太赫兹行波管输能窗用复合金刚石膜的设计  

Design and fabrication of composite diamond window for terahertz TWT

作　　者：李莉莉[1] 丁明清[1] 杜英华[1] 冯进军[1] LI Lili;DING Mingqing;DU Yinghua;FENG Jinjun(National Key Laboratory of Science and Technology on Vacuum Electronics,Beijing Vacuum Electronics Research Institute Beijing 100015,China)

机构地区：[1]北京真空电子技术研究所微波电真空器件国家级重点实验室,北京100015

出　　处：《太赫兹科学与电子信息学报》2018年第3期374-377,共4页Journal of Terahertz Science and Electronic Information Technology

基　　金：国家重点基础研究发展计划("973"计划)资助项目(2013CB933602);装备预先研究资助项目(31512010502-3)

摘　　要：为解决现有多晶金刚石用于太赫兹(THz)真空电子器件输能窗存在慢性漏气风险的技术难题,介绍了一种高断裂强度、良好真空密封性能、低微波损耗的新型超薄复合多层金刚石膜的研制方法。该复合超薄金刚石膜采用微波等离子体化学气相沉积(MPCVD)技术,通过合理的结构设计和优化工艺,实现微米晶金刚石(MCD)和超纳米晶金刚石(UNCD)交替沉积的三明治结构。测量100μm厚不同结构的复合膜断裂强度,是同样厚度的MCD的2~3倍。将研制的复合多层金刚石膜用于180 GHz和220 GHz太赫兹行波管输能窗,通过气密性检测,漏率≤1×10^(-10) Pa?m^3/s。窗的冷测结果显示,180 GHz窗的S_(11)≤-15 dB(10 GHz带宽),220 GHz窗的S_(11)≤-10 dB(20 GHz带宽),均具有良好的射频(RF)性能,满足使用要求。为太赫兹行波管输能窗的研制提供了一种成本低、可靠性高的超薄金刚石膜的技术途径。To overcome slow leaking problems of the Micro-Crystalline Diamond（MCD） window, a study on an extremely thin composite diamonds for the windows of the Terahertz（THz） wave Traveling Wave Tubes（TWTs） is presented. The composite diamond is prepared by Microwave Plasma Chemical Vapor Deposition（MPCVD） method. To reinforce the mechanical properties and air tightness, MCD is deposited incorporated with Ultra-Nano-Crystalline Diamond（UNCD）. A 100 μm thick composite film is designed and fabricated. The fracture strengths of the composite films with thin layers of UNCD are 2-3 times higher than those of the MCD films. The results of the leak test show the maximum leak rate of the windows is less than 1×10（-10） Pa·m3/s. 180 GHz and 220 GHz TWT composite diamonds windows are assembled. Results of the Radio Frequency（RF） tests of the two windows show that S（11）≤-15 d B（in range of 10 GHz） and S（11）≤-10 d B（in range of 20 GHz） respectively, indicating a good RF performance. This work provides a novel approach for the fabrication of extremely thin diamond windows for THz TWTs.

关 键 词：超纳米金刚石 微米金刚石 断裂强度 传输损耗 

分 类 号：TN104[电子电信—物理电子学]