SiC Schottky Diodes Research Articles

Effects of 10 keV Electron Irradiation on the Performance Degradation of SiC Schottky Diode Radiation Detectors

The silicon carbide (SiC) Schottky diode (SBD) detector in a SiC hybrid photomultiplier tube (HPMT) generates signals by receiving photocathode electrons with an energy of 10 keV. So, the performance of the SiC SBD under electron irradiation with an energy of 10 keV has an important significance for the application of the SiC-HPMT. However, studies on 10 keV radiation effects on the SiC SBDs were rarely reported. In this paper, the performance degradation of the SiC SBDs irradiated by 10 keV electrons at different fluences was investigated. After the irradiation, the forward current of the SiC SBDs increased, and the turn-on voltage decreased with the irradiation fluences until 1.6 × 1016 cm−2. According to the capacitance–voltage (C-V) curves, the effective doping concentration increased slightly after the irradiation, and an obvious discrepancy of C-V curves occurred below 5 V. Moreover, as a radiation detector, the peak position of the α-particles’ amplitude spectrum changed slightly, and the energy resolution was also slightly reduced after the irradiation due to the high collection charge efficiency (CCE) still being larger than 99.5%. In addition, the time response of the SiC SBD to the 50 ns pulsed X-ray was almost not affected by the irradiation. The results indicated that the performance degradation of the SiC SBD irradiated at the fluence of 1.5 × 1017 cm−2 would not result in a deterioration of the properties of the SiC-HPMT and showed an important significance for the supplement of the radiation resistance of the SiC SBD radiation detector.

How we made the 1,000 V silicon carbide Schottky diode

How we made the 1,000 V silicon carbide Schottky diode

Local Diagnostics of Spin Defects in Irradiated SiC Schottky Diodes

Local Diagnostics of Spin Defects in Irradiated SiC Schottky Diodes

Dependence of the Silicon Carbide Radiation Resistance on the Irradiation Temperature

The effect of high-temperature electron and proton irradiation on SiC-based device characteristics is being investigated. Industrial integrated 4H-SiC Schottky diodes, each with an n-type base and a blocking voltage of either 600 V, 1200 V, or 1700 V, manufactured by Wolfspeed, are being studied. 0.9 MeV electron and 15 MeV proton irradiation were applied. It has been found that the irradiation resistance of silicon carbide Schottky diodes at high temperatures significantly exceeds their resistance at room temperature. This effect is attributed to the annealing of compensating defects induced by high-temperature irradiation. The parameters of radiation-induced defects are determined using the method of deep level transient spectroscopy (DLTS). Under high-temperature ("hot") irradiation, the spectrum of radiation-induced defects introduced into SiC appears to differ significantly from the spectrum of defects introduced at room temperature. It is suggested that approximately half of the compensation is due to radiation-induced defects formed in the bottom part of the bandgap.

Unveiling microstructural damage for leakage current degradation in SiC Schottky diode after heavy ions irradiation under 200 V

Single-event burnout and single-event leakage current (SELC) in silicon carbide (SiC) power devices induced by heavy ions severely limit their space application, and the underlying mechanism is still unclear. One fundamental problem is lack of high-resolution characterization of radiation damage in the irradiated SiC power devices, which is a crucial indicator of the related mechanism. In this Letter, high-resolution transmission electron microscopy (TEM) was used to characterize the radiation damage in the 1437.6 MeV 181Ta-irradiated SiC junction barrier Schottky diode under 200 V. The amorphous radiation damage with about 52 nm in diameter and 121 nm in length at the Schottky metal (Ti)–semiconductor (SiC) interface was observed. More importantly, in the damage site the atomic mixing of Ti, Si, and C was identified by electron energy loss spectroscopy and high-angle annular dark-field scanning TEM. It indicates that the melting of the Ti–SiC interface induced by localized Joule's heating is responsible for the amorphization and the possible formation of titanium silicide, titanium carbide, or ternary phases. The mushroom-like hillock in the Ti layer can be attributed to Rayleigh–Taylor instability, as another evidence for ever-happened localized melting near the Schottky interface. These modifications at nanoscale in turn cause localized degradation of the Schottky contact, resulting in permanent increase in leakage current. This experimental study provides very valuable clues for a thorough understanding of the SELC mechanism in SiC diodes.

Reliability Improvement of Grid Connected PV Inverter Considering Monofacial and Bifacial Panels Using Hybrid IGBT

The development of bifacial photovoltaics has led to significant advancements in solar energy. Unlike traditional solar panels, which only generate electricity from the front side, these panels capture the energy from the rear and front surfaces. Bifacial photovoltaics utilize a dual-sided absorption to capture the sunlight that falls on nearby structures and the ground. This technology helps boost their efficiency and makes them an economical and sustainable choice. Furthermore, the increased energy production from the rear side of bifacial panels may lead to higher voltage fluctuations, which affects the thermal stability of PV inverter. Nevertheless, PV inverter is regarded as critical component which affects the reliability performance. Hence in this paper reliability improvement methodology with hybrid IGBT is proposed for the PV inverter. The hybrid IGBT consists of Silicon (Si) IGBT and Silicon Carbide (SiC) Schottky diode. A test case of 3-kW Monofacial and Bifacial grid connected PV inverter system with various albedos is considered. Mission profile for one year at Hyderabad, India location is logged for the assessment. B10 lifetime is calculated for the proposed hybrid IGBT. The effectiveness of the proposed hybrid IGBT is evaluated in comparison with conventional IGBT. The proposed hybrid IGBT significantly improves the reliability performance of the PV inverter.

Comparison between conventional Si and new generation of SiC detector for high proton energy spectrometry

A SiC Schottky diode and a Si surface barrier detector have been compared during Rutherford backscattering spectrometry (RBS) using 2–3 MeV proton beams. Both detectors are suited to detect high energetic ions with high-energy resolution for spectroscopic analysis. The correlations between the detector parameters and the surface passivating layers, ion energy and current dependence, ion penetration depth, detection efficiency and energy resolution, are outlined. Comparative RBS analysis performed using SiC and Si detectors has been investigated to highlight the advantages and disadvantages of the use of SiC with respect to the traditional Si junction detector. RBS spectrometry has been carried out using projectiles of proton incident on different targets to analyse their composition and thickness by the detection of the backscattered ions revealed by Si and SiC detectors.

Fast and Accurate Data Sheet Based Analytical Switching Loss Model for a SiC MOSFET and Schottky Diode Half-Bridge

Fast and Accurate Data Sheet Based Analytical Switching Loss Model for a SiC MOSFET and Schottky Diode Half-Bridge

An improved hybrid photon detector based on a SiC Schottky diode

In order to improve the temporal response of SiC-HPMTs, a new SiC detector with a faster time response (leading edge 1.5 ns, FWHM 4 ns) was developed for constructing an improved SiC-HPMT. Then the properties of the improved SiC-HPMT were studied in detail. Compared with those of the previous SiC-HPMT, the temporal response of the improved SiC-HPMT, with a leading edge of about 2 ns and a FWHM of less than 5ns was effectively improved. The maximum linear current that exceeded 630 mA depends on both the accelerating and focusing voltage (Va) and the bias voltage (VSiC) of the SiC detector, but has a strong dependence on Va. The scintillation detector comprised of the improved SiC-HPMT and an EJ228 scintillator can accurately obtain the multiple peaks characteristic of the pulsed X-ray source, which indicates that the improved SiC-HPMT can well satisfy the requirements for measuring the time information of fast pulsed radiation fields. In addition, the SiC-HPMT should be placed at the position that deviates from the radiation beam to avoid the direct irradiation on the SiC detector. The improved SiC-HPMT will further expand its application in pulsed radiation field measurements and become a supplement for existing photoelectric detectors.

The effect of wafer thinning and thermal capacitance on chip temperature of SiC Schottky diodes during surge currents

Due to superior material properties of SiC for high-voltage devices, SiC Schottky diodes are used in energy-conversion systems such as solar-cell inverters, battery chargers, and power modules for electric cars and unmanned aerial vehicles. The reliable operation of these systems requires the chip temperature of SiC Schottky diodes to be maintained within the limit set by the device package. This is especially crucial during surge-current events that dissipate heat within the device. As a thermal-management method, manufactures of commercial SiC Schottky diodes have introduced wafer thinning practices to reduce the thickness of the SiC chip and, consequently, to reduce its thermal resistance. However, this also leads to a reduction in the thermal capacitance. In this paper, we present experimental data and theoretical analysis to demonstrate that the reduced thermal capacitance has a much larger adverse effect in comparison to the beneficial reduction of the thermal resistance. An implication of the presented results is that, contrary to the adopted wafer thinning practices, SiC Schottky diodes fabricated without wafer thinning have superior surge-current capability.

Evaluation of antiparallel SiC Schottky diode in SiC MOSFET phase-leg configuration of synchronous rectifier

The MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiC MOSFET exhibits a high voltage drop. Therefore, SiC Schottky diodes (SBD) and SiC MOSFETs are usually used in reverse parallel to reduce power loss. However, the increase of equivalent junction capacitance due to the addition of an external SiC SBD could bring larger turn-on current on opposite power transistor of the phase-leg. Furthermore, as the parasitic inductance associated with layout hinders the prompt transfer of current between SiC SBD and body diode, the external SiC SBD cannot be fully utilized, and it may deteriorate the overall performance, especially at heavy load. We comprehensively compare power losses when SiC SBD are antiparallel or not, at different working conditions, including different layout compactness, load current and dead time. It’s hard to get the effect of loss reduction loss when add antiparallel SiC SBD due to the parasitic inductance induced by the layout. The results can provide a guidance to properly select SiC SBD in a phase-leg configuration under SR mode for freewheeling during the dead time.

Investigation of temperature and flux effects on heavy ion induced degradation in SiC Schottky diode

In this work, the effects of environmental temperature and ion flux on heavy-ion irradiation damage in commercial SiC Schottky diodes were experimentally characterized. The result shows that the room temperature (25 °C) irradiation is the worst setting than high temperatures. In particular, the reverse leakage current IR increment at the highest temperature (150 °C) is about one-fifth of that at room temperature. The damage is more serious under high flux irradiation, and the IR increment introduced by higher flux (∼10,000 ions/(cm2∙s)) is four times larger than that by lower flux (∼300 ions/(cm2∙s)). After room temperature annealing for more than one year, the DUTs still show the same damage characteristics, which indicates the degradation damage induced by heavy ions is permanent. The variation of power dissipation induced by the synergistic effect of heavy ion incident and the electric field is the root mechanism. The results would help estimate the feasibility of the usage of SiC power devices in space.

Investigation of Electrically Active Defects in SiC Power Diodes Caused by Heavy Ion Irradiation

Deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) are used to investigate electrically active defects in commercial SiC Schottky power diodes after heavy-ion microbeam irradiation at different voltages. The DLTS and MCTS spectra of pristine samples are analysed and compared to devices showing or not signatures of Single Event Leakage Current (SELC) degradation. An additional peak labelled ‘C’ with an activation energy of 0.17 eV below the conduction band edge is observed in the DLTS spectra of a sample degraded with SELC.

A Review of Power Electronic Devices for Heavy Goods Vehicles Electrification: Performance and Reliability

This review explores the performance and reliability of power semiconductor devices required to enable the electrification of heavy goods vehicles (HGVs). HGV electrification can be implemented using (i) batteries charged with ultra-rapid DC charging (350 kW and above); (ii) road electrification with overhead catenaries supplying power through a pantograph to the HGV powertrain; (iii) hydrogen supplying power to the powertrain through a fuel cell; (iv) any combination of the first three technologies. At the heart of the HGV powertrain is the power converter implemented through power semiconductor devices. Given that the HGV powertrain is rated typically between 500 kW and 1 MW, power devices with voltage ratings between 650 V and 1200 V are required for the off-board/on-board charger’s rectifier and DC-DC converter as well as the powertrain DC-AC traction inverter. The power devices available for HGV electrification at 650 V and 1.2 kV levels are SiC planar MOSFETs, SiC Trench MOSFETs, silicon super-junction MOSFETs, SiC Cascode JFETs, GaN HEMTs, GaN Cascode HEMTs and silicon IGBTs. The MOSFETs can be implemented with anti-parallel SiC Schottky diodes or can rely on their body diodes for third quadrant operation. This review examines the various power semiconductor technologies in terms of losses, electrothermal ruggedness under short circuits, avalanche ruggedness, body diode and conduction performance.

Ultrafast, room temperature rejuvenation of SiC Schottky diodes from forward current-induced degradation

In this work, we demonstrate the rejuvenation of Ti/4H-SiC Schottky barrier diodes after forward current-induced degradation, at room temperature and in a few seconds, by exploiting the physics of high-energy electron interactions with defects. The diodes were intentionally degraded to a 42% decrease in forward current and a 9% increase in leakage current through accelerated electrical stressing. The key feature of our proposed rejuvenation process is very high current density electrical pulsing with low frequency and duty cycle to suppress any temperature rise. The primary stimulus is, therefore, the electron wind force, which is derived from the loss of the momentum of the high energy electrons upon collision with the defects. Such defect-specific or “just in location” mobilization of atoms allows a significant decrease in defect concentration, which is not possible with conventional thermal annealing that requires higher temperatures and longer times. We show evidence of rejuvenation with additional improvement in leakage current (16%) and forward current (38%) beyond the pristine condition. Transmission electron microscopy, geometric phase analysis, Raman spectroscopy, and energy dispersive x-ray-spectroscopy reveal the enhancement of defects and interfaces. The ultrafast and room temperature process has the potential for rejuvenating electronic devices operating in high power and harsh environmental conditions.

Optimization for Ion Detection and Recognition From Laser-Generated Plasma Using SiC Detectors Connected in Time-of-Flight Acquisition

A silicon carbide (SiC) Schottky diode detector is employed to monitor the ion streams emitted from laser-generated plasmas and to obtain information on their kinetic energy using time-of-flight (TOF) measurements. The laser operates with nanosecond (ns) pulses, in the IR region at 1064-nm wavelength, uses single pulses with 200-mJ energy, and an intensity of about 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{10}$</tex-math> </inline-formula> W/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . Plasmas are produced in a high vacuum by irradiation different targets as polymers, ceramics, and metals. The non equilibrium plasma, back emitted orthogonally to the target surface, accelerates ions at about 110 eV per charge state and has a temperature within 70 and 100 eV growing with the atomic number of the laser irradiated target. In this article, an optimization of ion detection is checked for SiC detectors through the TOF spectra, permitting the ion recognition and angular emission. A comparison with classical ion collectors (ICs) is also presented and discussed.

Integration of SiC Devices and High-Frequency Transformer for High-Power Renewable Energy Applications

This paper presents a novel structure of Integrated SiC MOSFETs with a high-frequency transformer (I-SiC-HFT) for various high-power isolated DC–DC converters. Several resonant converters are considered for integration in this paper, including the phase-shift full-bridge (PSFB) converter, inductor–inductor–capacitor (LLC) resonant converter, bidirectional PSFB converter, and capacitor–inductor–inductor–capacitor (CLLC) resonant converter. The applications of I-SiC-HFT are focused on V2G EV battery charging systems, energy storage in DC and AC microgrids, and renewable energy systems. SiC devices, including MOSFETs, Schottky diodes, and MOSFET modules, are used in this novel structure of I-SiC-HFT. The high-frequency magnetic structure uses distributed ferrite cores to form a large central space to accommodate SiC devices. The optimized architecture of I-SiC-HFT and heatsink structure is proposed for thermal management of SiC devices. To prove the concept, a small-scale 1.5 kW prototype I-SiC-HFT is used to demonstrate the basic structure and various performance indicators through the FEM based electromagnetic simulation and DC–DC converter experiments.

A Novel Analytical Formulation of SiC-MOSFET Losses to Size High-Efficiency Three-Phase Inverters

This paper presents a novel analytical loss formulation to predict the efficiency of three-phase inverters using silicon carbide (SiC) metal—oxide—semiconductor field-effect transistors (MOSFETs). The proposed analytical formulation accounts for the influence of the output current harmonic distortion on the conduction losses as well as the impact of the output parasitic capacitances and the deadtime on the switching losses. The losses are formulated in balanced conditions to select suitable SiC MOFETs for the desired target efficiency. To validate the proposed methodology, a 3-phase inverter is designed to present full load efficiency in excess of 99% when built using SiC MOSFETs antiparalleled with SiC Schottky diodes selected for the specified full load efficiency. Experimental assessment of the designed inverter efficiency is compared with the expected values from the proposed analytical formulation and shown to match or exceed the predicted results for loads ranging from 40% to 100% of full load.

Effect of the contact area on the electrical characteristics of the Ti/6H–SiC (n) Schottky diode

In this paper, we investigated three different sizes (1.6 × 1.6, 1.6 × 0.4 and 0.4 × 0.4 mm2) of Ti Schottky diodes on n-type 6H–SiC epitaxial layers using current-voltage-temperature I–V-T measurements. At room temperature, Schottky contacts I–V characteristics are influenced by the dimensions of the contact area, the bigger and medium diodes present near-ideal behavior following the thermionic emission current theory. However, the characteristics of the smaller diode are affected by the presence of two barrier heights, which can be identified as abnormal interface inhomogeneities. The basic Schottky diode parameters are extracted by the standard Least Mean Square LMS method, recalculated and explained by the thermionic emission current theory (TE) using the Newton-Raphson method.An exhaustive analysis was carried according to the temperature in a wide range 77–500 K which also shows a deviation from the ideality at lower temperatures, thus suggesting that an inhomogeneous barrier has indeed formed and this for all three contacts.The I–V-T analysis allowed us to evaluate the Richardson constant A* in the Ti/6H–SiC Schottky diode by applying the barrier height inhomogeneities correction with the Gaussian distribution. It was close to the theoretical value.

Silicon carbide Schottky diode detector for fusion neutron yields monitoring using associated particle method

The associated particle method is proven to be one of ideal options for D-T fusion neutron detection, acquiring accurate neutron yields by monitoring α particle. Semiconductor detectors can be used to detect α particle for compact size, high energy-resolution, and stable response. SiC detector with high radiation resistance is benefit for long service time in fusion neutron monitoring. In this paper, a SiC Schottky diode detector is used to detect associated α particles for D-T fusion neutron monitoring, and successfully gets accurate neutron yields, being highly consistent with the conventional Si surface barrier detector. It is encouraging to find out SiC detector can afford 2.56 × 109 cm−2 α particles irradiation, with slight performance degradation of dark current and energy resolution, indicating that SiC detector is a promising candidate for fusion neutron detection.