摘要
为了研究镧钼阴极表面发射机制,利用新型阴极研究装置研究阴极发射性能与表面元素La,O比例的关系,发现表面层中La/O比例越高,阴极的发射性能越好。在实验基础上提出了金属La超微粒子埋藏于La2O3晶体中的热阴极表面发射模型,模型认为活性层中的超额镧以镧超微粒子形式存在,La超微粒子中的电子在热激发下越过肖特基势垒进入La2O3晶体的导带进而克服表面电子亲和势逸出到真空,提供了电子发射的丰富源泉。由于肖特基势垒远小于La2O3的禁带宽度,并且超微粒子可以使耗尽层厚度变薄,极大降低了电子发射到真空的阈值。
To study the surface emission mechanism of La2O3-Mo cathode, we investigated the relation between cathode surface atomic La/O ratio and cathode emission property by a new set of cathode research instrument. It was found that the cathode emission properties were affected intensively by the surface atomic La/O ratio, the higher the La/O ratio, the better the emission property. According to the experiment results, we proposed the following cathode surface emission model in which La ultra-fine particles buried in the insulator （ La2O3 ） matrices. The excess lanthanum existing in the ultra-fine particles provided a source of electrons, which could be thermally exited into conduction band of La2O3 across the Schottky bartier. These electrons located in the conduction band of La2O3 had only to surmount the surface barrier （ electron affinity EA ） of the La2O3, in order to escape into vacuum. Since the Schottky barrier was smaller than the bandgap Es of La2O3, and La ultra-fine particles could narrow the thickness of depletion layer, the threshold of electron emission into the vacuum was reduced.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2009年第1期161-164,共4页
Journal of the Chinese Society of Rare Earths
基金
国家863项目(2002AA322010)
河南科技大学人才科学研究基金(05-079)资助项目
关键词
热阴极
发射机制
发射模型
超微粒子
稀土
thermionic cathode
emission mechanism
emission model
ultra-fine particles
rare earths
作者简介
郝世明（1975-），男，山西左权人，硕士研究生，讲师；研究方向：真空电子及薄膜.通讯联系人（E—mail：s_m_hao@126．com；haoshm6666@emails．bjut．edu．cn）
