“Centaurs” and ultra-thin films for the electronics of the future: nanoplasmonics for sensors and quantum computing

Development and fabrication of nanodevices are shaping today the electronics of the future. Nanotechnology allows the use of properties different from those of free atoms or molecules, as well as from the bulk properties of the substance consisting of them. This allows for creating materials that are more advanced, news devices, and systems. Alexander Baburin, Head of the Photon Devices Fabrication at FMN Laboratory, talked to Indicator.ru portal about the unique studies of nanophotonics and quantum plasmonics – relatively young research areas that study the operation of devices for controlling photons and vibrations of conducting electrons in metal-dielectric nanostructures. They can be used in a wide variety of fields: from sensors to quantum computing and communications.

- Alexander, how did you start your work? What is your team doing today?

- Ilya Rodionov and his team visited various laboratories in Europe, America and Asia to find the best solutions for the micro/nanofabrication center in Moscow. By my arrival in 2014, the team has already developed the basic routes for fabricating devices and purchased the necessary equipment. The center’s first challenge was a large-scale Russian project to fabricate a family of photonic devices based on the principles of nanoplasmonics, one of the trends at that time. The functioning of such devices is based on a very interesting phenomenon when the light can be focused in structures shorter than its wavelength due to plasmon resonance. Potentially, such devices can be used to manufacture key elements of new electronics, and these works are now actively implemented in promising devices and detectors of a new generation. In frames of the project, we have developed a unique technology for the production of almost ideal metal films, which brought to a fundamentally new level a solution to the main problem of plasmonics – losses.

It is all about epitaxial materials. Silver is by far considered the most preferred low-loss material, but it is very capricious. The metal has a high reactivity: just remember when silver jewelry darkens over time, oxidizing and sorbing gases from the atmosphere on the surface. The same happens when creating nanoscale devices. The deposition of a silver film requires a very clean medium and vacuum, but there are always the smallest particles and residual gases that interfere. In addition, silver has a strong surface tension, and this energy causes the material to collect in droplets, which prevents the creation of a continuous film. Its formation with standard approaches is possible only with a large thickness. However, such thick films are no longer suitable for the manufacture of plasmon devices.

- How exactly the process of deposition is going on?

- This is just my specialty, something that I studied, including why I was invited to the project. I began to study deposition technologies at my department, and the transition to work at FMN Laboratory has greatly expanded the possibilities of my researches and studying the properties of formed coatings. Specifically, to deposit single-crystalline silver films, we use the e-beam evaporation unit in a vacuum. We place the material in a cooled container (a crucible) where it is heated and evaporated with the help of a precision focused electron beam. The evaporated material is deposited on the surface of the substrate located above.

This approach is quite unusual for the fabrication of single-crystalline films. Initially, engineers used another kind of tool – much more expensive and complicated. These are molecular-beam epitaxy units. The principles of operation are very similar, but they use significantly lower deposition rates and high vacuum, and you can work with only one material on one device.

The method of e-beam evaporation has the worst parameters in terms of vacuum and, accordingly, the potential purity of the formed material. The uniqueness of the process developed by us allows not only to create almost ideal plasmonic films of metals but also to do this using methods and equipment of mass production. This is a much more valuable result than just a laboratory technology, even if it is unique. Thanks to our technology, we have already fabricated a number of unique devices. 

The full interview is available here (Russian version only).