基于太赫兹真空器件的微型阴极抑制膜特性研究

Study on the characteristics of mini-cathode anti-emission coating based on THz vacuum devices

为满足太赫兹真空器件对阴极的大电流密度、小电子注尺寸需求,利用双离子束辅助沉积技术在浸渍钪酸盐阴极表面沉积Ta/Zr抑制膜,并利用聚焦离子束刻蚀技术制备出发射面直径为100μm的微型热阴极。在此基础之上着重研究这种阴极的抑制膜特性,研究表明,Ta/Zr膜层比Zr膜层临界附着力更强,双离子束辅助沉积制备的Ta/Zr抑制膜比磁控溅射制备的Ta/Zr抑制膜更加致密,并且抑制发射寿命更长。阴极良好的抑制效果一方面是因为Ba扩散至Zr中形成高功函数物质,另一方面是因为Ta/Zr复合膜层高度致密有效抑制了Ba的扩散。

In order to meet the demand of THz vacuum devices for miniature electron beam with high current density,a kind of miniature cathode has been prepared by depositing Ta/Zr coating on impregnated scandate cathode surface via dual Ion-Beam-Assisted Deposition(Dual IBAD)and etching an emission zone with a diameter of 100 m via Focus Ion Beam(FIB).Based on the previous study,this paper focuses on the characteristics of anti-emission coating.It is shown in the experimental results that Ta/Zr coating prepared by dual Ion Beam Assisted Deposition(Dual IBAD)can suppress electron emission more effectively and has a longer life time than that prepared by magnetron sputtering.The reasons for the sound anti-emission performance are that composition with high work function is formed in the process of Barium diffusion into the Ta/Zr coating,and that Barium diffusion is effectively suppressed by the high dense Ta/Zr coating.