The COST Action is an interdisciplinary research network that brings together researchers and innovators to explore a topic of their choice for 4 years. In this case, epitaxy experts from all over Europe came together more than 2 years ago, and the workshop in Vilnius marks the halfway point of this initiative.

 

Young researchers, students and invited guests present epitaxy-related research during the event. The seminar is organized by the research group of Dr. Renata Butkutė, a physicist at the FTMC Department of Optoelectronics. The official partner of the event the Lithuanian company Integrated Optics, which will present a prize to the author of the best oral presentation on Friday.

 

 

 

 

"Epitaxy is the very first process of technology development, where atom by atom multilayer crystal structures are grown in special equipment. These structures are then processed and applied to a wide range of devices - light emitting diodes (LEDs), lasers, detectors, sensors and others.

 

Since there are many materials that we grow, each has its own function - one helps light "escape" more easily, another is responsible for the wavelength of the laser, and so on", says Dr. Renata Butkutė, the seminar organizer, introducing the epitaxy.

 

The COST Action OPERA brings together scientists who are growing crystal structures, as well as modellers, theorists, experimenters and industry where the devices are used.

 

 

 

OPERA organizes workshops in European countries and focuses on the involvement, training and development of young scientists. Dr. Noelle Gogneau, Researcher Director at CNRS, Europe's largest fundamental sciences agency, who has come to Vilnius, talks about this in more detail:

 

"Epitaxy community in Europe is extremely important. We have a strong expertise and a strong know-now, but finally, the network was not completely constructed, so it was important to construct a larger community to improve the exchange and the discussion about epitaxy, which is at the base of innovations and development of devices we are using daily.

 

Without high quality, we cannot develop high-performance devices, and epitaxy is one of the most important part of it. It's crucial to master the development we have done already but also to move forward with new processes, new research, further development of today."

 

 

 

"The main achievements of the OPERA network are that we have organized lots of workshops in more than 2 years to increase the exchange and discussion about epitaxy in Europe. We also fund many short-term scientific missions, mostly for young researchers and students. We encourage them to do some experiments in nothern countries and improve the research and development.

 

It is extremely important to increase the formation and the experience of these young population, which is the researchers for tomorrow, and it is also a good manner to induce a better connection between the inclusive countries," stresses Dr. Gogneau.

 

She adds that COST Action OPERA promotes equality between male and female researchers (a discussion on this topic has also taken place at the workshop in Vilnius), and in two years the number of female speakers at the network's workshops has risen from 30-34% at the beginning to 47% this year.

 

The Head of the scientific network is also pleased with the stable funding, with around €50,000 per year for short-term research missions.

 

 

One of the organizers of the event is Aivaras Špokas, an engineer at the FTMC Department of Optoelectronics. He and his colleagues grow tiny crystals by epitaxy in special laboratories - clean rooms.

 

 

 

"We first bring an idea of what and how we want to grow to the workplace. Initially, there are a lot of calibration (testing) growths. This is where the most interesting 'magic' happens: since we want to create devices based mainly on quantum structures, we 'play' with the dimensions of the crystals, with the composition, the placement of the elements, and with the relationships between them. All this to achieve the desired physical or optoelectronic properties of the materials, which in our case are directly related to light emission, since the end result of the process is usually a LED or a laser.

 

For example, R. Butkutė's research group, where I work, creates micro-lasers; a quarter of a palm-sized wafer can hold hundreds of such lasers. They are so small that people don't even think about how they help us in our daily lives, but they are also applicable to niche areas - environmental monitoring, etc.,"says Aivaras.

 

The so-called calibration phase (consisting of dozens of smaller steps) takes about a month, when the necessary materials are grown and tested before the final device is built.

 

 

 

The task of Aistė Butkutė, an engineer in the FTMC Department of Optoelectronics, is to characterize the properties of these materials:

 

"Dr. Butkutė's group grows the samples, and in order to get to know them better, to see what is going on inside, my colleagues and I do the characterization. We mostly do temperature-based photoluminescence studies, i.e. we look at how the samples radiate or change their intensity depending on the temperature. We can then compare the structures we have - whether they are well grown, whether they have many defects, which of our innovations are working and which are not."

 

What's particularly interesting (and challenging) about this work is that you can't be sure of the exact result before you start the whole process.

 

"I would like to see the results of the experiments repeated successfully, but our research group is working on semiconductors with an exotic material - gallium arsenide bismide. It's like a loose horse, hard to handle. This is a novelty, not many groups in the world are doing this," adds A. Špokas.