High-voltage 4H-SiC Research Articles

Comparative Performance Evaluation of High-Voltage Bidirectional, Conventional and Superjunction Planar DMOSFETs in 4H-SiC

We quantitively compare the static and dynamic performance for high-voltage SiC bidirectional (BD) conventional and superjunction (SJ) DMOSFETs by using 3D TCAD simulations. We extract the specific on-resistance (RON,sp) and the total specific switching charge (QT,sp), which is a sum of the specific gate charge (QG,sp) and drain charge (QDS,sp) to quantify both the static and switching characteristics respectively. We also develop a new Figure-of-Merit (FoM), which is the product of RON,sp . QT,sp, to evaluate the overall performance. We show that the high-voltage 4H-SiC BD SJ DMOSFET has the best FoM with substantial (>58%) improvement, compared to the BD conventional DMOSFETs, which increases with increasing breakdown voltage.

A Novel Tapered Doping Tail Modulated Single Junction Termination Extension for High Voltage 4H-SiC Devices

A Novel Tapered Doping Tail Modulated Single Junction Termination Extension for High Voltage 4H-SiC Devices

Development of 400 V-Tolerant Single-Event Effect Hardened 4H-SiC Schottky Diode With Linear Energy Transfer Upto 83.5 MeV⋅cm2/mg

A novel 4H-SiC junction barrier Schottky (JBS) with deep linear graded doping (DLGD) P junction structure is proposed and fabricated to enhance the radiation tolerance of Single-Event Effect (SEE). The radiation-hardened function of the proposed new structure is confirmed via two-dimensional numerical simulation and SEE experiment. The hardened device was tested under heavy ion irradiation with linear energy transfer (LET) up to 83.5 MeV·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /mg. Test results show that the single-event leakage current (SELC) threshold voltage of the hardened device is 400 V, which is the best SEE radiation-hardened performance reported so far for high-voltage 4H-SiC JBS. Compared with the state-of-the-art counterparts, this work is about 2 times improvement in SELC threshold voltage.

Effect of Proton Irradiation on the Properties of High-Voltage Integrated 4H-SiC Schottky Diodes at Operating Temperatures

Effect of Proton Irradiation on the Properties of High-Voltage Integrated 4H-SiC Schottky Diodes at Operating Temperatures

Влияние протонного облучения на свойства высоковольтных интегрированных 4H-SiC диодов Шоттки в рабочем диапазоне температур

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.

Effect of proton irradiation on the properties of high-voltage integrated 4H-SiC Schottky diodes at operating temperatures

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 175oC). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with U_b = 600 V, the fluence range was 5·1013-1·1014 cm-2; for devices with U_b=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. Keywords: Silicon carbide, Schottky diodes, proton irradiation, current-voltage characteristics, annealing.

Features of the Carrier Concentration Determination during Irradiation of Wide-Gap Semiconductors: The Case Study of Silicon Carbide

In this paper, the features of radiation compensation of wide-gap semiconductors are discussed, considering the case study of silicon carbide. Two classical methods of concentration determination are compared and analyzed: capacitance-voltage (C-V) and current-voltage (I-V) characteristics. The dependence of the base resistance in high-voltage 4H-SiC Schottky diodes on the dose of irradiation by electrons and protons is experimentally traced in the range of eight orders of magnitude. It is demonstrated that the dependence of the carrier concentration on the irradiation dose can be determined unambiguously and reliably in a very wide range of compensation levels, based on the results of measuring the I-V characteristics. It is shown that the determination of the carrier removal rate using the I-V characteristics is more correct than using the C-V characteristics, especially in the case of high radiation doses.

Exploration on Electrical Isolation Between High-Voltage SiC Thyristor and Small-Signal Devices for Smart Power Devices

The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Smart Discrete</i> concept which monolithically integrates a vertical high-voltage power device with low-voltage smart circuits has been widely adopted in silicon world for many years and may bring similar benefits to SiC world. For example, it is highly desirable to integrate a gate driver circuit onto a high-voltage SiC thyristor for ultra-fast turn-on. However, the electrical isolation between the vertical high-voltage power device and the low-voltage circuit elements remains a major technical challenge for silicon, and even more so for SiC due to the very limited processing options. In this article, we propose a combination of shallow junction isolation (JI) and partial dielectric isolation (DI) for high-voltage 4H-SiC smart thyristor, which is monolithically integrated with low-voltage nMESFET circuits. The characterization of fabricated devices and analysis of leakage currents across the isolation structure have been done to experimentally verify the feasibility of the isolation method. 8 V parasitic lateral NPNP thyristor between a 6.3 kV 4H-SiC thyristor and isolation moats, 175 V lateral PNP transistor between the passive resistor and isolation moats, and 10 V lateral reverse-biased p-n diode between nMESFET and isolation moats are experimentally demonstrated.

Annealing High-Voltage 4H-SiC Schottky Diodes Irradiated with Electrons at a High Temperature

Annealing High-Voltage 4H-SiC Schottky Diodes Irradiated with Electrons at a High Temperature

Electron irradiation hardness of high-voltage 4H-SiC Schottky diodes in the operating temperature range

Effect of irradiation with 0.9 MeV electrons on the parameters of 4H-SiC Schottky diodes with a limiting blocking voltage Ub=600 and 1700 V was studied for the first time in the range of operating temperatures Ti (23 and 175oC). The range of fluences Phi was 1·1016-2·1016 cm-2 for devices with Ub=600 V and 5·1015-1.5·1016 cm-2 for devices with Ub=1700 V. Irradiation at room temperature increases significantly the differential resistance of the base of the diodes. Irradiation with the same doses at Ti=175oC --- i.e. at limiting operating temperature of devices, does not affect practically the parameters of current-voltage characteristics. Nevertheless, the DLTS spectra demonstrate a significant increase in the concentration of deep levels in the upper half of the band gap not only after irradiation at room temperature, but also after irradiation at Ti=175oC. Keywords: silicon carbide, Schottky diodes, electron irradiation, current-voltage characteristics, DLTS spectra.

A multiple-floating-zone-assisted graded-step-JTE for high-voltage 4H-SiC GTO thyristor

A multiple-floating-zone-assisted graded-step-JTE for high-voltage 4H-SiC GTO thyristor

Effect of high temperature irradiation with 15 MeV protons on characteristics of power SiC Schottky diodes

The effect of high-temperature irradiation with 15 MeV protons on the parameters of high-voltage 4H-SiC Schottky diodes has been studied at irradiation temperatures of 23–500 °C and doses in the range from 7 × 1013 to 2 × 1014 cm−2. After the irradiation with a dose of 1014 cm−2 at room temperature, the forward current at a forward voltage U = 2 V decreases by ~10 orders of magnitude. In this case, the cutoff voltage Uc, equal to ~0.6 V in unirradiated devices, decreases to Uc ≈ 0.35 V. By contrast, irradiation with the same dose at a temperature of 500 °C leads to an increase in Uc up to Uc ≈ 0.8 V. At the same reference value of the forward voltage U = 2 V, the decrease in current, compared to the value in unirradiated devices, was smaller by ~4 orders of magnitude. In the entire range of doses and irradiation temperatures under study, the forward current–voltage characteristic of diodes at U > Uc is linear up to U ≤ 2 V.

High-Voltage Avalanche 4H-SiC Diodes with a Protective Semi-Insulating Area

High-Voltage Avalanche 4H-SiC Diodes with a Protective Semi-Insulating Area

High-Voltage 4H-SiC Schottky Diodes with Field-Plate Edge Termination

High-voltage (2000V) 4H-SiC Schottky diodes are fabricated. To suppress the premature breakdown at the edge of diode structures, a field plate is formed as the edge termination. In this plate, an insulator layer is formed via the self-aligned implantation of high-energy (53 MeV) argon ions into 4H-SiC. To mask the active region of the diodes, 10–12-μm-thick nickel columns with vertical walls are grown on Schottky contacts by local electrochemical deposition. A comparison of the current–voltage characteristics of terminated and nonterminated diodes shows that the forward current–voltage characteristics barely degrade after implantation, whereas the reverse current–voltage characteristics are greatly improved. Both the forward and reverse current–voltage characteristics of terminated diodes are well described in terms of the classical thermionic emission model if lowering of the Schottky-barrier height with increasing bending of energy bands is taken into account.

TCAD Simulation of High-Voltage 4H-SiC Diodes with an Edge Semi-Insulating Region

TCAD Simulation of High-Voltage 4H-SiC Diodes with an Edge Semi-Insulating Region

A Compact Trench-Assisted Space-Modulated JTE Design for High-Voltage 4H-SiC Devices

This article proposes a compact trench-assisted space-modulated junction termination extension (TSM-JTE) design for high-voltage 4H-silicon carbide (SiC) devices. In this design, trench structures are introduced into the JTE region to effectively split the termination region into three functional zones. The proposed termination structure is cost effective in terms of the chip area it occupies; for devices rated at 10 kV, the termination structure extends the edge of the device by only 250 μm. Requiring only one implant, it is relatively cheap to fabricate, while a wide implantation dose window endures that is relatively insensitive to variations in dose that may occur during processing. The same advantages occur at 20 kV, the TSM-JTE proving to have the best tradeoff between maximum breakdown voltage and implantation window, compared with other single implant termination designs, achieving this in 500 μm of termination length. At 3.3 kV, a 110-μm TSM-JTE retains its advantages over the other JTE designs, but floating field rings are expected to consume less area, though this is not the case at the higher voltages.

Radiation Resistance of High-Voltage Silicon and 4H-SiC Power p-i-n Diodes

The different effect of displacement damage produced by neutron irradiation on the static characteristics of 4.5-kV silicon and 4H silicon carbide (SiC) p-i-n power diodes is explained using deep level transient spectroscopy (DLTS), ${C}$ – ${V}$ profiling, and open-circuit voltage decay (OCVD) measurements. The number of introduced defects in SiC is higher, also the degradation of carrier lifetime and carrier removal proceeds more swiftly in SiC than those in silicon. However, smaller dimensions and a higher doping level of the n-base of the SiC diode compensate for these negative effects. As a result, the SiC p-i-n diode exhibits substantially higher resistance to neutron irradiation at higher fluences when the diode loses its ON-state carrier modulation capability. SiC also shows a negligible effect of irradiation on leakage current due to the wider bandgap. One may assume a better reliability of SiC bipolar devices over the silicon in a high neutron radiation environment.

DV/dt testing of high voltage 4H-SiC Schottky diodes with different types of metal-polymeric packages

The dV/dt values for 4H-SiC Schottky type diodes with different type packages have been determined experimentally. It is determined that experimental dV/dt values for 4H-SiC Schottky type diodes in metal-polymeric packages (SOT-89, QFN, PQFN, TO-220) are varying in interval of 645¸1103 V/ns. It is established that the dV/dt dependence on maximal amplitude of reverse voltage demonstrate nonlinear character (close to parabolic dependence) for all studied SiC Schottky type diodes in different type packages.

Determination of dV/dt and dI/dt characteristics for high voltage 4H-SiC Schottky diodes with different types of metal-polymeric packages

The dV/dt and dI/dt characteristics for 4H-SiC Schottky type diodes with different type metal-polymeric packages have been studied experimentally. It is determined that experimental dV/dt values for 4H-SiC Schottky type diodes in large-sized and small-sized metal-polymeric packages type (TO-220, SOT-89, QFN, PQFN) are varying in interval of 753÷1087 V/ns. For the first for time 4H-SiC Schottky type diodes have been determined experimentally another important diode’s characteristics dI/dt which are varying in interval of 1.91÷4.00 A/ns for all diodes It is established that package’s size miniaturization not lead to characteristics degradation (dV/dt and dI/dt) during of impulse mode of operation that is positive factor for the for diode failure-free operation during of impulse mode.

Impact of 0.9 MeV electron irradiation on main properties of high voltage vertical power 4H-SiC MOSFETs

We report the results of a study into the impact of irradiation with 0.9 MeV electrons on the main properties of 4H-SiC MOSFETs of 1.2 kV class at irradiation doses Φ within the range from 0.125 to 3 MGy (fluence F from 75 × 1014 to 1.2 × 1016 cm−2). The effects of irradiation on the threshold voltage, leakage current, output characteristics, and channel electron mobility have been studied. The results obtained are compared with the known data on the irradiation of high-voltage 4H-SiC MOSFETs with 4.5 MeV electrons and γ-photons from a60Co source. It is shown that the parameter variations of the MOSFETs under influence of irradiation depends on both the dose and the electron energy. A high radiation hardness of the structures under study has been demonstrated.