Superconducting thin films have been of tremendous interest in the scientific community since their discovery in 1986 by the Nobel Prize winning scientists Alex Muller, Bednorz and Cooper. Since then, great advances have been made in developing novel materials, fabrication techniques and device applications.
Superconducting thin films are materials that display zero resistive loss when maintained below a critical temperature. They are increasingly being used in a range of applications such as magnetic resonance imaging, electromagnetism and low noise amplifiers. As thin film devices offer greater flexibility and enhanced performance over bulk superconductors, they are becoming a popular choice in the electronics industry.
The most common type of superconducting thin film is the high temperature superconductor (HTS). HTS materials allow for low loss electrical transmission at temperatures higher than their predecessors, and are capable of working under higher power densities. This makes them useful for applications where bulk superconductors may have limited utility.
The means of fabricating superconducting thin films is split between sputter deposition and chemical vapor deposition (CVD). In general, sputter deposition is used for thicker films, but may not be suitable for fine technical structures due to a lack of resolution. CVD is preferred for relatively thin films, high resolution and uniformity.
The thin films can be further coated to create devices such as multilayered structures and high temperature superconducting Josephson junctions. Multilayer structures involve creating several thin films of differing levels of resistance. This allows the material to be tuned to respond to a range of forces and temperatures, making them suitable for applications in magnetometers and thermocouples.
High temperature superconducting Josephson junctions are actively used in high speed digital electronics. These devices involve the use of two superconducting layers on either side of a thin insulating layer. When illuminated with an appropriate frequency, the junction is able to conduct current with zero resistance. This makes them extremely useful for high speed switching applications.
Superconducting thin films are becoming an increasingly important part of the electronics industry. Their unique properties, coupled with the ability to create a range of different device structures, allow them to be used in a wide variety of applications. As further progress is made in the development of novel materials and fabrication techniques, superconducting thin films are likely to continue to be at the forefront of the electronics industry.
