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In this study, to obtain frontal functional nanolayers of solar cells, an analysis of existing models of PSi was made. In order to achieve a low integral reflection coefficient of a textured Si sur...

The temperature dependences of resistance of n-type conductivity Bi2Se3 whiskers with doping concentration (1–2)⋅1019 cm−3 were studied in the temperature range 1.6–300 K. The sharp drop of the resistance was detected that is a result of a partial transition to the superconductive state at the critical temperature Tc = 5.3 K and probably due to the inclusion of β-PdBi2 phase in the studied samples. The transverse magnetoresistance of Bi2Se3 whiskers with various concentration of Pd doping impurity corresponding to the metal side of metal-insulator transition was studied in a magnetic field of 0–10 T. Superconductivity suppression effect by the magnetic field was found that permits to create the basic parameters such as the upper critical field Bc2 = 1.5 T, the coherence length of the superconductor ξ (0) = 15 nm and the superconducting gap Δ ≈ 0.8 meV. Studies of the n-type conductivity Bi2Se3 whiskers allow to create on their basis magnetic field sensors with a sensitivity of about 3.5% / T, capable in the temperature range of 4.2–77 K. The investigated crystals can also be used in the magnetic switch-control sensors magnetic switches due to the transition to the superconducting state at the critical temperature Tc, depending on a magnetic field induction.

The work is based on research magnetotoconductance polysilicon layer in SemOI-structures, which are under the influence of a magnetic field up to 14 T at temperatures of liquefied helium. The samples were subjected to deformation to determine the effect of material dispersion on low-temperature conductivity. Considered occurrence from capacitive relative magnetic conductivity at liquefied helium temperatures is caused by superposition of charge carriers at low temperatures in magnetic fields with B cr ~ 3T in the framework of the quantum transfer mechanism model. The determined concentration of polysilicon samples must be used in the development of sensors of mechanical quantities, operational in difficult operating conditions, namely under the influence of deformation in strong magnetic fields up to 14T at temperatures of 4.2 K.

The measurements of the magnetoresistance for p-type poly-Si with concentration 2.4 × 1018 cm−3 were carried out in the low temperature range 4.2–20 K and in the magnetic field up to 14 T. The results showed the presence of a negative magnetoresistance in polycrystalline silicon films in SemOI-structures. The low-temperature transport of charge carriers in p-type polycrystalline silicon films was considered within the framework of hopping conductivity and can be described by the spin–orbital interaction in the theory of weak localization. The calculated values of the coherence phase length 3–4 nm and the spin–orbit coherence length 30–50 nm at low temperatures 4.2–30 K correlate with parameters of hopping conductance and grain size, respectively, which show a contribution of Rashba spin–orbit interaction with energy ΔSO = 1.6 meV in the conductance not only inside the grains, but also its surface and between grain boundaries of polycrystalline silicon in SemOI structures.

Strain influence on the longitudinal magnetoresistance for the n-type conductivity InSb whiskers doped by Sn to concentration 6·10¹⁶–6·10¹⁷ сm⁻³ was studied in the temperature range 4.2–40 K and magnetic field up to 10 T. The Shubnikov–de Haas oscillations at low temperatures were observed in the strained and unstrained samples in all range of doping concentrations and magnetic fields. The character of longitudinal magnetoresistance dependences was analyzed and compared with theoretical one. The whisker magnetoresistance alters its sign with increasing magnetic field. It is positive at weak magnetic fields and becomes negative at higher magnetic fields. Possible mechanism of the large value of negative magnetoresistance (NMR) was discussed in the InSb whiskers with doping concentration in the vicinity to metal–insulator transition. The origin of large NMR was explained by the existence of classical size effect and boundary scattering during conductance in subsurface whisker layers. На основі досліджень поздовжнього магнітоопору ниткоподібних кристалів InSb n-типу провідності, легованих Sn до концентрацій 6·10¹⁶–6·10¹⁷ см⁻³ , в інтервалі температур 4,2– 40 К і магнітних полів до 10 Тл виявлено осциляції Шубнікова–де Гааза в деформованих і недеформованих зразках. Проведено аналіз поведінки польових залежностей магнітоопору згідно відомих теоретичних уявлень. Встановлено, що з підвищенням індукції магнітного поля магнітоопір ниткоподібних кристалів InSb змінює свій знак від позитивного до від’ємного. Обговорюються механізми, які зумовлюють появу високих значень від’ємного магнітоопору (ВМО) у зразках InSb з концентрацією легуючої домішки, що відповідає близькості до переходу метал–діелектрик. Існування ВМО пов’язане з класичним розмірним ефектом, а також гранічним розсіюванням у провідності приповерхневих шарів мікрокристалів. На основе исследований продольного магнитосопротивления нитевидных кристаллов InSb n-типа проводимости, легированных Sn до концентраций 6·10¹⁶–6·10¹⁷ см⁻³ , в интервале температур 4,2–40 К и магнитных полей до 10 Тл обнаружены осцилляции Шубникова–де Гааза в деформированных и недеформированных образцах. Проведен анализ поведения полевых зависимостей магнитосопротивления согласно известным теоретическим представлениям. Установлено, что с повышением индукции магнитного поля магнитосопротивление нитевидных кристаллов InSb меняет свой знак от положительного к отрицательному. Обсуждаются механизмы, которые обусловливают появление высоких значений отрицательного магнитосопротивления (ОМС) в образцах InSb с концентрацией легирующей примеси, соответствующей близости к переходу металл–диэлектрик. Существование ОМС обусловлено классическим размерным эффектом, а также граничным рассеиванием в проводимости приповерхностных слоев микрокристаллов.

The transverse and longitudinal magnetoresistances of GaSb microcrystals with tellurium doping concentration of 1.7 × 1017 cm−3 under the influence of uniaxial compression strain were studied in high magnetic fields of 0–14 T. Low-temperature Shubnikov–de Haas oscillations were observed for unstrained and strained n-type conductivity GaSb microcrystals in the whole range of the magnetic fields. The magnetoresistance oscillation amplitude decreases with the temperature increasing in the range of 4.2–30 K. The Shubnikov–de Haas oscillation period was changed due to the strain influence, and it was found to be 0.039 T−1. The emergence of the splitting at a magnetic field of about 7 T was revealed in the longitudinal magnetoresistance of GaSb microcrystals doped to a concentration in the vicinity of the metal–insulator transition. The value of the g-factor was found in the strained samples, and it has a value of 53. The strain influence on the effective mass of the electron mc and the Dingle temperature TD were also studied. The appearance of the Berry phase caused by the strain was revealed in GaSb microcrystals allowing their transition to the topological insulator state.

Application of the porous silicon multitextures as an efficient and commercially viable coating has to be maximally adapted to processes of the silicon solar cell manufacturing. The possibility to create the porous silicon multitexture as a basic material for the fabrication of efficient solar cells is shown. As a result of electrochemical etching, the columnar porous silicon texture was fabricated in terms to obtain a low-reflection structure. The reflection of prepared frontal texture based on columnar porous texture exhibited lower values in comparison to the random pyramid texture in the wavelength range 400–1150 nm. It was demonstrated higher photovoltaic performances of test solar cells with a columnar porous silicon texture in comparison to those with pyramidal textures.

Giant magnetoresistance (up to 700%) of the deformed InSb whiskers with doping concentration 6×1016-2×l017 cm−3 was observed in magnetic fields with induction up to 10 T at temperature range 4.2–70 K. The effect was explained taking into account two-channel conductivity of the whiskers with core-shell structure. Besides, the obtained results were discussed in the framework of the quantum magnetoresistance theory. The obtained results allow to design the magnetic field sensor on the deformed InSb whiskers.

The paper proposes a comprehensive approach for the investigation of polycrystalline layers of SemOI- structures in a wide range of concentrations of dopant from 2.4×10−18 go 1.7×10−20 cm−3 for the temperature range 4.2-70 K by studying the frequency response in the frequency range from 0.010- 250 kHz and its analysis by the equivalent circuit method.

Development of a model of the solar cell (SC) structure for creating a mathematical algorithm of the efficiency of SC with porous silicon is shown. The mathematical apparatus of the universal structure of porous silicon-based SC has been shown. Two approaches to its work were combined conditionally. Application of the porous silicon textures as an efficient and commercially viable coating has to be maximally adapted to processes of the silicon solar cell manufacturing.

In this paper we demonstrate a controlled fabrication of vertically aligned silicon nanowires (Si NWs) on n-type (100)-oriented and p-type (111)-oriented Si wafers by metal-assisted chemical etching (MaCE) method. The etching of Si-wafer samples covered with Ag nanoparticles as catalyst agents was carried out in HF/H2O2/H2O solution of various volumetric ratios. We show that molar concentration of AgNO3, Ag-nanoparticles deposition time, and the etching time determine the shape and size of produced Si NWs. Vertically aligned tall Si NWs can be produced by immersing the n-Si(100) wafer with pre-deposited from AgNO3 [22mM]/HF [5M]-solution silver nanoparticles in the etchant HF/H2O2/H2O (4:1:4) for different time. When the duration of Ag-deposition increased from 15 to 30 s in a solution 22 mM AgNO3/5 M HF, the etching rate of Ag-loaded n-Si(100) samples was found to be the same (∼ 1.6 µm/min). For 120 s Ag-deposited samples, the etching rate decreased to 560 nm/min. So, the height and density of Si...

The transverse magnetoconductance of the n-type conductivity InSb whiskers doped by Sn to concentration 4.4 × 1016 ÷ 7.16 × 1017 cm−3 were studied in the temperature range 4.2 ÷ 70 K and weak magne...

Studies of polysilicon in a wide range of concentrations from 2.4 × 1018 to 1.7 × 1020 in temperature range 1.6–300 K and high magnetic fields up to 14Т were carried out in order to predict the characteristics of a material suitable for the creation of microelectronic sensors of physical values based on SemOI-structures. One of the advantages of SemOI-structures is the ability to receive layers with difference in resistivity in a wide range: several orders of magnitude. As it is determined by studies at low temperatures the transfer of charge carriers in polysilicon occurs due to hopping on localized impurities. There have also been found combined mechanisms of current flow at low temperatures, which, depending on the observation temperature, are evident in the transition from the Mott law to the percolation mechanism of Shklovskii-Efros. Those effects can be used to create elements of sensor technology. Sensors of thermal quantities for cryogenic temperatures were developed with TCR = − 9% × K−1 in the range of 4.2–50 K and mechanical quantities for cryogenic temperatures were developed for ultra-sensitivity with coefficient of gauge-factor K = 15500 in the range of 4.2–50 K. Investigation in wide range of cryogenic temperatures was conducted with the purpose of optimizing the geometry of the sensor membrane (its thickness and surface area) in order to obtain optimal stresses and deformations in the membrane. This process is essential for the sensor to be able to provide a sufficient amount of the output signal while maintaining the strength of the membrane and the sensor structure as a whole.

The conversion efficiency of solar energy can be significantly increased if silicon of a multiporous texture is used as the front surface of a solar cell. The possibility to create the porous silicon multitexture as a basic material for fabrication of efficient photoelectric converters is shown. As a result of electrochemical etching, the columnar porous silicon texture was fabricated in terms to obtain a low-reflection structure. The reflection of prepared frontal texure based on columnar porous texure exhibited lower values in comarison to random pyramid texture in the wavelength range 400-1150 nm. It was demonstrated higher photovoltaic performances of test photoelectric converters with a columnar porous silicon texture in comparison to those with pyramidal textures.

An influence of a magnetic impurity distribution on the AC transport of charge carriers in silicon whiskers doped with boron and nickel at low temperatures was investigated. The concentration of Ni impurities obtained from impedance and magnetization data was shown to coincide and equal to 3×1017 cm−3. The obtained hysteresis of the whisker magnetization was used to design multifunctional sensor as well as storage device.

The article deals with the studies of strain influence of n-type GaSb whiskers magnetoresistance at low temperatures 4.2 – 60 K The crossover from WAL to WL occurs under the compressive strain at 4.2 K The field dependency of the whiskers magnetoresistance was used for design of sensor of magnetic field induction in the range 1-11 T.

In this paper the results of micromachining of Si wafer by various approaches are presented. The technological process based on silicon-on-insulator technology (SOI) was developed. It was shown that by choosing the topological size of the grooves, cavities and their shape, it is possible to obtain the cavities underneath the surface of Si wafer. The next procedures of deposition of polysilicon and silicon oxide films allowed to fabricate the sealed SOI cavities, which were considered as the device structures, sensitive or actuator elements. The process of Si-nanostructure fabrication through the wet chemical etching of Si wafer applicable in a wide range of applications is presented.

Germanium whiskers with gallium concentration $2\times 10^{17}\mathrm {c}\mathrm {m}^{-3}$ were chosen to investigate magnetoconductance in the range 0-14 T at 4.2 K under compressive strain up to - $2\times 10^{-3}$ rel.un. Strain influence on spin-orbital splitting on the valence band spectrum was studied. As result, the splitting of light and heavy hole branches was found under compressive strain according to kp-method. The spin splitting energy $\Delta \mathrm {s}\mathrm {o}$ as well as Rashba cubic parameter $\beta \mathrm{so}$ was found due to studying the longitudinal magnetoconductance of Ge whiskers at low temperatures.

The basis of the research of this work is to predict the characteristics of sensors of the thermal quantities based on silicon whiskers admixture with B & Ni impurities. In these samples, the concentration of the transport impurity of boron corresponds to the phase transition of the metal-insulator in silicon from the metallic side. On the basis of experimental temperature dependences of resistance of microcrystals Si (B, Ni) with a concentration of boron NB≈l×1019 cm−3 and resistivity crystals P300k=0.007 Ohmxcm in the temperature range 4,2-300 K, the linear dependence of the resistance versus temperature with positive values of the temperature resistance coefficient is shown. Determined by the temperature of liquefied helium maximum magnetoresistance reaches no more than 4% in magnetic fields with induction do14T. Proposed thermoresistive sensor is working in harsh operating environment and is resistant to the influence of destabilizing factors.

The paper presents a new biosensor design for protein detection. An electric circuit is proposed on the basis results of technological and circuit-layout simulation of the biosensor. In this design, a capacitor, one side of which is a sensitive region, serially connected to the gate of the amplifier transistor. The simulation results show that the developed biosensor has a high sensitivity and linear dependence of the output voltage on the potential of the information signal.

The results of studies on fabrication of silicon nanowires on the surface of silicon wafers of different types using the metal-assisted chemical etching method are presented. The influence of the deposition time of Ag particles on their morphology and filling density on the surface of silicon wafers has been analyzed. At different etching time of wafer samples of n-type in a HF-H2O2 based etching solution, vertically aligned arrays of solid nanowires are obtained. It is shown that changing the duration of Ag nanoparticles deposition at the same etching time, it is possible to change the distance between the nanowire stacks. It was established that under identical technological conditions the nanowires were not formed on a p-Si wafer. The results are discussed from the point of view of the specific etching mechanism of Si wafers with different type of conductivity and crystallographic orientation.

Silicon whiskers with boron concentration 2×1018cm-3 were chosen to investigate magnetoconductance in the range 0–14 T at 4.2 K under compressive deformation up to -2×10-3 rel.un. Deformation influence on spin-orbital splitting on the valence band spectrum was studied. As result, the splitting of light and heavy hole branches was found under compressive deformation according to kp-method. The spin splitting energy Δ so was found due to studying the longitudinal magnetoconductance of Si whiskers at 4.2 K.

Магнітопровідність ниткоподібних кристалів Si з концентрацією легуючої домішки 2 x 1018 см – 3 досліджували в інтервалі магнітних полів 0-14 Тл при кріогенних температурах за деформації стиску до – 2 x 10 – 3 відн. од. Легування кристалів бором здійснювали у процесі росту методом хімічного парофазного осадження і концентрація носіїв заряду, згідно холлівських вимірювань, становила порядку 2 x 1018 см – 3. Одновісну деформацію ниткоподібних кристалів здійснювали шляхом їх закріплення на підкладках з використанням термічної деформації за рахунок різниці коефіцієнтів термічного розширення кристала і матеріалу підкладки. Досліджено поздовжній магнітоопір для недеформованих і деформованих зразків Si в інтервалі температур 4.2 ÷ 70 К. Недеформовані зразки мають квадратичну залежність магнітоопору від індукції магнітного поля. Деформація приводить до появи великого від’ємного магнітоопору з максимальною величиною до 15 %. Обговорюються можливі причини цього ефекту. Найбільш вірогідною причиною виникнення від’ємного магнітоопору є слабка локалізація носіїв заряду. Згідно з розрахунками у моделі слабкої локалізації носіїв заряду показано, що довжина когерентності Lφ і довжина спін-орбітальної взаємодії Lso пропорційна T– 0.53 і T – 0.45, відповідно, що відповідає теоретичним даним T– 1/2 для двовимірної системи. Це свідчить про те, що основний внесок у провідність ниткоподібних кристалів Si вносить транспорт носіїв заряду у приповерхневих шарах кристалів. Досліджено вплив деформації на спін-орбітальне розщеплення та спектр валентної зони ниткоподібних кристалів. В результаті розрахунків згідно k-p-методу виявлено значне розщеплення гілок легких і важких дірок під дією деформації стиску. Отримано енергію спін-орбітального розщеплення підзони важких дірок ∆SO, яка становить 1.8 меВ. Silicon whiskers with doping concentration of 2 × 1018 cm– 3 were chosen to investigate magnetoconductance in the range of 0-14 T at cryogenic temperatures under compressive strain up to – 2 × 10– 3 rel. un. The whiskers were doped with boron during the growth process by chemical vapor deposition method, and the concentration of charge carriers, according to Hall studies, was about 2 × 1018 cm– 3. The uniaxial strain of whiskers was carried out by fixing them to the substrates using thermal strain due to the difference between the coefficients of thermal expansion of the crystal and the substrate material. Longitudinal magnetoresistance for unstrained and strained Si whiskers was studied in the temperature range of 4.2 ÷ 70 K. The unstrained whiskers have a quadratic dependence of the magnetoresistance on the magnetic field induction. The strain leads to the appearance of negative magnetoresistance with sufficiently large magnitude (up to 15 %). The possible reasons of the effect were discussed. The most probable reason of negative magnetoresistance appearance is weak localization (WL) of the charge carriers. According to calculations within the WL model, the coherence length Lφ and spin-orbit length Lso are proportional to T− 0.53 and T− 0.45, respectively. The latter one is closed to T− 1/2 expected from the theoretical data for a twodimensional system. This fact is the evidence of the conclusion that conductance in Si whiskers mostly occurs in the subsurface layers of crystals. Strain influence on spin-orbit splitting and the valence band spectrum was studied. As a result, the splitting of light and heavy hole branches was found under compressive strain according to the k-p-method. The spin splitting energy for sub-band of heavy holes ∆SO was found to be 1.8 meV.

Negative magnetoresistance of InSb whiskers with different impurity concentrations 4.4 × 1016–7.16 × 1017 cm−3 was studied in longitudinal magnetic field 0–14 T in the temperature range 4.2–77 K. The negative magnetoresistance reaches about 50% for InSb whiskers with impurity concentration in the vicinity to the metal–insulator transition. The negative magnetoresistance decreases to 35 and 25% for crystals with Sn concentration from the metal and dielectric side of the transition. The longitudinal magnetoresistance twice crosses the axis of the magnetic field induction for the lightly doped crystals. The behavior of the negative magnetoresistance could be explained by the existence of classical size effect, in particular boundary scattering in the subsurface whisker layer.

This paper describes the method of metal assisted chemical etching (MacEtch) as an efficient approach for structuring the silicon surface with the ability to manage effectively the geometric parameters of the structures and their distribution on the surface of substrate. The surface texturing technology was presented and the structured silicon surfaces with regular and irregular types of surfaces have been obtained. This technology can be used for nanotexturing of the surface of silicon photovoltaic converters. The model of photovoltaic converter based on the crater-textured silicon surface with high efficiency was presented. Keywords: silicon nanostructures, photoelectric converter, meatl-asisted chemical etching.

The paper deals with obtaining of textured silicon surfaces by chemical etching. As a result of experiments based on the modification and optimization of obtaining a textured silicon, several methods of chemical texturing of the crystalline silicon surface were developed. It was shown that modified isotropic and anisotropic etching methods are applicable to create a microrelief on the surface of silicon substrate. These methods in addition to their high conversion efficiency can be used for both mono- and multicrystalline silicon which would ensure their industrial use.

This paper presents the device-technological simulation of local 3D SOI structures. These structures are created by use microcavities under surface of silicon wafer. Is shown that proposed microcavities could be use as a constructive material for CMOS transistor array on the bulk silicon and 3D SOI-CMOS transistor array, as well as the sensitive elements and their combinations. Such structures allow creation and monolithic integration the CMOS, SOI-CMOS circuits and sensitive elements for IC and SoC.

Study the magnetic properties of Si whiskers, the concentration of which corresponds to a dielectric and metal side of metal-insulator transition, is performed. Percolation laws of the magnetic clusters formation, that is important for development of spintronic devices, are considered.

In this study, we investigated strain-induced effects in p-type Si whiskers at low temperatures of 4.2–70 K in DC and AC currents. Si whiskers with boron concentrations close to the metal–insulator transition (MIT) were investigated. We determined the influence of strain (up to 5×10 –3 r.u.) on the active and reactive resistivity, thereby detecting inductive and capacity changes. We discuss the low temperature transport of charge carriers in Si boron-doped whiskers. The current was found to pass through the subsurface of the whiskers, which was accompanied by the capture and reemission of charge carriers by Tamm states. A high sensitivity sensor with a gauge factor of GF 4,2K ~15,000 is proposed for the measurement of strain at an AC frequency of 100 kHz at low temperatures, including T =4.2 K.

The study of the magnetoresistance in InSb whiskers with an impurity concentration in the vicinity to the metal-insulator phase transition, at low temperature range 4.2–77 K, and in fields , with induction up to 14 T , was conducted. The presence of Shubnikov-de Haas oscillations in both transverse and longitudinal magnetoresistance was observed. The following parameters of InSb whiskers were defined: period of oscillations 0.1 Т −1 , cyclotron effective mass of electrons m с ≈ 0.14 m о , concentration of charge carriers 2.3 × 10 17 сm −3 , g -factor g * ≈ 30 and Dingle temperature Т D = 14.5 K. To determine the nature of crystal defects, the electron scattering processes on the short-range potential, caused by interaction with polar and nonpolar optical phonons, piezoelectric and acoustic phonons, static strain centers and ionized impurities in n-InSb whiskers, with defect concentration 2.9 × 10 17 cm −3 , are considered. The temperature dependences of electron mobility in the range 4.2–500 K were calculated.

The effect of 8.6·1017 n/cm2 fast neutron irradiation on the magnetic susceptibility and magnetoresistance of Si whiskers with impurity concentration near metal–insulator transition (MIT) has been studied. Neutron irradiated specimens with boron concentration away of MIT are mainly diamagnetic with a small amount of paramagnetic centers originated from dangling bonds on the whisker surface. It has been established that at temperatures near 4.2 K, a significant contribution to the conductivity is made by light charge carriers of low concentration but with high mobility. The as grown whiskers with impurity concentration correspondent to MIT showed hysteresis loops in magnetization at temperature of liquid helium. Besides hysteresis loops in magnetoresistance was observed for whiskers under compression stress at low temperature up to 7 K. The possible reason of the effect can be magnetic interaction between impurities centers in subsurface region of the whisker with the orbital moment of dangle bounds in the whisker core–shell interstices.

Negative magnetoresistance of Si p-type whiskers with different impurity concentration $10^{18} - 5\times 10^{18}$ cm−3 which corresponds to the transition of a metal-dielectric in silicon and diluted with nickel were studied in longitudinal magnetic field 0–14 T in the temperature range 4.2–77 K. The large negative magnetoresistance values correspond to hopping conductance on the twice occupied by electrons impurity states. It is established that in order to predict the magnetoresistance of crystals, it is necessary to take into account the polarization component due to the nature of the hopping conductance at low temperatures

The architecture and topology of microsystem-on-chip for investigation of new structures and device elements is proposed. Realization of microsystem on silicon-on-insulator structures provides the small consumption of energy, increase fast-acting, radiation hardness and wide interval of working temperatures. The unified sensitive element is designed on silicon-on-insulator structures. The changes of informing signal parameters (capacities and/or resistance) are registered by circuits through the change of signal frequency of master supporting clock. The sensitive element has the regulated sensitivity and can be used for measuring of physical values of different type (of pressure, temperature, acceleration).

Temperature dependencies of the n-type conductivity Bi 2 Se 3 whiskers doped with palladium Pd dopant to the concentration of $(1\div 2)\times 10^{19}\text{cm}^{-3}$ which correspond to the metal side of the metal-insulator transition (MIT) were studied at low temperatures down to 1.5 K. The sharp drop was revealed on the temperature dependencies of the whiskers resistance at temperature of 5.3 K. The contribution of some effects as an electron localization, Kondo effect and the superconductivity were observed in the temperature range $1.5\div 77\text{K}$ . The magnetoresistance in the n-type conductivity Bi 2 Se 3 whiskers doped with different Pd concentration were measured in the magnetic field $0\div 10\text{T}$ and the same temperature range. The weak antilocalization model was considered as result of the magnetoconductance studies due to surface spin-orbit interaction in the n-type conductivity Bi 2 Se 3 whiskers.

In this paper a modified design of the MOS-transistor in the smart-sensors based on SOI-structure is proposed, in which the surface of the subchannel region is made in the form of a cylinder segment oriented along the drain-source areas of the transistor. The dependence of the drain current of such a transistor reaches almost 10−3 μA/μm from the voltage at the outlet at different voltage values at the gate, which is an order of magnitude higher than for similar operating conditions of traditional MON-transistors.

A sensitive element of a magnetic field sensor with a resistive principle of action was proposed using microcrystals of silicon doped with boron to a concentration of 5 × 1018 cm−3, which corresponds to the metal-insulator transition in silicon with a nickel layer formed on the crystal's surface, as well as the construction of a spin filter whose working capacity is due temperature mode below 100K. Sensitive elements of magnetic field — temperature sensors were created on the basis of microcrystals Si , working at cryogenic temperatures with a thermosensitive element for which temperature coefficient of resistance (TCR) = 20% × K−1. Developed a sensitive elements of magnetic field — deformations sensors with a strain-sensitive element for which K = 165 at a temperature of 4.2 K.

Piezoresistive properties of undoped and doped by tellurium to different concentration InSb thin layers were investigated in wide range of strain (e = ± 1.4 × 10−3 rel. un.). The value of gauge factor is the largest for undoped n-type InSb thin layers and layers doped by concentration of (4 ÷ 7) × 1016 cm−3. On the basis of such layers could be created strain gauges with high sensitivity. The n-type InSb thin layers under hydrostatic pressure up to 5000 bar were studied also. The coefficient of hydrostatic pressure is higher for undoped n-type InSb thin layers with majority concentration (2 + 3) × 1016 cm−3, it equals K h = (25 ÷ 27) × 10−5 bar−1. These layers are perspective materials to design high sensitive pressure sensors.

Experimental results on application of metal-assisted chemical etching (MACE) method for fabricating different morphologies on the surface of Si wafer, and the comparison of their optical properties in terms to develop structures with low reflectivity and high light absorption are presented. In order to obtain efficient anti-reflecting surfaces, Si nanowire arrays, and complex structures composed of micropyramids obtained by conventional alkali chemical etching and Si nanowires prepared by MACE method on the side faces of pyramids were produced on Si wafers. It was found that micropyramids textured by Si nanowires with an average diameter of 130 nm and 325 nm in height, show the highest absorbance (about 98%) and the lowest reflectance (less than 1%) values in the wavelength range 300-1100 nm. In comparison, the reflection of Si nanowire arrays prepared by MACE method was found to be 4%.

Currently, silicon and germanium, the most common materials in the production of discrete semiconductor devices and integrated circuits, do not always meet all the requirements to the sensing elements of mechanical quantities sensors. Therefore, it is logical to research the properties of other semiconductor materials that could be used as sensing elements in such sensors. A3B5 semiconductor compounds seem promising for such purpose. Effect of hydrostatic pressure up to 5000 bar on the resistance of n-type antimonide gallium whiskers doped by Se or Te was studied. Coefficient of hydrostatic pressure for this crystals was determined, it equals Kh = (16,5—20,0)•10–5 bar–1 at 20°N. Temperature dependence of resistance and coefficient Kh for this crystals in the temperature range ±60°N was studied. Design of the developed hydrostatic pressure sensor based on GaSb whiskers and its characteristics are presented. The possibility to decrease the temperature dependence of sensitive element resistance by mounting GaSb whiskers on the substrates fabricated from materials with different temperature coefficient of expansion was examined. It was shown that mounting of GaSb crystals on Cu substrate gives the optimal result, in this case the temperature coefficient decrease to 0,05%•°N–1, that leads to decrease of output temperature dependence. The main advantages of developed pressure sensor are: the simplified design in comparison with pressure sensors with strain gauges mounted on spring elements; the high sensitivity to pressure that is constant in the wide pressure range; the improvement of sensors metrological characteristics owing to hysteresis absence. The possible application fields of developed sensors are measuring of high and extremely high pressure, chemical and oil industries, measuring of pressure in oil bore-holes, investigation of explosive processes.

Silicon-on-insulator structures are an important material for modern microelectronic devices, in particular, for sensors of various physical values. As the electro-transport properties of such initially polycrystalline dispersed structures vary with the treatment of poly-silicon layer, this will determine, in particular, the device implementation of SOI at low temperatures. In this paper we report on extended AC and DC studies of low-temperature electrical conductivity of SOI-structures with initial boron concentrations in the vicinity to metal–insulator transition (2.4×1018 сm−3 and 4.8×1018 сm−3 for non-recrystallized and recrystallized samples, respectively) and its peculiarities at the influence of high magnetic fields. In particular, together with the results of DC studies of resistivity the observation of negative magnetoresistance at low magnetic fields imply the hopping conductivity of poly-silicon layers at low temperatures (ln ρ~Т−1/4). The study of the properties of poly-silicon layers in SOI structures by impedance analysis method (AC measurements) allowed for determining the effect of material dispersion on its low-temperature conductivity and for separating and identifying the contributions of various microstructure elements in the sample conductivity. In both the DC and AC cases the Mott law hopping conductivity in non-recrystallized poly-Si samples has been confirmed at cryogenic temperatures around liquid helium point. A capacitive type of Nyquist plot in turn supported this assumption. In laser-recrystallized poly-Si layers the charge carrier transport is limited by grain barriers and corresponds rather to percolation type of conduction, obeying the Shklovskii–Efros law.

The parallel and transverse magnetoresistance in InSb and GaSb whiskers doped with tin and tellurium, respectively, were investigated in the temperature range 4.2–77 K and magnetic field 0–14 T. Shubnikov-de Haas magnetoresistance oscillations were revealed at low temperatures for both semiconductor materials with impurity concentration near the metal-insulator transition. The following parameters of InSb and GaSb whiskers as oscillation periods, cyclotron effective mass of electrons, g-factor and Dingle temperature were defined.

Thermoelectric properties of Si1-xGex (x = 0.03) solid solution whiskers doped with B impurities to the concentrations 1017 – 1019 cm-3 were studied in temperature range 300 - 420K. An influence of the whisker morphology, in particular their diameters and obliquity, on Seebeck coefficient, thermal conductivity and resistance was investigated. Seebeck coefficient and resistance was shown to increase, while thermal conductivity to decrease when the whisker diameter drops from 100 to 10μm, that is accompanied by a rise of figure of merit (up to 0,12 at 300K). Use of the whiskers with large obliquity leads to a small rise (of about 10 – 15%) increase of their Seebeck coefficient.

The article deals with the influence of the magnetic impurities on magnetoresistance of silicon whiskers. The features of transition of the metal impurities (nickel) in silicon crystals are investigated. It is shown that the interaction between nickel impurities and the crystal lattice of silicon promotes the formation of magnetic conglomerates on the surface of the crystal. The polarized conglomerates (polarons) can influence the transport properties of the crystal. The temperature of the cluster formation in the range of cryogenic temperatures was also calculated. A comparative analysis of the magnetoresistance of unalloyed crystals and crystals with magnetic impurities showed that the nickel impurity has a significant effect on the magnetoresistance of the crystal. It is proved that these samples can be used as switches in microelectronics under the influence of both the magnetic field and the temperature below 150K.

Studies the effect of hydrostatic pressure on the indium antimonide thin films n- and p-type conductivity were carried out in the temperature range (−180 ÷ +100) °C. Temperature dependences of the resistance and hydrostatic pressure coefficient for sensitive elements based on InSb thin films doped with zinc and tellurium were studied. Obtained the high values of hydrostatic pressure coefficient and linear character its temperature dependence allows to suggest doped InSb thin films promising material for creating of the hydrostatic pressure sensors up to 5000 bar on their basis operating in the climatic temperature range.

This work pertains to the method for modification of silicon (Si) wafer morphology by metal-assisted chemical etching (MacEtch) technique suitable for fabrication of antireflective Si surfaces. For this purpose, we made different Au catalyst patterns on the surface of Si substrate. This modification allowed to obtain the close-packed Au nanodrop (ND) pattern that generates the nanowires (NWs) and the well-separated Au NDs, which induce the nanopore (NP) formation. The antireflective properties of these structures in comparison with NWs produced by the conventional Ag-MacEtch method were analysed. The total surface reflectance of 1~7% for SiNWs and ~17% for SiNPs was observed over the entire Si-absorbing region. Moreover, SiNWs prepared by Au-MacEtch demonstrate better antireflective properties in contrast to those formed by conventional Ag-assisted chemical etching. So, the use of SiNWs produced by the modified Au-MacEtch method as the antireflective material is favored over those prepared by Ag-MacEtch due to their higher light absorption and lower reflectance. The possible reason of these findings is discussed.

The magnetization and magnetoresistance of Si whiskers doped with to boron concentrations corresponding to the metal-insulator transition (2 × 1018 cm−3 ÷ 5 × 1018 cm−3) were measured at high magnetic fields up to 14 T in a wide temperature range 4.2–300 K. Hysteresis of the magnetic moment was observed for Si p-type whiskers with nickel impurity in a wide temperature range 4.2–300 K indicating a strong interaction between the Ni impurities and the possibility of a magnetic cluster creation. The introduction of Ni impurity in Si whiskers leads to appearance and increase of the magnitude of negative magnetoresistance up to 10% as well as to the decrease of the whisker resistivity in the range of hopping conductance at low temperatures. The abovementioned effects were explained in the framework of appearance of magnetic polarons leading to modification of the conductive channels in the subsurface layers of the whiskers.

Impedance spectroscopy studies for Si wires with dopant concentrations in the vicinity to metal–insulator transition in the low temperature range 4.2–70 K and frequencies 0.01–250 kHz have been conducted. The studies allowed us to determine the parameters of hopping conduction (localization radius, density of localized states, and average length of carrier hopping) in silicon whiskers and to compare them with theoretical data.

Polycrystalline silicon layers on the surface of oxidized silicon substrate, i.e. SOI-structures, with initial boron concentration (of about 2.4 × 1018 cm-3 ÷ 1.7 × 1020 cm-3) in the vicinity to metal-insulator transition have been investigated. Experimentally the AC performances for both non-recrystallized and recrystallized layers correlate with DC measurements. Conductivity caused by the hopping between localized states with energy magnitude close to the Fermi level, has a weak temperature dependence in the ranges where the Shklovskii-Efros law applies. In this case, the percolation type of charge carrier transport is observed. In contrast, the hopping conduction between localized states near the band edges has a strong temperature dependence, where the Mott law is obeyed. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The paper deals with investigation of silicon nanowires formation by LP CVD method on Si substrate using gold films as a mask. The average diameter of Si nanowires grown by LP CVD was about 60 nm. It was shown that using of Si-Au droplets as the mask allows to obtain vertically aligned silicon nanowires with average diameter of about 60 nm. The kinetics of radial and axial growth was investigated, the growth rates and kinetic coefficient of growth were calculated, which showed a good accordance to experimental data.

The low temperature studies of SOI-structures have been carried out in a temperature range of 4.2÷300K at magnetic fields up to 14T. The samples with initial boron concentration of about 2.41018сm-3 have been investigated. The results of the studies of SOI-structure conductance at low temperatures in the range of hopping conductance and a possibility to use this material in sensors are analyzed.