催化辅助化学气相沉积工艺制备HfC纳米线及其场发射机理探索

Obtaining the pure and large scale HfC nanowires with controllable growth orientation and microstructure is of great importance for the application of HfC nanowires as field emission. HfC nanowires were prepared by catalyst-activated vacuum chemical vapor deposition. The controllable growth HfC nanowires on a large scale were obtained with changing the catalyzer, carbon resource and deposition processing parameter. The influence of the preparation processing parameter on the microstructure and field emission properties were investigated. The relationship among the preparation processing parameter, microstructure and field emission properties were established. The growth mechanism of HfC nanowires with different microstructure was analysized. The controlling method and processing rule of the microstructure, growth orientation and array interval was studied. The relationship between the current density and the pressure and the field emission time was investigated, from which some important filed emission properties can be obtained. The influence of the vacuum degree and the distance between the cathode and anode on the field emission properties was investigated; the relationship between the field emission condition and field emission properties was established. The field emission mechanism of HfC nanowires was discussed. The above research can lay a theoretical foundation for the application of HfC nanowires prepared by chemical vapor deposition as the field emission cathode.

宏量制备出纯度高、生长方向及结构形貌可控的HfC纳米线对其在场发射领域的应用具有十分重要的意义。本项目提出采用催化辅助低压化学气相沉积工艺，通过改变催化剂、碳源、沉积工艺等参数来制备大量可控生长的HfC纳米线。研究不同制备工艺参数对所制备HfC纳米线的微观结构及场发射性能的影响规律，建立制备工艺参数-微观结构-场发射性能之间的关系；阐明不同微观结构HfC纳米线的生长机理；重点研究HfC纳米线微观结构、生长方向及阵列间距的调控方法及工艺规律；探索HfC纳米线场发射电流密度随加载电压和场发射运行时间的变化规律，获得其场发射性能的几个关键性能指标；分析场发射真空室真空度和阴阳极间距对HfC纳米线场发射性能的影响规律，建立HfC纳米线的场发射运行条件与场发射性能的关系，揭示HfC纳米线的场发射机理，为CVD-HfC纳米线作为场致发射阴极材料的应用奠定理论基础。

宏量制备出纯度高、生长方向及结构形貌可控的HfC纳米线对其在场发射领域的应用具有十分重要的意义。本项目提出采用催化辅助低压化学气相沉积工艺，通过改变沉积工艺参数制备出大量可控生长的HfC纳米线。获得了不同制备工艺参数对所制备HfC纳米线的微观结构及场发射性能的影响规律，建立了制备工艺参数-微观结构之间的关系；阐明了不同微观结构HfC纳米线的生长机理；获得了HfC纳米线场发射电流密度随加载电压和场发射运行时间的变化规律，所制备的HfC纳米线具有很好的场发射性能，开启电场为1.6–1.7 V μm-1。场增强因子不低于4869，2 h内的电流密度围绕20 μA cm-2的中心电流密度最大波动为~15%。建立了HfC纳米线的场发射运行条件与场发射性能的关系，揭示HfC纳米线的场发射机理，为CVD-HfC纳米线作为场致发射阴极材料的应用奠定理论基础。