电子发射等新机制。场发射技术结合等离激元场增强效应的应用,推动场发射技术向非真空环境兼容、低功耗与片上集成方向演进。本文主要开展工作如下:1.EDT系统中裸系绳上的电流耦合至关重要,其与系统与电离层中电荷交换过程及冷阴极场发射电子特性密切相关。首先,构建平面单栅无聚焦冷阴极电子作为电子发射模型,研究其结构参数对冷阴极电子枪电子发射特性的影响;研究在真空或稳态均匀等离子体环境中场致电子发射特性,展现场发射阴极作为电动力绳系系统中电子发射装置的优势。其次,结合轨道运动限流(orbital-motion-limited(OML)current)理论分析导电绳通过电离层产生电流回路过程,并在稳态均匀等离子体环境中分析等离子体密度、系绳参数对电子捕获的影响。2.通过丝网印刷工业方法研究制备低成本、低开启场碳纳米管冷阴极电子枪,并研究基于CNTs冷阴极电子枪的电子发射特性。通过引入银浆过渡层,提高退火温度到800℃以提高阴极和基底结合力,该优化工艺提升单壁碳纳米管阴极的场发射性能。在400V阴-栅间电压下获得1.3mA阳极电流,开启场强降低至0.98V/μm,较500℃退火温度下(2.1V/μm)降低53%,且在全程测试中未出现烧栅或短路现象。进一步,为提高阴极寿命以及电子发射稳定性,研究表面改性对冷阴极场发射电流的影响,在80分钟连续测试中电流没有下降趋势,阳极电流仅变化1.6%,较涂敷前降低33.4%;栅极电流变化2%,较涂敷前降低41%,栅极截获率约为38%,证明其具有良好的电子发射稳定性。3.纳米沟道器件对进一步研究场发射在室温、大气环境和更低驱动电压下的电子发射特性不可或缺。再考虑等离激元增强光与物质相互作用,本研究针对具有等离激元场增强效应的周期性金属纳米沟道结构的光助场发射特性展开系统性探索。通过设计周期性的金属纳米沟道结构,实现了740nm激励光源与表面等离激元共振波长的匹配,论证了结构特征对光共振吸收和局域场分布的影响。为实现多级场增强,结合纳米尖端和等离激元局域场增强,设计含纳米尖端的周期性金属纳米沟道结构。随后评估加工容差对光照下含纳米尖端的周期性金属纳米沟道结构共振吸收峰的影响,验证了该结构对加工误差的强鲁棒性。在直流场发射模拟中,含纳米尖端的周期性金属纳米沟道结构表现出更优异的电子发射特性并研究尖端形貌对发射电流的影响。4.通过电子束曝光与紫外光刻等工艺制备了具有等离激元增强效应的含纳米尖端的周期性金属纳米沟道结构。真空以及室温、大气环境下场发射直流测试证明周期性金属纳米沟道结构在大气条件下依然拥有真空中电子发射特性。研究不同波长LED灯激励对场发射性能影响,实验测试结果表明该含纳米尖端的周期性金属纳米沟道结构对光具有选频特性。在小偏置电压(<5 V)下,当电压为4.7V时,在1W/cm~2量级、中心波长740nm的LED照明下,电流增加了25%,而偏离共振波长的光源则未引发明显电流变化。理论分析表明,该现象源于等离激元共振与几何场增强的协同效应,使含纳米尖端的周期性金属纳米沟道结构在LED灯激励、低偏压条件下即可实现电流增加。本文聚焦通过微纳技术制备的场发射电子器件在不同领域的应用研究,在理论建模、结构设计与实验测试三方面开展研究。首先,基于轨道运动限流理论设计电动力绳索(EDT)系统的电子发射模型,研究EDT系统中基于CNTs冷阴极电子枪的电子发射特性。其次,采用丝网印刷工艺优化碳纳米管阴极制备,进行提升退火温度、表面改性等方面研究,实现冷阴极电子枪场发射性能提升。最后,针对非真空环境应用需求,设计含纳米尖端的周期性金属纳米沟道结构,通过等高激元共振实现光-电场发射协同增强。构建等离激元增强金属纳米结构电子发射模型,并进行实验研究。本文有助于场发射技术向低功耗、轻量化、环境兼容性、与光子集成方向演进。更多还原

【Abstract】 In recent years,advancements in micro-nano technology have enabled the minia-turization and reduced power consumption of field-emission devices,providing a robust new platform to meet the growing demand for compact and low-power electronic sys-tems.Traditional field-emission devices,constrained by requirements for high vacuum,high voltage,and strong electric fields,face challenges in lifespan,uniformity,stability,and manufacturing processes.Researchers have integrated conventional field-emission technologies with modern micro-nano fabrication techniques,opening new frontiers in field-emission applications.As a critical component in electronic devices,field-emission cathodes have been widely adopted in displays,microwave systems,and aerospace appli-cations.With the rise of carbon-based nanomaterials,cold cathode electron guns based on carbon nanotubes(CNTs)with the feature of low-power electron sources,lightweightstructures,adaptability to extreme environments,and rapid switching responses have emerged as key research areas in propulsion systems,such as electrodynamic tether(EDT)systems.Furthermore,to reduce operating voltage and power consumption,the nanoscaling of materials(e.g.,carbon nanotubes,nanowires)combined with the refinement and arraying of micro/nano fabrication has given rise to new mechanisms within the micro/nano vac-uum domain,such as plasmon-enhanced field emission and plasmon-mediated electron emission.The application of field emission technology combined with plasmonic field enhancement effects is driving its evolution towards compatibility with non-vacuum en-vironments,low power consumption,and on-chip integration.The main work conducted in this paper is as follows:1.In the Electrodynamic Tether(EDT)system,the current coupling on bare tethers is critically important,as it is closely related to charge exchange processes between the sys-tem and the ionosphere,as well as the field emission electron characteristics of cold cath-odes.First,a planar single-grid,non-focusing cold-cathode electron gun is constructed to establish an electron emission model,investigating the influence of structural parame-ters on the electron emission characteristics of the cold cathode electron gun.The field-induced electron emission properties in vacuum or steady-state homogeneous plasma en-vironments are studied,providing crucial theoretical support for the design of space-based electron emission devices.Secondly,combining the Orbital-Motion-Limited(OML)cur-rent theory,the process of current circuit generation through ionospheric interaction by conductive tethers is analyzed.Additionally,the effects of plasma density and tether pa-rameters on electron collection are investigated under steady-state homogeneous plasma environments.2.Study on the preparation of low-cost,low turn-on field CNTs cold cathodes are studied through the screen-printing industrial method using carbon nanotubes paste,and electron emission characteristics are investigated from cold cathode electron guns based on CNTs.The adhesion between cathode and substrate was enhanced by introducing a silver paste transition layer and increasing the annealing temperature to 800℃.This optimized process significantly improved the field emission performance of screen-printed single-wall carbon nanotube cathodes,achieving 1.3mA anode current at 400V gate voltage with a reduced turn-on field strength of 0.98V/μm-representing a 53%reduction compared to 500℃ annealing condition(2.1 V/μm).There is no gate burning or short-circuiting occurred throughout testing.Furthermore,to enhance cathode lifespan and emission sta-bility,surface modification effects on cold cathode field emission current were investi-gated.During an 80-minute continuous test,the current showed no declining trend with only 1.6%variation in anode current,2%fluctuation in gate current,and approximately～38%gate interception rate,demonstrating excellent electron emission stability.3.Nanogap devices are indispensable for further investigation of field emission char-acteristics under room temperature,atmospheric conditions,and lower driving voltages.Considering plasmon-enhanced light-matter interactions,this study systematically explores the photo-assisted field emission properties of periodic metallic nanogap structures with plasmonic field enhancement effects.By designing periodic metallic nanogap structures,we achieved wavelength matching between a 740 nm excitation light source and sur-face plasmon resonance,while investigating the influence of structural features on optical resonance absorption and localized field distribution.We developed a periodic metallic nanogap structure integrated with nanotips and plasmonic localized field enhancement to realize multistage field enhancement.Subsequently,we evaluated the impact of fab-rication tolerances on the resonance absorption peaks of the nanotip-incorporated peri-odic metallic nanogap structures under illumination,demonstrating their strong robust-ness against processing errors.In DC field emission simulations,the nanotip-integrated periodic metallic nanogap structures exhibited superior electron emission characteristics,with additional investigations conducted on the influence of tip morphology on emission currents.4.Periodic metallic nanogap structures with nanotips and plasmonic enhancement ef-fects were fabricated through electron beam lithography and ultraviolet lithography pro-cesses.Field emission with the DC bias under both vacuum and ambient atmospheric conditions(room temperature,atmospheric environment)demonstrated that the periodic metallic nanogap structures maintained their electron emission characteristics in atmo-spheric conditions similar to those in vacuum.The study investigated the influence of different wavelength LED illuminations on field emission performance.Experimental results demonstrated that these nanotip-integrated periodic metallic nanogap structures exhibit wavelength-selective characteristics to light excitation.The ratio of the current increment under 740?nm illumination to the field electron emission current is about 25%when the voltage is 4.7?by LED with intensity on the order of 1W/cm~2,while light sources deviating from the resonant wavelength induced negligible current changes.Theoreti-cal analysis reveals that this phenomenon originates from the synergistic effects between plasmonic resonance and geometric field enhancement,enabling the nanotip-integrated periodic metallic nanogap structures to achieve current enhancement under LED illumi-nation with low bias voltages.This dissertation focuses on research advancements in field-emission electronic de-vices fabricated through micro-nano technology across various domains,achieving signif-icant progress in theoretical modeling,structural design,and experimental testing.First,an electron emission model for the Electrodynamic Tether(EDT)system is designed based on the Orbital-Motion-Limited(OML)theory,investigating the electron emission char-acteristics of carbon nanotube(CNT)-based cold cathode electron guns in EDT systems.This provides theoretical support for EDT system design.Second,the screen-printing pro-cess is optimized for CNT cathode fabrication,with studies on elevating annealing tem-peratures and surface modification,leading to breakthroughs in the field emission perfor-mance of cold cathode electron guns.Finally,to address non-vacuum environmental ap-plications,a periodic metallic nanochannel structure with nanotips is designed,achieving synergistic enhancement of photo-electric field emission through plasmonic resonance.A plasmon-enhanced metallic nanostructure electron emission model is constructed and experimentally validated.This work facilitates the evolution of field-emission technol-ogy toward low power consumption,lightweight design,environmental compatibility,and photonic integration.更多还原