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This research investigates complex studies of electrical conductivity and magnetoresistance of both strain and non-strain samples of p-type Si whiskers with different degrees of doping with boron and nickel in a wide temperature range from 4.2 to 300 K. It is established that the greatest manifestation of the piezoresistive effect is observed in the vicinity of concentrations which correspond to the metal-insulator transition. Investigation of the magnetoresistance of crystals was carried out in the range of fields with induction up to 14 T. Whiskers of silicon with a doping concentration of boron of 5•1018 cm-3 can be used as a sensitive element for two-functional deformation and magnetic field sensors in difficult operating conditions. Microwires for research were grown by chemical transport reactions with the crystallographic orientation and with the concentration of charge carriers, which corresponds to the vicinity of metal-insulator transition (5•1018 cm-3). The nickel doping was conducted by the low-temperature diffusion from the precipitated film on the surface of the crystal. The uniaxial strain of Si microcrystals was carried out by fixing them on substrates with the different coefficient of thermal. The metallic-type temperature dependence on the resistivity is typical for heavily doped silicon microcrystals (with the bor concentration >5•1018 cm-3) for both deformed and non deformed samples. Significant influence of the deformation on characteristics of microcrystals wasn't found. The maximum magnetoresistance of such samples doesn't exceed 4% in magnetic fields with induction of 14 T at the temperature of liquefied helium. The resistivity of Si crystals with ρ300K = 0.012 Ohm•cm (which corresponds to the dielectric side of MIT) is reduced in several times at the temperature of liquefied helium and under the uniaxial deformation. Decreasing of boron concentration reduces this effect. This is also confirmed by the calculation of the experimental data temperature dependence of gauge factor for these samples in helium temperatures. The gauge factor is K4.2K=165 at the compressive strain ε=–5.29•10-3 RVUs. It is also found that the deformation of these samples has significant impact on characteristics of the magnetoresistance and the value of the magnetoresistance decreased almost in 3 times. The undeformed samples of Si p-type microwire doped with nickel and boron concentration in the vicinity of dielectric side to MIT can be used as the sensing element of magnetic field. The significant magnetic field dependence on magnetoresistance is observed in such crystals which can reach a value of 250% at 14 T.

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.

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 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.

Was observed frequency dependence of active resistance of silicon nanowires in the vicinity to met from the dielectric side of metal-insulator transition. The characteristic data in wide temperature range has been analysed for processing information about specific mechanism charge carriers displacement at low frequency and it is in good arrangement with theory.