The mechanism of structure transformation in Cr/4H-SiC UV photodetectors, which is responsible for the cyclic gettering of radiation defects, under repeated proton irradiation, is proposed in this work.

An avalanche silicon photodiode has been developed for the near IR, visible, UV and VUV light ranges. The external quantum efficiency has been studied in the 114–170 and 210–1100 nm ranges. It has been demonstrated that the avalanche photodiode reaches the quantum yield of 29 to 9300 electrons/photon at the 160 nm wavelength and bias voltage of 190–303 V, respectively.

Electroluminescence has been studied in silicon light-emitting diodes containing oxygen precipitates at temperatures of 40-300 K. Oxygen ion implantation and multistage anneals are used for fabrication of the diodes. Over all temperature range, spectra are well approximated by one Lorentz and four Gaussian curves. Lines of dislocation-related luminescence D1-D4 (the D1 line is described by Lorentz curve) and oxygen precipitates (OPs) are present in the spectra. At temperature variation, peak positions of the D1, OP and D2 lines coincide with temperature dependence of the forbidden gap width reduced by values of 356, 330 and 303 meV respectively. Build and quenching areas are observed on temperature dependences of the electroluminescence intensities of the D1, OP and D2 lines, the activation energies of the processes are determined, and reasons of their appearance are discussed.

Abstract. The results of the effect of irradiation with Ar ions on the structural, electrophysical and optical characteristics of the ultraviolet Cr/4H-SiC photodetectors in the spectral range of 200−400 nm are presented. After a single irradiation with 53MeV Ar ions with a fluence of 1 · 1010 cm−2, the quantum efficiency of the photodetectors practically remained at the level of the initial samples due to the "gettering effect“ of simple radiation defects by cluster formations. The observed effect promoted a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a consequence, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After repeated irradiation of the photodetectors with Ar ions with a total fluence of 2 · 1010 cm−2, the decay of clusters was observed, the formation of a significant number of simple defect centers, which led to a decrease in the lifetime of current carriers and, as a consequence, to a decrease in photoconductivity of Cr/4H-SiC photodetectors.

Avalanche silicon photodiode have been developted for near ir, visible, UV and VUV light range. External quantum efficiency have been studied in 114 - 170 abd 210 - 1100nm range. It is demonstrated that photodiode reach from 29 to 9300 electrons/photon on 160 nm with bias voltage of 190 and 303 v respectively.

The results of the effect of irradiation with Ar ions on the structural, electrophysical, and optical characteristics of ultraviolet Cr/4H-SiC photodetectors in the spectral range 200 to 400 nm are presented. After a single irradiation with Ar ions with an energy of 53 MeV with a fluence of 1 × 1010 cm–2 the values of the quantum efficiency of photodetectors practically remain at the level of the initial samples due to the “gettering effect” of simple radiation defects by cluster formations. This effect contributes to a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a result, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After the repeated irradiation of photodetectors with Ar ions with a total fluence of 2 × 1010 cm–2 the decay of clusters and the formation of a significant number of simple defect centers are observed, which lead to a decrease in the lifetime of the current carriers and photoconductivity of Cr/4H-SiC detectors.

Abstract. The results of the effect of irradiation with Ar ions on the structural, electrophysical and optical characteristics of the ultraviolet Cr/4H-SiC photodetectors in the spectral range of 200−400 nm are presented. After a single irradiation with 53MeV Ar ions with a fluence of 1 · 1010 cm−2, the quantum efficiency of the photodetectors practically remained at the level of the initial samples due to the "gettering effect“ of simple radiation defects by cluster formations. The observed effect promoted a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a consequence, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After repeated irradiation of the photodetectors with Ar ions with a total fluence of 2 · 1010 cm−2, the decay of clusters was observed, the formation of a significant number of simple defect centers, which led to a decrease in the lifetime of current carriers and, as a consequence, to a decrease in photoconductivity of Cr/4H-SiC photodetectors.

Silicon light-emitting diodes with dislocation-related electroluminescence have been studied at room temperature. For the fabrication of the light-emitting diode structures, a well-known method for the formation of dislocation-related luminescence centers during anneals of silicon with a high oxygen concentration in a flow of argon was modified by introducing a preliminary O+- ion implantation and carrying out a final anneal in a chlorine-containing atmosphere. In the electroluminescence spectra, the D1 dislocation-related luminescence line dominates at currents less than 150 mA and the near-band-edge luminescence line starts to dominate with increasing current. The electroluminescence excitation efficiency for the D1 center is 3.3 · 10-20 cm2 · s at room temperature.

The possibility to increase the responsivity of 4H-SiC p+– n –n+ - photodiodes by varying the thickness of the p+ - epilayer has been studied. It is shown that the thinning of the upper epilayer by RIE with the use of metal contacts as a mask makes it possible to control both the maximum responsivity and the spectral dependence of the responsivity of photodiodes and does not lead to degradation of dark electrical characteristics.

Technical solution were presented for a foil spectrometer installed on the Globus-M2 and TUMAN-3M tokamaks for measuring the electron plasma temperature. Measurements have been carried out of the time dependence of the plasma temperature in the central region of tokamaks. Using of integrated photodetectors and unique beryllium foils with a thickness of 14–80 µm made it possible to increase the sensitivity of the spectrometer. An important quality of the foils used were the increased values of strength, plasticity, homogeneity, and the absence of surface and internal defects. The combined use of the spectrometer with Thomson scattering diagnostics made it possible to carry out regular temperature measurements in the Globus-M2 tokamak with a high spatial and temporal resolution. The influence of impurities is estimated on the measurement of the electron temperature of the plasma.

Abstract The paper presents the results of a study of the effect of irradiation with heavy Ar ions on the structural and optical characteristics of 4H-SiC. It has been shown that as a result of already single irradiation with Ar ions with an energy of 53 MeV with a fluence of 1٠1010 cm-2, at least 2 powerful local regions with negative deformation prevail in the structure of silicon carbide. Along with this, a region with positive deformation is also observed in the structure. The formation of localized clusters with negative and positive deformations, along with the undisturbed matrix, is accompanied by the formation of linear type defects that partially relieve stresses in the structure. It is assumed that the resulting complex defect structure upon irradiation with Ar ions provides the effect of gettering of point defects and leads to the quantum efficiency of 4H-SiC UV photodetectors at the level of the initial samples.

The external quantum yield of silicon avalanche photodiode in the wavelength range of 120-170 nm was performed. It was shown that the engineered avalanche photodiode has the external quantum yield of 24-150 electron/proton under reverse bias voltage of 230-345 V, respectively. The testing of worked out avalanche photodiode by means of pulse flash of 280 and 340 nm wavelength demonstrates the speed, corresponding to the bandwidth not less than 25 MHz.

A detector for detection of beta-decay electrons in experiments on recording of a signal of sterile neutrinos is searched for. A set of parameters indicates that an avalanche silicon precision detector is a promising detector that allows electron counting rates of up to 2.5 × 10 7 s –1 for an active area of 0.785 mm 2 at room temperature with a possibility of spectrometric detection.

We have designed a silicon avalanche photodiode for detecting vacuum ultraviolet radiation. The external quantum yield of a silicon avalanche photodiode has been investigated in the wavelength range of 120–170 nm. It is shown that the avalanche photodiode has an external quantum yield of 24–150 electrons/photons at a reverse bias voltage of 230–345 V. Testing of this avalanche photodiode with pulsed illumination at wavelengths of 280 and 340 nm has shown performance corresponding to a transmission band no narrower than 25 MHz.

Silicon light-emitting diodes with luminescence associated with (113) defects have been fabricated using implantation of 350 keV oxygen ions at the dose of 3.7∙1014 cm-2 and subsequent annealing at 700ᵒC for 1 h in a chlorine-containing atmosphere. Electroluminescence was studied in wide ranges of temperature and an excitation power. The line associated with (113) defects dominates in all the spectra. The temperature dependence of the line intensity depends on the excitation power in the range of low temperatures: an increase of the intensity with activation energy of 25 meV is observed at low current density and, with the increasing current density, a rise of the intensity is not observed. At higher temperatures, a decrease of the intensity with activation energy of 59 meV occurs regardless of a current density. With the increasing temperature, the peak of the line shifts by the same energy as the forbidden gap width, while the half width of the line grows linearly.

The results of a study into the effect of irradiation with heavy Ar ions on the structural and optical characteristics of 4H-SiC are presented. It is shown that even upon single-time irradiation with 53-MeV Ar ions at a fluence of 1 × 1010 cm–2 there are at least two powerful local regions with negative deformation dominant in the structure of silicon carbide. Also, a region with positive deformation is observed in the structure. The formation of localized clusters with negative and positive deformations along with the undisturbed matrix gives rise to linear-type defects that partially relieve stresses in the structure. It is assumed that, upon irradiation with Ar ions, the resulting complex defect structure provides the effect of point-defect gettering and leads to a quantum efficiency of 4H-SiC UV photodetectors that is comparable with that of the initial samples.

Silicon light-emitting diodes with luminescence associated with (113) defects are fabricated by the implantation of 350-keV oxygen ions at a dose of 3 . 7 × 10 14 cm –2 and subsequent annealing at 700°C for 1 h in a chlorine-containing atmosphere. The electroluminescence is studied in wide temperature and excitation-power ranges. The line associated with the (113) defects is dominant in all the spectra. The temperature dependence of the line intensity depends on the excitation power at low temperatures: an increase in the intensity with an activation energy of 25 meV is observed at low current densities and no rise in the intensity is observed with increasing current density. At higher temperatures, an intensity with an activation energy of 59 meV is quenched irrespective of the current density. With increasing temperature, the peak of the line of the (113) defect shifts by the same energy as the energy-gap width, whereas the half width of the line grows linearly.

Представлены результаты исследования различными методиками исходных структур n-4H-SiC, представляющих высоколегированную n+-подложку с выращенным химическим осаждением из газовой фазы эпитаксиальным слоем толщиной 5 мкм. Концентрация носителей заряда в эпитаксиальном слое в диапазоне Nd-Na=(1-50)·1014 см-3. Привлекая результаты рентгеноструктурного анализа, было установлено, что для получения эффективных 4H-SiC ультрафиолетовых фотоприемников желательно иметь структуры эпитаксиальных слоев, в которых наблюдается эффект геттерирования точечных дефектов, что приводит к росту времени жизни носителей заряда и увеличению значений квантовой эффективности. Фоточувствительность исследованных образцов значительно зависит от степени дефектности в CVD эпитаксиальном слое, приводящей к изменению времени жизни носителей заряда и, как следствие, к изменению квантовой эффективности 4H-SiC ультрафиолетовых фотоприемников. Ключевые слова: карбид кремния, рентгеноструктурный анализ, эффект геттерирования, квантовая эффективность.

Abstract The influence exerted by the carrier concentration in the range (1–50) × 10^14 cm^–3 in n -4 H -SiC chemical-vapor deposited (CVD) epitaxial layers on the spectral characteristics of UV photodetectors with Cr Schottky barriers in the range of 200–400 nm is revealed and explained in terms of the photoconductivity theory. Schottky barriers with a Cr film thickness of 20 nm and diameter of 8 mm are formed by thermal evaporation in vacuum through masks. A noticeable effect of the carrier concentration in the CVD epitaxial layers on the spectral characteristics of photodetectors upon heating to 200°C is also observed and accounted for by a difference between the generation-recombination processes. The irradiation of photodetectors with 15-MeV protons at a fluence of 4 × 10^12 cm^–2 and a temperature of 200°C leads to an increase in the quantum efficiency as compared to samples irradiated in similar modes at 25°C. This is indicative of an increase in the radiation hardness and service life of 4 H -SiC devices at elevated temperatures.