Abstract: This paper reports on methods and examples of in-situ field emission measurements of individual one-dimensional nanostructures based on scanning electron microscope (SEM) and nanoprobe techniques. In the experimental setup, tungsten (W) tips and nanostructures acted as electron-receivers and emitters, respectively, based on which systematic studies of individual MWCNTs and ZnO nanowires were realized. By combining real-time imaging, nanoprobe technique for precise nanomanipulation and electric measurement, and light input, experiments were performed to study the influences of the receiver-emitter distance, morphology variation, adsorbed gas molecules, and laser irradiation. Results demonstrate that when D << 3L (L is the length of nanostructures), the turn-on fields and threshold fields increase with the decreasing D, indicating degraded field emission property. Besides, the increased curvature radius of nanostructures results in reduced field enhancement factor and field emission property. In addition, desorption of oxygen molecules and laser radiation improve the field emission properties of nanostructures.

Key words: scanning electron microscope, one-dimensional nanostructures, field emission property

摘要： 基于扫描电子显微镜和纳米探针技术, 展示了一维纳米材料原位场发射的测量方法和实例。实验以钨针尖为接收极, 纳米材料为发射极,通过结合扫描电子显微镜的实时成像功能,纳米探针的精确操纵及电学测量技术以及激光辐照功能, 系统研究了极间距离 D 、形貌变化、吸附气体和激光注入对单根多壁碳纳米管和氧化锌纳米线场发射性能的影响。结果表明,当 D 远小于纳米材料长度 L 的 3 倍时, D 越小, 开启场强和阈值场强越大, 场发射性能越弱。此外,纳米线尖端曲率半径越大, 场增强因子越小,场发射性能越弱。研究还发现 O2 的脱附和激光辐照有助于纳米材料场发射性能的提高。

关键词: 扫描电子显微镜, 一维纳米材料, 场发射性能