NSF/ONR: Advanced Processing, Characterization and Properties of Epitaxial Multilayer Superconductor Heterostructures and Devices

小行星9421718 了解高温超导体、金属和超导体之间界面的结构和性质是薄膜外延结构性质的关键。 界面的结构和化学组成决定了薄膜中外延生长和缺陷的性质，这些性质直接影响输运性质和器件特性。该提案的目标是：先进超导器件所需的多层异质结构的原位加工。 主要重点将放在氧化钇，氧化钡和氧化铜超导材料系统。 薄膜多层异质结构将使用多靶保持器通过脉冲激光沉积进行处理，其中在单个腔室中可以生长多达五种不同的膜。 通过用激光反射镜替换其中一个靶，可以将激光能量引导到衬底上并实现原位原子级清洁。 应力和应变的建模将进行理解的外延生长和薄膜中的缺陷含量的性质。 这些结果将与界面的原子结构和化学组成以及薄膜中缺陷的性质相关。 将优化薄膜的外延质量和缺陷含量，以实现最高理论超导温度Tc（约94开尔文）和临界电流密度（Jc大于500万安培）。每平方厘米在77开尔文）的高性能器件。 优化的薄膜将用于制造一些高性能的测辐射热计（高响应或高速）。 超导材料提供了一种有吸引力的节能方式，以非常低的损耗传输电力。 然而，为了利用这种超导特性，材料必须过冷。 此外，对于实际应用，这些超导体必须内置到设备中。 为了最大化应用，需要以最小程度的冷却来操作这些设备。 通过理解多层超导器件的工艺，可以预期该技术在新的电子器件中的更广泛应用可能成为可能。 ***

9421718 Narayan Understanding of the structure and properties of interfaces between high-temperature superconductors, metals and dielectrics holds key to the properties of thin film epitaxial structures. The structure and chemical composition of interfaces determines the nature of epitaxial growth and defects in thin films which directly affect transport properties and device characteristics. The objective of this proposal is: In-situ processing of multilayer heterostructures needed for advanced superconductor devices. The primary focus will be on yittria, barium oxide, and copper oxide superconducting materials systems. Thin film multilayer heterostructures will be processed by pulsed laser deposition using a multitarget holder where up to five different films can be grown in a single chamber. By replacing one of the targets with a laser mirror it is possible to channel the laser energy on the substrate and achieve in-situ atomic level cleaning. Modeling of stresses and strains will be carried out to understand the nature of epitaxial growth and defect content in thin films. These results will be correlated with atomic structure and chemical composition of interfaces and nature of defects in thin films. Epitaxial quality and defect content of thin films will be optimized to achieve highest theoretical superconducting temperature Tc (about 94 Kelvin) and critical current density (Jc greater than 5.0 million amps. per square cm at 77 Kelvin) for high performance devices. The optimized thin films will be used to fabricate a few high-performance bolometers (high responsivity or high speed). Superconducting materials offer an attractive energy conserving way of transmitting electricity with very low losses. However, in order to capitalize on this superconducting property, the material has to be super cooled. Further, for practical applications these superconductors have to be built into devices. In order to maximize the application, one needs to operate these devices with m inimum degree of cooling. By understanding the process of multilayer superconducting devices, it is anticipated that a broader application of this technology may become possible into new electronic devices. ***