高温超导薄膜J_c与微波非线性相关性研究

采用微带谐振器技术研究高温超导薄膜的微波非线性问题,介绍了微波非线性的测试方法,描述了测试现象,定量表征了微波功率非线性。将微波非线性与临界电流密度Jc大小的关联性进行分析研究,发现两者关联性弱;同时验证了功率压缩测试方法对高温超导薄膜微波非线性的研究是可行的。     

高温超导薄膜微波非线性器件设计初探

本文讨论高温超导薄膜微波非线性器件的若干问题,包括材料建模,元件建模,器件参数建模,最后通过这些参数完成高温超导薄膜微波非线性器件综合等.试图通过非线性测试提取高温超导薄膜微波材料非线性模型,根据材料非线性模型建立非线性传输线模型,由非线性传输线模型建立各种微波无源元件模型,最后实现非线微波器件综合设计.     

第一讲 高温超导薄膜及微波器件应用

介绍了高温超导薄膜制备方法研究的进展和现状，对薄膜生长的一些技术，如外延生长高质量的薄膜对基片的要求，常用的基片，为了减小像硅和蓝宝石一类的重要基片与高温超导薄膜间的扩散以及改善晶格匹配采用的缓冲层技术等也作了简要的介绍，还介绍了薄膜的微波性质和用高温超导薄膜制血的微波无源器件。     

高温超导薄膜及微波器件应用

介绍了高温超导薄膜制备方法（如磁控溅射、脉冲激光淀积、电子束共蒸发、化学气相沉积等）研究的进展和现状．对薄膜生长中的一些技术，如外延生长高质量的薄膜对基片的要求、常用的基片、为了减小像硅和蓝宝石一类的重要基片与高温超导薄膜间的扩散以及改善晶格匹配所采用的缓冲层技术等也作了简要的介绍，还介绍了薄膜的微波性质和用高温超导薄膜制备的微淡无源器件．     

高温超导薄膜无源微波器件的应用

高温超导薄膜在微波器件中的应用,与常规导体相比可以减小器件的体积,重量,功率消耗和插入损耗,并且可以在液氮沸点附近工作,接近于卫星的环境温度100K,微波器件是在几个平方厘米的高温超导薄膜上制备的。这些薄膜必须要有最高的超导性能,如临界温度,临界电流密度以及微波表面电阻,因此高温度超导薄膜的应用受到制备大面积,高质量薄膜的限制,美国高温超导空间实验在1999年5月已经获得成功,使高温超导薄膜在微波器件中的应用成为现实。     

高温超导膜微波表面电阻Rs对微波滤波器插入损耗的贡献

利用微波电路仿真软件，分析高温超导膜微波表面电阻Rs对各种频率、各种级数的滤波器插入损耗的影响.结果给出:对于级数较少、频率较低的滤波器，使用Rs较高的薄膜或厚膜就可以得到很低的插入损耗;对于频率较高(高于6GHz),或极数较多（超过8极）的滤波器，就必须采用高质量的高温超导薄膜（Rs<1mΩ）. 关键词： 高温超导膜 微波滤波器 微波表面电阻 插入损耗     

高温超导窄带低插损小型化双工器的仿真研究

采用IE3D软件,利用全波电磁仿真方法设计研究了高温超导窄带低插损小型化微波双工器,采用的材料是在厚度为0.5mm介电常数为23.5的LaALO3衬底上用磁控溅射法制备而成的双面氧化物高温超导薄膜Y B C O.利用在微波范围内,高温超导薄膜的Q值比常规导体高1～3个数量级的特点和其高介电常数的特点,实现了器件的低插损和小型化.     

高温超导微波谐振器非线性测试及应用研究

本文对高温超导微波谐振器的非线性特性做了测试，对测试结果进行了分析t并对该谐振器的构造方案做了分析．发展并实现了利用中等功率电平进行微波临界电流附近高温超导强非线性特性的测试方案．     

微波近场显微镜及其在超导薄膜和衬底材料特性无损检测上的应用

高温超导薄膜的微波性能受制备工艺和衬底材料性能的影响,常常出现空间不均匀分布,因此,无损检测大面积超导薄膜及衬底材料的微波性能,研究影响局域微波性能的因素,是高温超导微波器件应用研究中的一个重要方面．我们设计和制造了一套同轴谐振腔型微波近场扫描显微镜,利用该显微镜研究了金属薄膜样品微波表面电阻和介质材料的介电常数的空间分布,给出了其空间分辨率并分析了影响空间分辨率的因素．利用这套微波近场扫描显微镜,对大面积ＬａＡｌＯ３单晶衬底材料介电常数的空间分布进行了测量,并分析了其测量精度．最后,利用这套微波近场扫描显微镜,研究了ＹＢａＣｕＯ薄膜平面微波器件的微波表面电阻的分布情况,对影响其局域微波性能的因素做了初步分析     

高温超导滤波器两种刻蚀方法的研究

在高温超导滤波器的制备过程中,针对所使用的高温超导薄膜的特点,采用了两种刻蚀方法——湿化学刻蚀法和离子束刻蚀法,设计对比了两种刻蚀的制作流程及其优缺点,并用两种方法分别制备了高温超导滤波器,对微波特性做了对比分析。得出离子束刻蚀对超导薄膜的性能影响要小一些,用此方法制备的高温超导滤波器具有更好的微波特性。     

微波电子回旋共振-化学气相沉积SiN_x薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽、透光率高的特点，总结了透光谱、折射率、光隙能随微波功率、基片温度的变化关系     

Synthesis of nanocrystalline ZnTiO3 perovskite thin films by sol-gel process assisted by microwave irradiation

Nanocrystalline ZnTiO₃ thin films have been grown on Si (1 0 0) at room temperature by using simple, cost effective sol-gel process assisted by microwave irradiation for thermal treatment. For comparison purpose the deposited films have subjected to two kinds of annealing treatments: first set by using conventional annealing and second set by irradiating the deposited films at different microwave powers for 10 min. In both treated films, formation of cubic phase ZnTiO₃ structure has been observed. It is evident that there is a dramatic structural modification when the deposited films are exposed to microwave. It is evident that there is a dramatic change in the morphological properties of the films irradiated in microwave compared to the conventional annealing temperature. Microwave exposed films have shown 19% of Zn, 19% of Ti and 62% of O in the films close to the stiochiometry of the ZnTiO₃, where as annealed films have shown 18% of Zn, 17.5% of Ti, and 64.5% of O in the films of ZnTiO₃. Plausible mechanism for the formation of cubic phase of ZnTiO₃ at low microwave powers has also been discussed. This new innovative microwave heating could open a door for the advanced technologies to cut down the process cost in post treatment of the materials.     

Microwave-induced low-temperature crystallization of amorphous Si thin films

Microwave heating was utilized for low-temperature crystallization of amorphous Si (a-Si) films. Microwave heating lowered the annealing temperature and reduced the annealing time. By microwave heating the hydrogen in the amorphous films was diffused out long before the nucleation of polycrystalline Si (poly-Si). The combination of NiCl₂ coating on a-Si and microwave heating greatly reduced crystallization temperature. The combination of metal-induced crystallization and microwave-induced crystallization might be a useful technique to develop high-quality poly-Si films at low temperature.     

Perpendicularly oriented barium ferrite thin films with low microwave loss,prepared by pulsed laser deposition

Barium ferrite(Ba M) thin films are deposited on platinum coated silicon wafers by pulsed laser deposition(PLD).The effects of deposition substrate temperature on the microstructure,magnetic and microwave properties of Ba M thin films are investigated in detail.It is found that microstructure,magnetic and microwave properties of Ba M thin film are very sensitive to deposition substrate temperature,and excellent Ba M thin film is obtained when deposition temperature is 910℃ and oxygen pressure is 300 m Torr(1 Torr = 1.3332×10~2Pa).X-ray diffraction patterns and atomic force microscopy images show that the best thin film has perpendicular orientation and hexagonal morphology,and the crystallographic alignment degree can be calculated to be 0.94.Hysteresis loops reveal that the squareness ratio(M_r/M_s) is as high as 0.93,the saturated magnetization is 4004 Gs(1 Gs = 10~4T),and the anisotropy field is 16.5 kOe(1 Oe = 79.5775 A·m~(-1)).Ferromagnetic resonance measurements reveal that the gyromagnetic ratio is 2.8 GHz/kOe,and the ferromagnetic resonance linewith is108 Oe at 50 GHz,which means that this thin film has low microwave loss.These properties make the Ba M thin films have potential applications in microwave devices.     

Low field microwave absorption of YBa2Cu3O7−δ thin films

The modulated microwave absorption in YBa₂Cu₃O_7−δ thin films was studied as a function of temperature, modulation amplitude, and microwave power. The comparative nature of weak links in YBaCuO thin films, ceramics, and powders is discussed.     

Technology of Production of Integrated Devices for Millimeter Wave Electronics Based on High-Temperature Superconducting Films

In the work, the results on the analysis of phase transitions in amorphous films Y-Ba-Cu-O under their annealing are presented for the purpose to obtain high-temperature superconducting film samples intended for microwave applications. The analysis and choice of material for substrates have been carried out with the purpose to create integrated microwave circuits, using the high-temperature superconducting films. The method of producing the epitaxial Y-Ba-Cu-O films for microwave electronics has been justified. With the purpose of creation of the hybrid integrated circuits with application of high-temperature superconductor films, the data on producing the ohmic contacts with low transitional resistance in a system metal - high temperature superconducting film are presented. The analysis of critical parameters and microwave properties of YBa₂Cu₃O₇ films under their annealing in vacuum has been carried out. The justification of temperature regimes of contact photolithography concerning the YBa₂Cu₃O_7– films is given. The influence of oxygen implantation on structural properties and critical parameters of YBa₂Cu₃O_7– is demonstrated.     

Use of the Phenomenon of High-Temperature Superconductivity for the Creation of Integrated Devices of Microwave Electronics

Physical fundamentals justifying the use of integrated microwave circuits based on films of high-temperature superconductors in microwave electronics are presented. The peculiarities of calculations of high-temperature superconducting film microwave elements are shown. The technological conditions of the creation of integrated microwave devices based high-temperature superconducting on films are analyzed.     

Low-field microwave absorption in pulse laser deposited FeSi thin film

Low field microwave absorption (LFMA) measurements at 9.4 GHz (X-band), were carried out on pulse laser deposited (PLD) polycrystalline B20 cubic structure FeSi thin film grown on Si (111) substrate. The LFMA properties of the films were investigated as a function of DC field, temperature, microwave power and the orientation of DC field with respect to the film surface. The LFMA signal is very strong when the DC field is parallel to the film surface and vanishes at higher angles. The LFMA signal strength increases as the microwave power is increased. The LFMA signal disappears around 340 K, which can be attributed to the disappearance of ferromagnetic state well above room temperature in these films. We believe that domain structure evolution in low fields, which in turn modifies the low field permeability as well as the anisotropy, could be the origin of the LFMA observed in these films. The observation of LFMA opens the possibility of the FeSi films to be used as low magnetic field sensors in the microwave and rf frequency regions.     

高质量高取向(100)面金刚石膜的可控性生长

应用微波等离子体化学气相沉积技术, 在低气压下对(100)晶面金刚石膜的表面形貌、质量、取向和生长率进行了可控性生长研究. 结果表明: 基片温度与甲烷浓度对(100)晶面金刚石膜的生长存在耦合规律. 为了获得表面形貌相似的(100)晶面金刚石膜, 在沉积过程中, 增加碳源浓度的同时需要同时升高基片温度; 当甲烷浓度为3.0%, 基片温度从740 ℃上升至1100 ℃ 的过程中, 金刚石膜的晶面取向变化可分为五个阶段, 其中当基片温度在860 ℃至930 ℃时, 很适合高取向(100)晶面金刚石膜生长; 另外, 金刚石膜的质量和生长速率分别与基片温度和甲烷浓度成正比. 为了获得高质量高取向(100)晶面金刚石膜, 应当选择合适的基片温度和甲烷浓度.