Aluminum nitride films have been synthesized by reactive magnetron sputtering on n-Si(100) substrates. AlN layers with thicknesses from 2 to 150 nm were obtained to establish a correlation between the structure of the films and their electrical conductivity. Electron microscopy revealed that the amorphous structure of the films passes to nanocrystalline one while moving away from the substrate surface. Films with thicknesses below 20 nm had a high conductivity: up to 10 (Ω cm)–1; with an increase in thickness the conductivity dropped to 10–7 (Ω cm)–1. The high conductivity of thin AlN layers is believed to be due to the high density of the boundaries of grains built-in into amorphous matrix.

Пленки нитрида алюминия синтезированы с помощью метода реактивного магнетронного напыления на кремниевых подложках n-Si (100). Слои AlN толщиной от 2 до 150 нм получены с целью установления корреляции между строением пленок и их электропроводностью. С помощью электронной микроскопии установлено, что по мере удаления от поверхности подложки аморфное строение пленки переходило к нанокристаллическому. Пленки с толщинами до 20 нм имели высокую проводимость до 10 (Ом·см)–1, при увеличении толщины проводимость резко падала до 10–7 (Ом·см)–1. Предполагается, что высокая проводимость тонких слоев AlN обусловлена высокой плотностью границ зерен, встроенных в аморфную матрицу.

В статье демонстрируется работа модели компактного калибровочного источника нейтронов, который может быть использован для калибровки и определения функции отклика детекторов темной материи и детекторов электронных антинейтрино. Рассматриваемый калибровочный источник нейтронов представляет собой комбинацию радионуклида \({}^{252}\) Cf, который испытывает спонтанное деление с образованием нейтронов, и оригинального кремниевого полупроводникового детектора. Последний обеспечивает временную привязку к моменту образования нейтронов путем регистрации сигналов от осколков деления.

Influence of the prolonged irradiation by fission products of 252Cf radionuclide on the operational parameters of silicon-lithium Si(Li) p-i-n detectors, Si surface barrier detectors and Si planar p+n detector was investigated. The obtained results revealed a linear shift of the fission fragment peaks positions towards the lower energies with increase of the irradiation dose for all investigated detectors. The rate of the peaks shift was found to depend strongly on the detector type and the strength of the electric field in the detectors active region, but not on the temperature of irradiation (room or liquid nitrogen temperature). Based on the obtained results, the possibility of integration of the investigated types of Si semiconductor detectors in a radionuclide neutron calibration source is considered.

Operation of a model of a compact neutron source that can be used to calibrate dark-matter and electron-antineutrino detectors and to determine their response functions is demonstrated. The calibration neutron source in question is a combination of the ^252 Cf radionuclide, which undergoes spontaneous fission, producing neutrons, and an original silicon semiconductor detector. The latter provides a time reference for the neutron-emission instant by recording signals from fission fragments.

We present a description of the originally developed ������-spectrometer consisting of two Si(Li)-detectors with sensitive area thickness above 8 mm and 4 ������-geometry. The full absorption spectrometer allows for direct measurements of ������-spectra, disregarding the corrections to response function induced by the electron backscattering from the crystal surface. In case of ������-spectra of transitions to the excited state of the daughter isotope additional 3 & DPRIME;BGO-detector is used in order to detect the ������-quanta in coincidence with the pair of Si(Li)-spectrometers.

Точное измерение бета-спектров всегда имело большое значение в некоторых фундаментальных физических задачах, включая физику нейтрино. В этой работе мы представляем результаты измерения спектра источника \({}^{144}\) Ce– \({}^{144}\) Pr, выполненного с помощью установок двух типов с точностью, которая была существенно увеличена по сравнению с предыдущими исследованиями. Корректность теоретической подгонки была проверена формой разрешенного бета-перехода \({}^{144}\) Pr (0 \({}^{-}\) ) \(\to{}^{144}\) Nd (1 \({}^{-}\) ).

Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a Ce-144-Pr-144 source with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the Pr-144 (0(-)) -> Nd-144 (1(-)) allowed beta transition.

Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a ^144 Ce– ^144 Pr source with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the ^144 Pr (0 ^- ) →^144 Nd (1 ^- ) allowed beta transition.

Deterioration of the operation parameters of Al/SiO2/p-type Si surface barrier detector upon irradiation with alpha-particles at room temperature was investigated. As a result of 40-days irradiation with a total fluence of 8*10^9 α-particles, an increase of α-peak FWHM from 70 keV to 100 keV was observed and explained by increase of the detector reverse current due to formation of a high concentration of near mid-gap defect levels. Performed CV measurements revealed the appearance of at least 6*10^12 cm-3 radiation-induced acceptors at the depths where according to the TRIM simulations the highest concentration of vacancy-interstitial pairs was created by the incoming α-particles. The studies carried out by current-DLTS technique allowed to associate the observed increase of the acceptor concentration with the near mid-gap acceptor level at EV+0.56 eV. This level can be apparently associated with V2O defects recognized previously to be responsible for the space charge sign inversion in the irradiated n-type Si detectors.

Deterioration of the operation parameters of p-type Si surface-barrier detector and Si(Li) p-i-n detector upon irradiation by alpha-particles was investigated. The detectors were irradiated at room temperature up to a total number of the registered α-particles N α equal to 6 × 10 9 . Prolonged irradiation has resulted in a deterioration of the detectors energy resolution ability and it was found that the increase of α-peaks broadening can be described by a linear function of N α with a slope Δσ/Δ N α ∼ (1.4–1.8) × 10 –9 keV/α for both detectors. Resolution deterioration was associated with the increase of the detectors leakage current, which proceeds linearly with the number of absorbed α-particles with the slope ΔI/Δ Nα ∼ (7-17) × 10 -17 A/α. The increase of the detectors reverse current was related with appearance of radiation-induced defect level at 0.56 eV above the valence band.

Precision β-spectra measurement always had a great importance in some fundamental physics problems including neutrino physics. Magnetic and electrostatic spectrometers have high resolution, but at the same time usage of such kinds of equipment involves the size and cost issues. Since electron mean free path at the energy of 3 MeV (which is basically the maximum energy of a β-transition for the long-lived nuclei) does not exceed 2 g/crn 2 , electron registration could be effectively performed with the solid state scintillators and semiconductors. A strong probability of backscattering from detector surface is present in case of semiconductor detectors and is dependent upon the detector material. Such problem can be solved with 4π geometry detector development, which fully covers the radioactive source and is able to register the backscattered electrons. In this work we present the newly developed technology of 4π geometry β-spectrometer based on two semiconductor detectors. This spectrometer was used for measurement of the 144 Ce - 144 Pr spectrum, that is the perspective anti-neutrino source due to endpoint energy at 3 MeV and can be used for the sterile neutrino search experiments. The form-factor parameters that were obtained are: C(W ) = 1 + (-0.02877 ± 0.00028)W + (-0.11722 ± 0.00297)W -1 . The measurement accuracy was sufficiently enhanced with respect to the previous results.

The shape of 210 Bi β-spectrum was measured using a spectrometer based on Si(Li) detectors with a 4π geometry. Full absorption spectrometer allows for a direct measurement of the β-spectra without using the electron backscattering corrections for the response function. The measured value of nuclear shape factor C(W)=1+(-0.4378±0.0072)W+ (0.0526±0.0021) W 2 is in agreement with the results of previous studies.

The response function of the recoil nuclei in detectors designed for detection of neutrinos or dark matter particles can be determined only through usage of a neutron source with a known energy spectrum. A possible solution for a compact neutron calibration source is a combination of a 252Cf neutron source and a semiconductor detector that detects fission fragments, and thus records the neutron emission moment. This work is devoted to the degradation study of the operating parameters for silicon semiconductor detectors irradiated by fission fragments of the nuclide of 252 Cf. Two types of Si detectors were under investigations - silicon-lithium Si(Li) p-i-n detectors and silicon surface barrier detectors. As a result of the measurements, the maximum permissible radiation doses for the correct operation of both types of detectors and the relation of the received radiation dose to the spectroscopic characteristics of the detectors were determined.

A 4π β spectrometer consists of two Si(Li) detectors with a sensitive region that is more than 8-mm thick. Using this total-absorption spectrometer it is possible to make a direct measurement of β spectra without correcting the response function for the electron backscattering from the crystal surface. The β spectra of transitions to the excited states of daughter nuclei have been measured using an additional 3'' BGO detector of γ rays, which is connected in coincidence with the pair of Si(Li) detectors.

Photoelectric properties of MIS tunnel diodes produced on high-resistive p-type silicon wafers with thin aluminium nitride AlN insulator layer and Pd or Al metal gate electrodes were investigated. It was found that synthesized AlN films possess a fixed positive charge, which leads to the creation of near-surface inversion layer in silicon substrate. The ratio of the photocurrent to the dark current K = Iph / Idark (on / off ratio) was found to depend on the gate electrode material, illumination intensity and the applied reverse bias. For studied MIS structures K ratio varied from 10 4 to 10 5 and was two orders of magnitude higher than that for the control MS structure without the insulator layer. High on / off ratio of such MIS structures with AlN tunnelling insulator promotes their application as an effective photodetectors in optoelectronics.

The precision measurement of beta-spectrum shape for Bi-210 (historically RaE) has been performed with a spectrometer based on semiconductor Si(Li) detector. This first forbidden nonunique transition has the transition form factor strongly deviated from unity, and knowledge of its spectrum would play an important role in low-background physics in the presence of Pb-210 background. The measured transition formfactor could be approximated as C(W ) = 1 + (-0.4470 +/- 0.0013)W + (0.0552 +/- 0.0004)W-2, that is in good agreement with previous studies and has significantly increased parameter precision.