Yttrium Barium Copper Oxide Thin Film for Microwave Communications

这一小型企业创新研究第一阶段项目概述了一项计划，旨在确定功率不断增加的薄膜高温超导(HTS)微波器件性能下降的物理根源。薄膜高温超导最有前途的应用是高频信号处理。由YBa2Cu3O7-x(YBCO)薄膜制成的在77K下工作的无源微波器件，如谐振器、滤波器和延迟线，显示出比传统材料显著改善的性能。然而，通过这些设备传输的信号功率只有10毫瓦左右。大多数商业应用，特别是蜂窝通信，需要功率级别超过10瓦的信号处理。即使是最高质量的薄膜超导体，在输入功率仅为5瓦时，其性能也会急剧下降！高质量的外延YBCO薄膜将通过激光烧蚀生长，并故意改变微结构特征，如改进的外延、化学掺杂和增强的晶界；然后通过在微带谐振器中进行图案化来表征所产生的薄膜，以评估其在77K下的微波性能。这些结果将使第二阶段的工作集中在最有希望的放大和电路制造方法上。

This Small Business Innovation Research Phase I project outlines a program to determine the physical origins of the degradation in performance of thin-film high-temperature superconductor (HTS) rnicrowave devices with increasing power. The most promising application for thin-film HTS is high-frequency signal processing. Passive microwave devices such as resonators, filters, and delay lines fabricated from YBa2Cu3O7-x (YBCO) thin films and operated at 77K have shown dramatically improved performance over conventional materials. However, signal power levels transmitted through these devices are on the order of only 10 milliwatts. Most commercial applications, in particular cellular communications, require signal processing with power levels exceeding 10 watts. The performance of even the very highest quality thin-film superconductors degrades dramatically at only 5 watts of input power! High quality, epitaxial YBCO films will be grown by laser ablation with deliberately altered microstructural characteristics, such as improved epitaxy, chemical dopants and enhanced grain boundaries; then the resulting films will be characterized by patterning into microstrip resonators to evaluate their microwave performance at 77K. These results will allow the Phase II effort to focus on the most promising methods for scale-up and circuit fabrication.