Hybrid Physical-Chemical Vapor Deposition of MgB2 Thin Films

本文主要研究了利用物理化学混合气相沉积（HPCVD）技术原位沉积外延MgB2超导体薄膜和多层薄膜。MgB2是一种传统的超导体，具有39k的高转变温度，像低tc超导体结一样有希望形成约瑟夫森结，但工作温度为25k。研究人员开发了HPCVD技术，生长出具有优异超导和输运性能的外延MgB2薄膜。本项目将进一步改进HPCVD技术，使其更易于控制和兼容于约瑟夫森结的多层沉积。该研究将模拟HPCVD的生长条件，测试各种反应器配置，并解决生长机制、合适的隧道阻挡材料和多层结构沉积等各种材料问题。适用于超导集成电路的25k约瑟夫森结的演示和大规模加工技术将对微电子工业产生重大影响。在这个项目中训练的学生将接触到物理学和材料科学，并获得在学术和工业环境中从事材料研究的重要技能。本文主要研究了新发现的MgB2超导体的薄膜沉积。与非传统的高tc超导体不同，MgB2是一种具有39 K高转变温度的传统超导体。这使得生产MgB2 Josephson结（用于超高速数字处理的超导集成电路中最基本的器件）变得更有希望。为了实现MgB2Josephson结和集成电路，需要一种与多层沉积兼容的薄膜技术。pi开发了一种创新技术，混合物理化学气相沉积（HPCVD），以生长具有优异超导和输运性能的外延MgB2薄膜。然而，这项技术还处于发展的早期阶段，需要改进。本项目将利用理论建模来指导HPCVD的改进，解决薄膜生长中的各种材料问题，并开发用于Josephson结的多层材料。该项目的成功将对微电子工业产生重大影响。在这个项目中训练的学生将接触到物理学和材料科学，并获得在学术和工业环境中从事材料研究的重要技能。

This research focuses on the in situ deposition of epitaxial MgB2 superconductor thin films and multilayers by hybrid physical-chemical vapor deposition (HPCVD). MgB2 is a conventional superconductor with a high transition temperature of 39 K, promising Josephson junctions like the low-Tc superconductor junctions but operating at 25 K. The PIs have developed the HPCVD technique and grown epitaxial MgB2 films with excellent superconducting and transport properties. This project will further improve the HPCVD technique to make it more controllable and compatible to multilayer deposition for Josephson junctions. The research will model the HPCVD growth conditions, test various reactor configurations, and address various materials issues in the growth mechanism, the suitable tunnel barrier material, and the deposition of multilayer structures. A demonstration of a 25-K Josephson junction suitable for superconducting integrated circuits and a large scale processing technique will have a significant impact on the microelectronics industry. Students trained in this project will be exposed to both physics and materials science and acquire skills important for their careers in materials research in both academic and industrial environments.Non-Technical Abstract This research focuses on the thin film deposition of the newly-discovered MgB2 superconductor. Unlike the unconventional high-Tc superconductors, MgB2 is a conventional superconductor with a high transition temperature of 39 K. This makes it more promising to produce MgB2 Josephson junctions, the most elemental devices for superconducting integrated circuits for ultrafast digital processing. To achieve MgB2Josephson junctions and integrated circuits, a thin film technique compatible with multilayer depositions is required. The PIs have developed an innovative technique, hybrid physical-chemical vapor deposition (HPCVD), to grow epitaxial MgB2 films with excellent superconducting and transport properties. However, the technique is in its very early stage of development and needs improvements. This project will use theoretical modeling to guide the HPCVD improvement, address various materials issues in the film growth, and develop multilayers for Josephson junctions. The success of the project will have a significant impact on the microelectronics industry. Students trained in this project will be exposed to both physics and materials science and acquire skills important for their careers in materials research in both academic and industrial environments.