Semiconductor high sensitivity sensors

The head of the laboratory is Ramizulla Abdullaevich Muminov - Academician of the Academy of Sciences of Uzbekistan, Corresponding Member of the Russian Academy of Technological Sciences, Doctor of Physical and Mathematical Sciences, Professor, twice Winner of the State Prize of the Republic of Uzbekistan in the field of science and technology.

The laboratory was organized in 1971 at the Physicotechnical Institute of the Academy of Sciences of Uzbekistan.

In the group Muminova R.A. At present, the laboratory team employs one academician, one doctor of science, as well as research workers (9) and engineering and technical personnel (6). - a total of 9 + 6 people.

Fundamental studies of physical processes in pin structures, which are the basic elements of semiconductor electronics, both in the mode of strong charge association of the base (i) area, and in the conditions of double injection, when a high concentration plasma fills (i) - the area had important scientific and practical importance . On the one hand, these studies opened up a new scientific direction - the study of hydrodynamic phenomena in a degenerate electron-hole plasma and made it possible to solve the problem of creating highly-point semiconductor lasers in the infrared range of a large-volume active region and, on the other hand, initiated a fundamentally new representation in the field of physics and technology of semiconductor detectors of nuclear radiation. The basis of this view is the experimentally established concept of a significant role in shaping the properties of the combined region and the functional characteristics of the detectors of fluctuations in the distribution of lattice defects, leading to the appearance of local inhomogeneities in the distribution of the electric field in the bulk of the crystal.

    The development of this direction will allow in the future to establish the physical nature and properties of local heterogeneities, to stimulate the creation of diagnostic methods for the selection and control of the source material. The group for the first time proposed and implemented a comprehensive study of the response of semiconductor materials and devices (detectors, solar cells, surface barrier and MIS structures) to external influences: a light, non-uniform strong pulsed magnetic field, ultrasonic fields. The result of research on the phenomena that occur in semiconductors under these conditions was the development of fundamentally new ways of conducting low-temperature diffusion and annealing, ways to eliminate defects in semiconductors and accelerate ion diffusion processes; ways to improve the spectrometric characteristics of detectors and the energy characteristics of solar cells. The physically important aspect of the developed direction is the theory of the occurrence of kinetic phenomena in semiconductors under conditions of acoustically stimulated nonequilibrium of thermal phonons. It allows a deeper and wider understanding of the mechanisms of formation of functional characteristics of semiconductor devices in ultrasonic fields and the specifics of the interaction of ultrasonic waves with lattice defects, to carry out a targeted change in the defective structure of semiconductor materials, and also opens up prospects for creating highly sensitive devices using battery effects. As a result, the group solved the tasks of creating semiconductor nuclear radiation detectors of various purposes on the basis of domestic industrial silicon with operational characteristics at the level of world standards. These are detectors with a lengthy sensitive area from 5 μm to hundreds of μm, and from 1 mm to 10 mm, and also shows ways to obtain detectors, a sensitive area of ​​tens of mm on a physical basis of the exclusive phenomenon in semiconductor structures. Based on the results of these studies, the production of a small series of semiconductor nuclear radiation detectors for various applications was launched at the Physics - Sun NGO. They, according to experts, have characteristics at the level of world standards and are widely used in research onboard spacecraft, on installations of the Tacomak and Dolphin types, on accelerators in the city of Serpukhov, Dubna, Alma-Ata, as well as in a number of other scientific experiments, special equipment. Developed detectors were repeatedly awarded gold, silver and bronze medals at various exhibitions.

In the last 15-20 years, the main areas of research work of the group Muminova R.A. There are two areas of science and technology:

1) Design and manufacture of highly efficient silicon - lithium p-i-n detectors for large volumes of the sensitive area, as well as a sensitive surface. They can be used in science and technology, geology, environmental protection, medicine, etc.

2) Scientific - technical - technological research and development of new physical ways to increase the efficiency of silicon solar cells.

Using the achievements of nanophysics, (nanotechnology, holography, superlattices, etc.).

The main scientific, technical and technological results and achievements in the field of the subject of the first line of research:

According to chronology, all the most important scientific results are given (since the beginning of the 90s on the subject of detection)

(reports, Rajapov's thesis, publications, reports of recent years, etc.) mainly in English.

The main scientific, technical and technological results and achievements in the field of the second direction of research:

In chronology to bring important results from the reports on the subject of AOC.

Publications on the AOC are mainly in English.

Main results and today's topics:

The objects of research are both monocrystalline semiconductors - silicon and gallium arsenide, and polycrystalline films such as cadmium and bismuth telluride, as well as oxide layers in intergranular regions and on the surface of structural metals such as aluminum oxide (Al2-x O3 + x) and titanium oxide.

The focus is on those structural features of semiconductors on which the performance properties of sensors based on them depend, in particular sensors accumulated fatigue damage, as well as ionizing radiation sensors and optical quantities

In particular, it was found that the electrical structure of silicon having a resistivity in the region of 1 -: - 3 Kom * cm allows the manufacture of silicon-lithium ionizing radiation detectors that are not inferior in their properties to the corresponding Si (Li) detectors made of expensive pure silicon.

It was also established that when an ultrasonic wave is superimposed on a semiconductor or semiconductor structure, the structure of the lattice and the nature of its interaction with the electronic subsystem change, which for the frequencies and amplitudes found and at certain exposure durations leads to an improvement in the adhesion properties of contacts and operational properties of semiconductor solar cells [3 -five].

The laboratory staff improved the technology for producing semiconductor epitaxial layers based on gallium arsenide and its compounds. Field-effect transistors based on thermoelectric and photovoltaic effects, two-barrier and multilayer structures with an integrated hetero and metal-semiconductor area in the spectral range 0.4-1.6 μm, with a high internal gain and parameters exceeding the known analogues have been developed. Technological techniques for creating photovoltaic devices with a microrelief interface, distinguished by their resistance to radiation and temperature effects, are developed.

Fundamentally new is the approach to the development of sensors accumulated fatigue damage of structural materials. Here the main problem is the structural stability of the material. In the process of fatigue evolution, we cannot assume a given set of interacting units, or a certain set of transformations of these units. This means that the definition of a system must be modified in the course of evolution. This kind of evolution is associated with the concept of structural stability. We are talking about the reaction of a given system to the introduction of new units that can multiply and involve in the interaction various processes occurring in the system.

The problem of the stability of the system with respect to changes of this type comes down to the following. New components introduced in a small amount into the system lead to the emergence of a new network of reactions between its components. A new network of reactions begins to compete with the old way of functioning of the system. If the system is structurally stable with respect to the invasion of new units, then the new mode of operation is not established, and the new units themselves die. But if structural fluctuations successfully "take root" (for example, if new units reproduce quickly enough and manage to "capture" the system before they die), then the whole system is rebuilt into a new mode of operation: its activity is subject to the new "syntax".

Important in the evolutionary theory of fatigue is the resulting feedback between macroscopic structures and microscopic events: macroscopic structures, arising from microscopic events, should in turn lead to a change in microscopic mechanisms. Such interrelated processes give rise to very complex situations, and this circumstance must be recognized when starting to model them.

 Group of academician R.A. Muminov
The main directions of research of the group of Professor R. Muminov:
Fundamental principles of creating instrument semiconductor structures with various functional purposes being the main direction of research of the group of academician R. Muminov aimed at solving the following problems in semiconductor physics:

 

  • A model has been developed and a complete theory of a new contact structure, which has a needle-like geometry and functionally as a pn junction, is presented (that is, a nano-dimensional “pn junction” theory is developed).
  • A GaAs / AlGaAs heterophotoconverter based on GaP substrates with high thermal conductivity was developed. This heteroprotein converter is able to work in the range of solar radiation concentration Кс = 1 ... 100 in the mode of passive heat sink.
  • A technology is proposed for the formation of nano-inclusions based on silicon atoms on the surface of silicon single-crystal plates. This structure has a wider spectral sensitivity with respect to the traditional silicon photoconverter.
  • A theoretical model has been developed which describes the formation of a space charge region in fundamentally new contact structures consisting of a semiconductor base and nano-inclusions on its surface. It is shown that the specifics of a new type of contact is completely determined by the electrical capacity of nano-inclusions. A distinction has been established between the properties of a new type of contact, both in structure and length, from similar contact properties characteristic of Schottky barriers, continuous p – n junctions and heterojunctions.
  • The physical optimal conditions for the formation of a diffraction concentrator in the form of embossed diffraction gratings are determined. The features of their use as concentrating systems in solar cells based on gallium arsenide heterostructures are studied. It is shown that the use of diffraction and holographic concentrators are quite effective and they do not require an automatic tracking system for the Sun. All this creates new approaches for the widespread use of gallium arsenide solar cells.
  • A theory has been built and a mechanism has been established for the formation of a space charge region in fundamentally new contact structures consisting of a semiconductor base and nano-inclusions on its surface.
  • A theoretical model has been developed for the formation of a space charge region in fundamentally new contact structures consisting of a semiconductor base and nano-connections applied to it.
  • The differences in the properties of a new type of contact are determined, both in structure and in length with respect to similar contact phenomena characteristic of Schottky barriers, continuous pn-junctions and heterojunctions.
  • A theoretical model of a new contact structure has been developed that provides effective phototransformation in the wide infrared range of solar radiation. It is shown that the effective absorption of infrared radiation becomes possible due to the elongation of the space charge region, which is ensured by creating many nanoscale pn junctions directly on the substrate.
  • The methods for the formation of nanocrystalline silicon inclusions (nc-Si) in the dielectric matrix of silicon oxide SiO2 are studied. The method of creating nc-Si on the silicon surface is chosen, with the aim of increasing the efficiency of silicon solar cells.
  • The mechanisms for the formation of etching pores on the surface of a silicon wafer, the methods and modes of etching are studied in order to create a given concentration of pores and topology for further doping of the developed silicon surface, that is, creating a pn junction.
  • The possibility of the formation of nc-Si pp SiO2 on a developed silicon surface by diffusion from parallel sources is investigated. The influence of the distribution and concentration of impurities on the electrical properties of the pn junction is studied, and the possibility of controlling optical and electrical parameters, depending on the heat treatment condition, is shown.
  • Computer simulation has studied the optical and electrical properties of the nc-Si-SiO2 system. It is established that the effective optical constants of porous silicon strongly depend on the concentration and topology of the pores. Such a relationship makes it possible to create effective anti-reflective coatings for solar cells.
  • Nanostructural surface treatment of a semiconductor and the deposition of zero-dimensional nanoinclusions from another homogeneous semiconductor material on it leads to the appearance of quantum dots (QDs), that is, nano-inclusions with dimensions of 10 ÷ 40 nm. These nano-inclusions are identified as quantum dots, since their energy spectrum consists of a set of discrete levels, similar to that of a single atom. Quantum dots of high concentration on the sensitive surface of the FP contribute to the appearance of an additional concentration of e-d pairs in the process of converting solar radiation into electrical energy.
  • The analysis of scientific publications on the current state of the problem of increasing the efficiency of conversion of solar and thermal energy into electrical energy using solar cells and thermoelectric converters has been carried out.
  • For further research in the field of increasing the efficiency of solar energy conversion into electrical and thermal energy, taking into account the widespread use of photo-and thermoelectric converters in photo-energy, as well as the availability of manufacturing technology as objects, silicon-based solar cells and thermoelectric converters based on bismuth systems were used -tellurium.
  • The design of a combined installation for the conversion of solar radiation, consisting of solar cells and thermoelements, is proposed. The results of measurements of parameters of the combined installation based on photovoltaic cells from crystalline silicon and thermoelements of the bismuth-tellurium system are presented. It is shown that the combined installation increases the conversion efficiency of solar radiation by 5% and such installations can be operated in countries with very hot climates.
  • A laboratory sample of a combined system — a phototransducer, a thermoelectric converter based on silicon SCs and bismuth – tellurium thermal converters — was developed and manufactured. The possibility of increasing the efficiency of the combined system by 5% compared with a photovoltaic battery is shown.