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Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering

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No 1 (2014)
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https://doi.org/10.17073/1609-3577-2014-1

MATERIALS SCIENCE AND TECHNOLOGY. SEMICONDUCTORS

4-7 813
Abstract

In this paper, heterostructures with self−organized quantum dots have been produced using incongruent evaporation. Island films on the basis of the intermediate phases forming in the Sn-Se have been grown. The surface morphology of the structures has been studied using atomic force microscopy (AFM). A certain change of the band gap confirms the presence of quantum states in the electron spectrum of the structures. We have found that for obtaining structures with a homogeneous distribution of islands the process of incongruent evaporation should be carried out at high condensate selection speeds. By varying the speed of incongruent evaporation of the film material one can achieve directed growth of islet films with a preset islet size distribution.

8-12 980
Abstract

Through three−layered structure has been formed on silicon wafers 500 microns thick by electrochemical etching in a solution of hydrofluoric acid without using additional deletions monocrystalline layers. The resulting structures are divided into two types. The first type pass−through structure comprises two outermost macroporous silicon layers 220—247,5 microns thick with a pore diameter 7—10 microns and an average mesoporous silica layer 5—60 microns thick with a pore diameter of 100—150 nm. The second type pass−through structure includes macroporous silicon layer 250 microns in thickness, interlocking in the depth of the silicon wafer to form a cavity the size of 4—8 microns. The developed technology will allow forming monolithic structures of membrane−electrode assembly microfuel elements in an easier and more reliable manner.

MATERIALS SCIENCE AND TECHNOLOGY. DIELECTRICS

13-16 896
Abstract

This paper reports results on the effect of Sr impurity on damage of crystalline potassium chloride under exposure to laser irradiation. The experimental data are accounted for using the photochemical model of laser damaging. We assume that the light scattering impurity centers are in the form of large aggregates of impurity/vacancy dipoles. The state of the impurity was monitored using light scattering. Under laser irradiation, photochemical reactions occur in the impurity centers, and the accumulating products of these reactions damage the crystals. We have found a correlation between the concentration of the impurity in the equilibrium impurity aggregates and the concentration of the damage initiating centers. We show that laser irradiation produces anion vacancies in impurity agglomeration areas and causes accumulation of F centers followed by the formation of colloidal quasimetallic particles on which specimen breakdown occurs. EPR spectroscopy revealed colloidal particles having quasimetallic properties.

17-23 1074
Abstract

Based on the concept of polymeric−polymorphous structure of glass and glassforming liquid (Minaev, 1987) experimental data have been analyzed revealing the nature of glass aging. We show that the glass forming substance is a copolymer consisting of structural nano-fragments (polymorphoids) in different polymorphous modifications (PM) of the material having no translational symmetry (long-range order). The study revealed that the process and degree of glass aging influences the properties of glasses, including a change in enthalpy, manifested in the exothermic and endothermic effects observed in thermograms of differential scanning calorimetry of heated and cooled glasses. We have shown that the physicochemical essence of aging is the transformation of polymorphoids from high−temperature PM (HTPM) into low−temperature PM (LTPM) which results, under certain conditions, in LTPM crystallization.

EPITAXIAL LAYERS AND MULTILAYERED COMPOSITIONS

24-31 991
Abstract

The equation connecting the misfit parameter f, the number of misfit dislocation (MD) families and the distances between MDs of the same family with the edge Burgers vector components taken for different dislocation families is obtained for the first time. It is valid for various interface boundaries (hkl). To get the equation, the long range normal and shear stresses associated with MD distribution have been considered. The optimum and non−optimum stress releasing processes are discussed. The problem of threading dislocation density diminution with generation of intersecting MDs with the same Burgers vector (L−shape MDs) is also considered for (001) and (111) interfaces. It is shown that such type MDs grow the level of the long range shear stresses and can be effectively generated only at an early stage of relaxation.

31-36 939
Abstract

The formation and self−organization of porous silicon (por-Si) surface mosaic structure at long anodic etching of p-type conductivity Si (100) (p-Si) in electrolytes with an internal power source has been considered. We show that the formation of 3D islets of mosaic structure nanocrystallites of por-Si occurs with the participation of the adsorbed deposited silicon atoms formed as a result of disproportioning reactions at etching of silicon single crystals, as is the case for epitaxial growth of nanocrystallites with molecular beam deposition of silicon atoms on А3В5 and Si semiconductor surface and their further spontaneous self−organization. We note the significant role of oxidation of the silicon surface in the formation and self−organization of a mosaic structure of por-Si during long-term anodic etching of p-Si (100) in HF : H2O2 electrolyte quantum−size and effects occurring in local areas of atomic rough surfaces real crystal silicon.

37-41 5310
Abstract

An increase of the critical current density in the second generation high−temperature superconducting wires (2G HTS) is the major challenge for researchers and manufacturers of 2G HTS wires all over the world. We proposed a new approach to increasing the number of percolation paths for superconducting current, i.e. increasing the number of low angle grain boundaries (<5°) in the epitaxial superconducting YBCO layer by magnetic structural processing (MSP) of buffer layers. New experimental results have been presented on the application of MSP for improving the structure and increase the texture sharpness of buffer in electrical conducting element of 2G HTS wire. The influence of MCO on the structural and textural properties has been investigated in a buffer consisting of epitaxial films of cerium oxide СеО2 and lanthanum zirconate La2Zr2O7 in the СеО2/4La2Zr2O7

architecture. The influence of the magnetic processing of the epitaxial La2Zr2O7 buffer film on the shape of grains has been found. A study under an atomic force microscope has shown that after magnetic processing the shape of grains improved significantly. A multilayer CeO2/4La2Zr2O7 buffer each layer of which was processed in a magnetic field, has a high degree of orientation: only one diffraction peak with (200) indexes is observed in the X-ray spectrum. X-ray settings of diffraction peak (200) indicate a well developed epitaxial structure of CeO2 and La2Zr2O7 layers. The texture of the buffer is by more than two degrees sharper than that of the Ni−5 at.% W substrate.

PHYSICAL CHARACTERISTICS AND THEIR STUDY

42-46 1215
Abstract

p+-n-Diodes have been studied. The diodes were manufactured on wafers (thickness 460 μm, (111) plane) of uniformly phosphorus doped float–zone–grown single–crystal silicon. The resistivity of silicon was 90 Ohm · cm and the phosphorus concentration was 5 · 1013 cm–3. The diodes were irradiated with 250 MeV krypton ions. The irradiation fluence was 108 cm–2. Deep–level transient spectroscopy (DLTS) was used to examine the defects induced by high energy krypton ion implantation. The DLTS spectra were recorded at a frequency of 1 MHz in the 78—290 K temperature range. The capacity–voltage characteristics have been measured at a reverse bias voltage from 0 to –19 V at a frequency of 1 MHz. We show that the main irradiation–induced defects are A–centers and divacancies. The behavior of DLTS spectra in the 150—260 K temperature range depends essentially on the emission voltage Ue. The variation of Ue allows us to separate the contributions of different defects into the DLTS spectrum in the 150—260 K temperature range. We show that, in addition to A–centers and divacancies, irradiation produces multivacancy complexes with the energy level Et = Ec – (0.5 ± 0.02) eV and an electron capture cross section of ~4 · 10–13 cm2.

47-52 831
Abstract

The efficient method of determining thermal parameters in high-power field-effect transistors has been developed and tested based on a study of transient processes during self heating by direct current. With the developed relaxation spectrometer of thermal processes differential distribution profiles of thermal resistance of KP723G transistors have been investigated which were selected in accordance with the regimes of setting of their crystals. Thermal resistance spectra have been obtained from the analysis of time−dependent dynamic thermal impedance using a new non−destructive method of differential spectroscopy using higher order derivatives (order 3). We present both continuous (integral) and discrete spectra of the distribution of internal thermal resistance in the transistors and the value of the junction/case thermal resistance. Thermal characteristics of the KP723G transistors and their imported counterparts IRLZ44 and IRLB3036 have been determined. The method of determining the active area of devices has been developed and its decrease during heating has been shown. The proposed methodology is useful in solving technological problems of forming the setting layers of crystals and intermediate layers between a crystal and a heat sink and also for the development of thermal models in SPICE modeling of powerful MOSFETs and diode emitters.

53-57 696
Abstract

Flexural elastic deformations of single-crystal silicon have been studied using microspectral Raman scattering. Results are reported on nano-scaled sign-changing shifts of the main peak of the microspectral Raman scattering within the single-crystal silicon cantilever beam during exposure to flexural stress. The maximum value of Raman shift characteristic of the silicon peak 518 cm-1 at which elasticity still remains, has been found to be 8 cm−1 which corresponds to an applied deformation of 4 GPa. We report three-dimensional maps of the distribution of internal stresses at different levels of deformation up to irreversible changes and brittle fracture of the samples that clearly show compression and tension areas and an undeformed area. A qualitative explanation of the increase in the strength of the cantilever beam due to its small thickness (2 μm) has been provided that agrees with the predictions of real-world physical parameters obtained in SolidWorks software environment with the SimulationXpress module. We have defined the relative strain of the beam surface which was 2% and received a confirmation of changes in the silicon lattice parameter from 5.4307Е to 5.3195Е by the BFGS algorithm.

ATOMIC STRUCTURES AND METHODS OF STRUCTURAL INVESTIGATIONS

58-64 1104
Abstract

The structure of PSZ crystals has been studied as a function of the content of the stabilizing impurity (Y2O3) by X–ray diffraction, transmission electron microscopy (TEM) and atomic−force microscope (AFM). The hardness and fracture toughness have been measured by microindentation. The study has shown that PSZ crystals obtained by directional solidification of the melt consist of two tetragonal phases (t and t’) with varying degrees of tetragonality. Increasing the stabilizing impurity concentration leads to an increase in the volume fraction of the “untransformable” t’ phase. Experiments have shown that an increase in the concentration of the stabilizing impurity leads to a growth in the amount of positively charged oxygen vacancies (the F++–centers) which increase the lattice parameter and stabilize the structure. The character of the twinned structure changes depending on the concentration of the stabilizing impurity. In PSZ crystals with Y2O3 concentration from 2.8 to 3.2 mol. % twins first, second and third orders as well as large twins consist of smaller twin domains are observed. At high concentrations of stabilizing impurities (3.7—4.0 mol. %) the twin structure becomes smaller and more uniform. This suggests that twinning occurs simultaneously and is localized within small volumes. The character of the twinned structure changes depending on the concentration of the stabilizing impurity. This work shows that the quantity of hardening (fracture toughness) is proportional to the content of the transformable t phase.

GENERAL ISSUES

67-75 1028
Abstract

The paper presents a wide range of problems associated with the formation, development and practical implementation of research in materials science, carried out under direct leadership of Academician F. A. Kuznetsov by the team of researchers from the Nikolaev Institute of Inorganic Chemistry SB RAS. It shows the fruitfulness of his ideas of complex physicochemical research into each stage of the preparation of material from the precursor to the finished specific device element. Attention is drawn to his accurate prediction of the importance of selectable objects of study, his ability to correlate ongoing research with urgent global issues such as electronics, computer science, energy and photovoltaics and his skill to rally the team with a common idea and encourage active participation in the development of science both in Russia and internationally while remaining the main driving force of conducted advanced work. The paper is written in the memory of the eminent person, organizer of science, scientist and patriot whose work has always been focused on breakthrough technologies that ensure the prosperity and security of the Motherland.



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ISSN 1609-3577 (Print)
ISSN 2413-6387 (Online)