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ITMO University: nanotechnology using ZEISS double beam station with Raith nanolithography system

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ITMO University: nanotechnology using ZEISS double beam station with Raith nanolithography system

We talked to Alexander Golubok, Doctor of Physics and Mathematics, Head of Nanotechnology and Material Sciences Department at ITMO University about current and upcoming trends in the nanotechnology area, the role of ITMO University in technology development and the application of ZEISS CrossBeam Neon 40 workstation with the prefix Raith ELPHY Plus for creation and analysis of micro- and nanostructures.

Everybody is talking about nanotechnology these days. Would you please tell us what it is?

There is a formal definition for nanotechnology: it is thought that if you create or deal with objects measuring less than 100 nm, this is the nanotechnology area. However, this is not quite correct from a physics perspective. When we talk about nanotechnologies, it’s not just the size of objects that matters; it’s the new properties and new qualities we have obtained as well. Nanomaterials are materials with properties that can be controlled by nanotechnology.

How do each of us come across them in our everyday life?

In fact, we all have been using micro- and nanotechnology innovations in optical engineering and photonics, such as lasers and light-emitting diodes, for a long time already. When we switch TV channels using a remote control, unlock a car door, see a clear color picture on our smartphone or display screen, we are using micro- and nanotechnology innovations. Many flashlights and traffic lights already use light-emitting diodes. Micro- and nanotechnologies are all around us in our everyday life and they have found countless applications.

As for nanotechnologies in the medical industry, it’s worth mentioning the promising area of targeted drug delivery to the intercellular space. In the future, they will find extensive use in security systems because security issues are becoming especially important today.

Actually, nanotechnologies is the area where physics, chemistry, biology, computer science, and modeling all go hand in hand. This is a complex area and the findings can be applied in totally different spheres. In fact, there are no separate areas of mathematics, physics, chemistry or computer science. There is nature; so, to understand the laws of nature, scientists had to structure what they know about it and divide it into disciplines as, otherwise, it would be impossible to study it. Now is the time to get it all back together. Nanotechnologies are the very same area where such incorporation takes place in real life. Most studies generally feature an application component, it’s just that some of them deliver application results in as little as one year and others in 50 years.

How was your Nanotechnology Center established at ITMO University?

Several dozens of nanotechnology research and educational centers were established as part of the Russian nanoindustry development program. The Ministry of Education financed the procurement of advanced equipment for these centers. ITMO University won a contest and was awarded a grant to establish such a center. So, 8 years ago the University opened the Nanotechnology Research and Educational Center, with equipment concentrated in five discipline-related clusters, mostly at the Photonics and Optical Information Technology Department.

ITMO is a national research university, part of the 5–100 Program. Of course, we need state-of-the-art equipment to maintain the highest level of research and we do use such equipment for research conducted by various departments for various purposes.

This is why we selected ZEISS CrossBeam Neon 40, a double beam station with the Raith ELPHY Plusattachment, among other equipment, for our cluster. It’s a high-technology device, totally new for us, and which is now our key tool. We use it for visualization and diagnostics of nanoobjects, as well as for creation of micro- and nanostructures, which have become a new line in our research.

This is precise equipment with high vibration requirements. It transpired that it is quite difficult to install such equipment in a city due to numerous vibration sources. Nevertheless, we managed to find a location that meets all vibration and electrical noise requirements. Although this is the very center of the city and we are surrounded by Bolshaya Neva and Malaya Neva, we are far from tramways and the metro does not have much influence. The location was eventually transformed into a facility for equipment operation and research.

Could you please tell us about CrossBeam applications?

When it comes to modern nanotechnology, there are three major fields: high resolution diagnostics, creation of nanostructures, and nanomanipulation. CrossBeam is used in all three fields of application.

The first application is diagnostics. Any technology requires diagnostics and parameter control. When we deal with nanoobjects, we cannot learn something at a glance; this is why fine visualization and diagnostics are very important. We work with objects that cannot be seen even with an optical microscope but we have to control their parameters. This is exactly what CrossBeam does.

The second application is the creation of nanostructures. Most of the structures created are planar nanostructures. CrossBeam has a number of attachments to create three-dimensional nanostructures. For example, the gas injection system with certain precursors enables us to focus the electron beam, break down organometallic molecules, and create metal carbon (e.g. platinum-carbon or tungsten-carbon) whiskers. Then we can create three-dimensional framework nanostructures on this basis. We use these structures a lot in our work. In addition, our CrossBeam system is fitted with the Raith lithography attachment that offers a wide range of capabilities: we can etch the required structures on a sample and control all parameters.

Another fast developing application is nanomanipulation, i.e. movement of nanoobjects to nano- or microscopic distances. We use special manipulators with a nanometer step to move nanoparticles with a special needle. If we also use a focused electron beam, we can manipulate and move the particles, assemble special nanostructures, create nanoantennas, model fragments of metamaterials, and produce nanomechanical oscillators. Now there are many researchers dealing with nanotechologies, but we at ITMO ventured into this area before it came into fashion.

Could you please tell us more about some of your projects? What results did you achieve?

Let me give you an example: we are now studying nanomechanical oscillators. A simple oscillator is an oscillating, spring-mounted ball. What we do is create whiskers, that is, one-dimensional, threadlike structures that can swing and oscillate like a spring ball. We measure their resonance response. Why do we need it? There is a purely fundamental interest in these objects from a quantum mechanics perspective. On the other hand, there is a practical interest because they can work as sensors. For such whiskers, the frequency of oscillations depends on their mass. If the mass of a whisker changes, e.g. one molecule settles onto it, the frequency of oscillation also changes. This is how you can weigh one molecule. In some studies, these nanomechanical oscillators are used to weigh even single atoms. Today, it is possible to create more complex framework nanostructures and coupled oscillators on the basis of these structures, which is also what we are doing.

Another project is optical microresonators with whispering-gallery modes, which can be used in photonic elements. This is a very interesting and promising area. The name comes from acoustics: if you come close to a wall in a round room (for example, in a cathedral) and start whispering, the sound will go round the room reflecting from the wall over and over again almost without losses and will finally come back to you from the other side. Light can travel in a similar way in a micro-sized optical resonator due to a phenomenon known as total internal reflection. In this case, its characteristics may be even better than those of mirror resonators on a beam table or in laser housings; in addition, their dimensions range from several centimeters to several kilometers, as, for example, in laser gravitational antennas. These miniature resonators with unique characteristics may be used in a variety of photonic, laser, and hybrid devices, optical data processing and transmission systems, and so on — the applications are many and diverse.

Are you involved in any multidisciplinary projects, for instance, those related to biology?

We have a group in the Department that studies microfluid systems. The head of the group is Professor Evstrapov. There is a promising line of research called Lab-on-a-Chip. It allows for very fine, for example, chemical experiments with molecular structures or individual live cells. In chemistry or biochemistry, you need to take one substance or cell, link it to another substance, molecular structure or cell, and study their interaction. However, if you use advanced silicon microtechnology, it is possible to create microchannels in silicon or glass, make fluids move along these channels, meet and mix their flows. Molecules may be finely separated by electrophoresis: different molecules in a medium move with different speed in an electric field, so they can be separated and detected. This kind of microfluid systems is one of our projects. The properties of such systems improve significantly if nanostructures are built in these microchannels. We can create chromatographic structures or traps for certain molecules and cells. This is one of the current trends, very popular now all over the world.

Could you please tell us about your unique projects or studies you have pioneered?

One of the unique projects we are implementing, including with the use of CrossBeam, is a probe microscope module to be used in an electron microscope. We want to come up with a competitive solution that would combine an electron microscope and a probe microscope in a single system. Both electron and probe microscopy provide data and complement each other when materials are studied at the nanoscale level. I don’t think it is that easy to determine the mechanical properties of a material using an electron microscope without expensive, specialized devices. However, if you combine these methods and use a probe, it is possible to determine these characteristics. Sometimes it may be important, for instance, in nanotubes where it is not enough to see their dimensions; you have to measure Young’s modulus and other mechanical characteristics. A combination of different analytical methods in one device is an exciting prospect. A probe attachment will soon be a common thing, just like an X-ray microanalysis attachment to any scanning electron microscope. X-ray microanalysis is already an integral component of any research. Without it, you can just look; with it you can measure the spectrum and determine the composition of elements. If you add a probe to it, you obtain a set of new characteristics and data. In fact, we have already manufactured a similar device and are now working on its commercial version.

Second, we make nanomanipulation systems by combining an electron beam and a mechanical needle. The CrossBeam system has a special model, a micromanipulator, that enables the mechanical handling of objects and their movement. It was discovered that when the micromanipulator needle is exposed to an electron beam, it gets charged and attracts the object with an electric field. The researcher may not only move the object mechanically but also pick it up with the tip of the needle and transfer it to another sample or to another part of a sample. Then the object is dropped exactly where it is needed. We have improved this method: we make the needle ourselves, fix it to the manipulator, and manipulate the object using this thin nano-sized probe. This method can be used to create various objects, such as nanoantennas and structured nanosystems.

Do your colleagues from other institutions come to you for help with their application tasks?

We use this device for Department and University projects, but we are open to related areas and joint projects. We are actively cooperating with the Ioffe Physics and Technology Institute: we created photonic elements with whispering-gallery modes and conducted research for OJSC Avangard.

We also took part in a special educational project by ROSNANO when they organized training for employees from their engineering companies working in the nanoindustry. Training ROSNANO engineering companies was an absolutely novel idea. Employees from five engineering companies from St. Petersburg and Kazan attended lectures and practical classes and took a closer look at nanotechnology equipment, including ZEISS CrossBeam. The focus was on practical studies, know-how, and skills. It was a retraining course for engineers from different disciplines, based on their companies' long-term objectives in the nanotechnology area.


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