Research into new materials for electronics at MIREA
Fundamental and applied research of new materials
"To a large extent, the conventional electronic component technologies exhausted their potentialities due to the fundamental limitations of the properties of materials", says one of the founders of the research team, Associate Professor of the Department of Physics of Condensed Matter Natalia Sherstuk, Ph.D. "The problem is not so much the inability to produce thin functional layers of the desired quality, but the fact that the structure of the conventional semiconductors not allows to improve the integration of microelectronic elements and to reduce their size to the extent necessary. Therefore it is necessary to look for not only new engineering solutions but for new materials".
In creating the non-volatile memory the use of ferroelectric materials is quite a promising area. The memory based on such materials can be characterised by very high data storage reliability. In contrast to ferromagnets, ferroelectrics are insensitive to magnetic fields, and are highly resistant to radiation. Due to this, the ferroelectric memory has good prospects in space exploration, military equipment and other areas related to the operation in extreme conditions. In particular, in the 1970s it was used in the computers of Voyager spacecraft.
Currently, promising areas are related to the application of multiferroics with the properties of both ferroelectrics and ferromagnets, as well as the so-called metamaterials, the artificially created materials with desired properties, such as photonic crystals. An important interdisciplinary problem is the study of the transient dynamics when the properties of such materials are switched on the terahertz frequencies. In the development of photonic crystals the research team has achieved good practical results that can be used to create devices, and several patents were received that attracted the attention of major international companies.
A wide range of issues is related to the introduction of optical technology in computer systems so that the operational speed of the latter can be determined by the highest known rates of modern physics, the speed of light. However, the existing prototypes of an optical processor are characterised by large dimensions at a low data processing rate, so a combination of traditional and optical technologies, which includes optical switching of the functional properties of materials, has good prospects. Optical switching of ferromagnets is already implemented, i.e. a change in the magnetisation of the medium under the influence of femtosecond laser pulses, the next step is the switching of the properties in ferroelectrics and related materials. This topic is interesting from the fundamental and applied points of view. The research is being conducted in the laboratory "Ultrafast Dynamics in Ferroics". At this stage, the theoretical basis is created, i.e. a mathematical model of ferroelectric switching under the optical radiation.
Another area of research is the creation of biocompatible materials for electronic devices, in particular, ferroelectrics that are safe for the living cells. The research team studied the ferroelectric and piezoelectric properties of the peptide micro- and nanostructures that are growing by self-assembly, and are relative cheap. Implementation of biocompatible microelectronic devices that can be implanted in humans opens up new opportunities for neurosurgery and other areas of medicine.
The practical findings obtained by the research team in various research areas are protected by seven patents, and three more patent applications are subjects for patent examination.
Original techniques, unique equipment
The laboratories are equipped with modern devices that allow not only to address the most pressing scientific problems but also conduct education.
The unique device patented by the research team is a non-linear optical microscope the prototype of which is assembled and used in the studies. The principle of operation is based on the registration of second harmonic radiation that occurs under the influence of laser radiation on the investigated object, which allows the non-destructive testing of the magnetisation of ferromagnetic materials, ferroelectric polarisation as well as the crystal symmetry. Moreover, the control of dynamics of the listed characteristics is possible, and there are no restrictions on the size of the object.
For signal recording in the non-linear optical microscope is used a relatively "slow" photomultiplier, so the resolution of the measurement in time is about 5 ns. Therefore, to study the ultrafast dynamics in ferroics is used the so-called optical pump-probe method, which provides time resolution to hundredths of a picosecond. The essence of this method is the optical recording of the changes in the material under the influence of a powerful light source with ultra-short pulse (less than 0.1 ps).
Most femtosecond lasers in the laboratories are manufactured in Russia by the Avesta-Project company from Troitsk. According to N.Sherstuk, these lasers are very reliable and well suited not only for research but also for educational process.
An interesting solution was created on the basis of the scanning nearfield optical microscope Alpha 300 (WITec), which can also operate in the atomic force microscopy mode. By means of a special non-fibre optical system the radiation of a femtosecond Ti:sapphire laser is directed in the microscope, and it is possible to conduct a high-resolution study of the nonlinear optical response of the ferroelectric and multiferroic samples, two-dimensional semiconductors and other nanoscale objects.
For low-temperature research a nitrogen helium cryostat will be used in the laboratory, which can be used for optical measurements at temperatures up to 10 K.
The study of the surface of samples with nanometer resolution is carried out on a compact low vacuum scanning electron microscope JEOL JSM-6390LV.
Cooperation with leading Russian and international research teams
"We are actively cooperating with the Department of Quantum Radio Physics of the Faculty of Physics of the Lomonosov Moscow State University, which study similar problems", says N.Sherstyuk about the collaboration with colleagues from other institutions. "Our cooperation with the Southern Scientific Center of the RAS and the Southern Federal University (Rostov-on-Don), in which one of the best teams involved in the manufacture of nanoscale ferroelectric materials not only in Russia but also globally is working. Our long-standing partner, the Institute of Crystallography of the RAS, with which a large number of projects are implemented. We cooperate with the St. Petersburg Ioffe Physical-Technical Institute of the RAS in the study of ultrafast dynamics in ferroics as well as in the field of laser crystallization of ferroelectric materials. In 2013, some joint projects with the Moscow Institute of Electronic Technology were launched as well".
A key foreign partner, the launch of activities with which provided the basis for the research in ultrafast dynamics in ferroics is the team of professor Rasing from the Institute for Molecules and Materials of the University of Nijmegen (Netherlands). Members of this team Alexey Kimel is currently leading an ultrafast dynamics in ferroics project implemented under a megagrant of the Russian Government. There has been long-standing cooperation between the team of E.Mishina and colleagues from the Japanese University of Saitama who are engaged in research in the field of physical chemistry and biology. Some fruitful cooperation has also been established with scientists from the University of Aveiro (Portugal) who explore ferroelectric materials by the atomic force microscopy.
In neighbouring states N.Sherstuk pointed to the Institute of Applied Physics of the Academy of Sciences of Moldova, "We use new semiconductor materials developed in Kishinev, in particular, they were first object of research using a non-linear optical microscope. Now colleagues are successfully addressing the problem of obtaining the two-dimensional semiconductors of transition metal dichalcogenide, which, unlike grapheme, have a forbidden zone and can be used in conventional microelectronics".
The leaders of the team believe that the cooperation with other institutions is important not only in terms of information exchange but also for training of young reseachers. In addition to research, all members of the team including students are involved in communications with Russian and foreign colleagues and regularly report at international conferences. "Special emphasis in our immediate plans is put on the ultrafast dynamics in ferroics project as it allows us to develop laboratories and actively cooperate with leading Russian and international research groups, exchange experience in promoting the research and educational activities", N.Sherstuk says.