The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC integrated Schottky diodes (JBS) was studied for the first time in the operating temperature range Ti (23 and 175°C). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with Ub = 600 V, the fluence range was 5 × 1013–1 × 1014 cm–2; for devices with Ub = 1700 V, the fluence range was 3 × 1013–6 × 1013 cm–2. An increase in the irradiation temperature leads to a noticeable decrease in the effect of irradiation on the current–voltage characteristics of the diodes. The effect of annealing on the current-voltage characteristics of irradiated devices is studied.

The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC integrated Schottky diodes (JBS) was studied for the first time in the operating temperature range Ti (23 and 1750C). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with Ub = 600 V, the fluence range was 5×1013–1×1014 cm-2; for devices with Ub = 1700 V, the fluence range was 3×1013 – 6×1013 cm-2. An increase in the irradiation temperature leads to a noticeable decrease in the effect of irradiation on the current-voltage characteristics of the diodes. The effect of annealing on the current-voltage characteristics of irradiated devices is studied.

The effect of annealing on the parameters of 4H-SiC Schottky diodes irradiated with electrons at high temperatures has been studied for the first time. The electron energy was 0.9 MeV. The irradiation was carried out at temperatures of 23, 300, and 500oС at fluences  in the range 1×1016 – 1.3×1017 cm-2. The results of annealing after the irradiation at high temperatures are qualitatively different from the results of annealing after conventional irradiation at room temperature with the same fluencies. The results obtained indicate that the spectrum of radiation defects introduced into SiC under a high-temperature (“hot”) irradiation differs significantly from that of defects introduced by irradiation at room temperature. At irradiation temperatures of 300 and 500°C and large, the effect of "reverse annealing" was revealed, when the base resistance grows rather than falling as a result of annealing.

Впервые исследовано влияние облучения электронами с энергией 0.9 МэВ на параметры 4H-SiC диодов Шоттки с предельным блокирующим напряжением Ub=600 и 1700 В в диапазоне рабочих температур Ti (23 и 175oС). Диапазон флюенсов Phi составлял 1·1016-2·1016 см-2 для приборов c Ub=600 В и 5·1015-1.5·1016 cм-2 для приборов c Ub=1700 В. Облучение при комнатной температуре значительно увеличивает дифференциальное сопротивление базы диодов. Облучение теми же дозами при Ti=175oС --- предельной рабочей температуре приборов практически не сказывается на параметрах вольтамперных характеристик. Тем не менее DLTS-спектры демонстрируют значительное увеличение концентрации глубоких уровней в верхней половине запрещенной зоны не только после облучения при комнатной температуре, но и после облучения при Ti=175oС. Ключевые слова: карбид кремния, диоды Шоттки, электронное облучение, вольт-амперные характеристики, DLTS-спектры.

For the first time, the effect of irradiation at high temperature (“hot irradiation”) by protons on the capacitance – voltage and current – ​​voltage characteristics of silicon carbide based semiconductor devices was studied. We investigated commercial high-voltage (blocking voltage of 1700 V) integrated 4H-SiC Schottky diodes. Irradiation was carried out by protons with an energy of 15 MeV at temperatures of 20-400 ° C. It has been established that the most sensitive to radiation parameter determining the radiation resistance of devices is the ohmic resistance of the base, which increases monotonically with increasing radiation dose D. It is shown that during “hot” irradiation, the radiation resistance of diodes significantly exceeds the resistance of diodes in low-temperature (“cold”) irradiation . It was concluded that, with increasing irradiation temperature, the rate of formation of deep centers in the upper half of the band gap of silicon carbide decreases.

Исследовано изменение вольт-амперных характеристик и величины Nd-Na в базе диодов Шоттки и JBS-диодов на основе 4H-SiC при их облучении электронами с энергией О,9 МэВ и протонами с энергией 15 МэВП, показано, что исследованные диоды Шоттки сохраняли выпрямляющие вольт-амперные характеристики вплоть до доз облучения ~1О17 см-2. Установлено, что радиационная стойкость диодов Шоттки на основе SiC существенно превосходит радиационную стойкость кремниевых p-i-n-диодов с аналогичными напряжениями пробоя. Впервые исследовано влияние протонного облучения (энергия протонов 15 МэВ) на электрофизические и шумовые параметры 4H-SiC мощных вертикальных MOSFET.

AbstractIt is established experimentally that noticeable changes in the I – V characteristics and low-frequency noise in 4 H -SiC pin diodes irradiated by electrons with an energy of 0.9 MeV are observed after doses of Φ ≥ 1.4 × 10^15 cm^–2. The currents in the forward and reverse branches of the I – V characteristics vary nonmonotonically at voltages lower than 2 V with increasing dose, which is explained by the interaction between the excited electronic subsystem and metastable defects. In this case, a steady increase in the ideality factor and the series resistance of diodes in the region of exponential growth of the I – V characteristics at voltages exceeding 2 V is observed. The reliable operation of microwave devices with low-noise 4 H -SiC pin diodes under conditions of electron irradiation is possible up to a cumulative dose of Φ ≤ 10^15 cm^–2. In microwave devices, the level of low-frequency noise in which is irrelevant but the stabile regime of parameters is of importance, the dose can be increased to Φ ≈ 8 × 10^15 cm^–2.

The effect of high energy (0.9 MeV) electron irradiation on surge currents of high-voltage 4H-SiC JBS was investigated in the microsecond range of the forward current pulses duration. With irradiation dose  growth, the threshold of hole injection monotonically increases, and the base modulation level by minority carriers (holes) decreases. At = 1.5×1016 cm-2, the hole injection is not observed up to forward voltage values of ~ 30 V and forward current density j  9000 A/cm2.

Low frequency noise has been studied in power4H-SiC MOSFETs after proton(15 MeV) irradiation. The noise was studied at room temperature in the frequency range 1 Hz−50 kHz after irradiation with doses of 1012 ≤Ф≤ 6•1013 cm−2. Frequency dependence of the spectral noise density SI follows with good accuracy to the law SI∝1/f. The correlation between the saturation current of the output characteristics of Id(Vd) and the level of low-frequency noise is established. In the dose range Ф studied the value of the saturation current varies within about 20%, while the noise level changes by 2orders of magnitude. From the data of noise spectroscopy, the density of traps in the gate oxide, Ntv was estimated. In non-irradiated structures Ntv ≈5.4•1018cm−3•eV−1, at  = 6•1013 cm−2, Ntv increases to a value of Ntv ≈7.2•1019cm−3•eV−1.

AbstractPhotoluminescence (PL) spectra have been studied in 3 C -SiC/4 H -SiC heterostructures and 3 C ‑SiC single crystals. It was shown that epitaxial 3 C -SiC layers grown on 4 H -SiC substrates have a markedly poorer crystal perfection than do 3 C -SiC single crystals. It was found that doping with aluminum gives rise to a characteristic PL both in epitaxial layers and in 3 C -SiC single crystals. At the same time, the electron irradiation of epitaxial layers does not give rise to defect-related PL, in contrast to what is observed for single crystals. An assumption is made that the twin boundaries existing in epitaxial 3 C -SiC layers can serve as getters of radiation defects that are components of donor–acceptor pairs responsible for the “defect-related” PL.

Получена 4 июля 2018 г.Принята к печати 9 июля 2018 г

AbstractA fractal-percolation system that includes extended defects and random fluctuations in the alloy composition is formed during the growth of device structures based on Group-III nitrides. It is established that the specific features of this system are determined not only by the growth conditions. It is shown that the diversity of the electrical and optical properties of InGaN/GaN LEDs (light-emitting diodes) emitting at wavelengths of 450–460 and 519–530 nm, as well as that of the electrical properties of AlGaN/GaN HEMT (high-electron-mobility transistor) structures, is due to modification of the properties of the fractal-percolation system both during the growth process and under the action of the injection current and irradiation. The influence exerted by these specific features on the service life of light-emitting devices and on the reliability of AlGaN/GaN HEMT structures is discussed.

AbstractJBS diodes based on 4 H -SiC irradiated with electrons and protons are studied. This is carried out by using the methods of capacitance–voltage and current–voltage characteristics. It is concluded that, for both kinds of irradiation, deep centers are formed in the upper half of the band gap of silicon carbide. This leads to a sharp decrease in the concentration of ionized carriers in the conduction band and to an exponential increase in the resistance of the base regions of the structures under study.

AbstractMathematical simulation of the cascade of displacements in SiC is used to consider the specific features of Frenkel-pair generation upon the scattering of 8- and 15-MeV protons. The distribution histograms of energies acquired not only by primary knocked-out atoms, but also by recoil atoms generated in displacement cascades, are calculated. An analysis of the histograms considers two energy ranges. In the first range of “low” energies, the spontaneous recombination of genetically related Frenkel pairs is dominant. Recoil atoms in the second range have a higher energy, which enables these atoms to leave the spontaneousrecombination zone and dissociate into isolated components. The compensation of lightly doped n - and p -4 H -SiC samples grown by gas-phase epitaxy is experimentally studied under irradiation with 8- and 15-MeV protons. The carrier removal rates are measured. The calculated and experimental data are compared and estimates are obtained for the size of the spontaneous-recombination zone.

Исследовано воздействие протонного облучения с энергией 8 МэВ на эпитаксиальные слои n-3C-SiC, выращенные методом сублимации на полуизолирующих подложках 4H-SiC. Изменения параметров образцов регистрировали методом эффекта Холла и по спектрам фотолюминесценции. Метод Холла был применен для раздельной оценки влияния облучения на концентрацию и подвижность носителей заряда. Скорость удаления носителей (Vd) составила ~110 см-1. Полная компенсация образцов с исходной концентрацией носителей заряда 6.5·1017 см-3 наблюдалась при дозах облучения ~6·1015 см-2. Подвижность носителей заряда при таких дозах облучения уменьшалась всего в 2.5 раза. По сравнению с 4H и 6H карбида кремния не было отмечено значительного увеличения интенсивности так называемой "дефектной" фотолюминесценции. DOI: 10.21883/FTP.2017.08.44795.8535

Исследовано изменение вольт-амперных характеристик и величины нескомпенсированной донорной примеси (Nd-Na) в базе диодов Шоттки и JBS-диодов на основе 4H-SiC при их облучении электронами с энергией 0.9 MeV и протонами с энергией 15 MeV. Скорость удаления носителей при облучении электронами составила 0.07-0.15 cm-1, а при облучении протонами 50-70 cm-1. Показано, что исследованные приборы сохраняли выпрямляющие вольт-амперные характеристики вплоть до доз электронного облучения ~ 1017 cm-2. Показано, что радиационная стойкость исследованных приборов на основе SiC существенно превосходит радиационную стойкость кремниевых p-i-n-диодов с аналогичными напряжениями пробоя. DOI: 10.21883/PJTF.2017.22.45262.16921