【摘要】 Spindt型场发射阴极,在初期老炼过程中容易失效,其表现为发射尖锥和栅极间短路、漏电,或是真空电弧损伤。引起Spindt阴极失效的一个主要原因,分析认为是存在于发射尖锥表面、栅极边缘以及承载尖锥的二氧化硅空腔中的金属颗粒附着。这些金属颗粒,产生于双向沉积制作发射尖锥过程中,它们在牺牲层剥离时脱落,并且没有在随后的纯水清洗过程中得到有效去除。这些金属颗粒的存在,即便没有导致初期阴极失效,也可能成为阴极大电流应用,如微波真空功率器件应用的潜在障碍。研究中提出了在常规清洗工艺中引入超声波清洗和兆声波清洗,初步试验研究表明,振动频率28 k Hz的超声波清洗,容易造成阴极损伤,并且对微小颗粒的去除效果不好,而频率1 MHz的兆声波清洗,则可近似无损地将阴极失效率大幅降低。更多还原

【Abstract】 The mechanisms responsible for the failures of Spindt type field emission cathodes in its initial seasoning stage,including but not limited to the short circuit,current leakage,and arc discharge induced damages of the emission cones and gate layers,were investigated with scanning electron microscopy. The results show that the molybdenum particles,deposited and strongly adsorbed on the emitter cones,gate edges and Si O2 cavities in fabrication of Spindt cathode,have a major impact on the failures. Moreover,contamination of metal particles could be potential hazards when Spindt cathode is used in high power microwave vacuum electronic devices. Since conventional de-ionized( DI) water rinsing failed to completely remove the strongly adsorbed metal particles,ultrasonic cleaning was performed. Ultrasonic cleaned at 28 k Hz,contamination of submicron particles and serious damages were still observed; whereas at 1 MHz,the Mo-particles,including the submicron ones,were almost non-destructively removed.更多还原