纳米粒子薄膜热电子发射性能  

Study on emission properties of the nanopatical films

作　　者：刘燕文[1] 王小霞[1] 田宏[1] 朱虹[1] 张明晨[1] 李玉涛[1] 孟鸣凤[1] 陆玉新[1] 谷兵[1] 方荣[1] 

机构地区：[1]中国科学院电子学研究所,北京100190

出　　处：《中国科学：信息科学》2015年第1期145-156,共12页Scientia Sinica(Informationis)

基　　金：国家自然科学基金(批准号:61072025);国家重点基础研究发展计划(批准号:2013CB328900);国家高技术研究发展计划(批准号:2013AA8035040C)资助项目

摘　　要：微波真空电子器件广泛应用于雷达、卫星通信、电子加速器及未来军事前沿的高功率微波武器等方面,担当电子发射的阴极是微波真空电子器件中最为核心的部分.纳米材料具有许多不同于块体材料的物理化学特性,利用纳米材料对传统的扩散阴极进行表面改性,制备出热电子发射性能良好的新型阴极,对于推动高功率微波真空电子器件的发展具有十分重要的意义.本文采用直流磁控溅射复合金属靶的方法制备出粒径分布均匀的直径为20 nm的金属纳米粒子,并测试研究了纳米粒子薄膜的热稳定性.采用飞行时间质谱(To FMS)测试了真空本底和纳米粒子薄膜阴极、传统覆膜阴极等各种阴极蒸发物的成分,测试结果表明飞行时间质谱仪具有很高的灵敏度,比较了不同阴极蒸发速率的大小,发现纳米粒子薄膜阴极比普通覆膜阴极的蒸发速率降低约30%.研究了覆纳米粒子薄膜钡钨阴极的发射特性,阴极直流发射电流密度达到31.4 A/cm2,且拐点非常明显,寿命超过600小时;阴极的脉冲发射电流密度达到108 A/cm2,寿命达到1500小时.Microwave vacuum devices are used in a wide variety of areas, such as radar, space technology, electron accelerators and high-power microwave weapons at the future military frontiers. The cathodes, i.e., the electron sources, are the cores of the high-power microwave sources. Nanoparticles have many physical and chemical properties that their corresponding bulk materials do not have, such as surface effect and small-size effect,etc. Based on our previous work on the M-type cathode, we have proposed a strategy to develop a new type cathode. We deposited a layer of thin film of metal nanoparticles on the traditional Ba-W dispenser cathode.Thus the N-type cathode demonstrated some features different from the traditional M-type cathode. The study of the electron emission properties of this N-type cathode would promote the understanding on the electron emission and expand the applications of the nanomaterials. Nanoparticle thin films were grown by magnetron sputtering at room temperature. The results showed that the particle size of the films depended on the deposition rate in the nucleation stage of the films. The effect of thin film characteristics on thermionic emission of dispenser cathodes has been investigated. The chemical components of the vacuum background, the evaporants from an N-type cathode and an M-type cathode were respectively analyzed using a time of flight mass spectrometer（To FMS）.The results have proved that the To FMS is one of the best tools for studying the evaporation phenomena of impregnated cathodes. Finally, the electron emission performance of the N-type cathodes was studied. I-V characteristics showed that the DC emission current density was 30 A/cm2 and its lifetime was 600 h. The pulse emission current density was 108 A/cm2 and its lifetime was 1500 h.

关 键 词：微波真空电子器件 纳米粒子薄膜 热阴极 发射电流 蒸发 寿命 

分 类 号：TN12[电子电信—物理电子学] TB383.1[一般工业技术—材料科学与工程]