一种带P型埋层的4H-SiC PiN二极管

碳化硅(SiC)PiN二极管是应用在高压大功率整流领域中的一种重要的功率二极管。受SiC外延材料的载流子寿命限制以及常规SiC PiN二极管较低的阳极注入效率的影响,SiC PiN二极管的正向导通性能较差,这极大限制了其在高压大电流领域的应用。文章提出了一种带P型埋层的4H-SiC PiN二极管,较常规SiC PiN二极管增强了阳极区的少子注入效率,降低了器件的导通电阻,增大了正向电流。仿真结果表明,当正向偏压为5 V时,引入P型埋层的SiC PiN二极管的正向电流密度比常规SiC PiN二极管提升了52.8%。     

SiC power diodes provide breakthrough performance for a wide rangeof applications

The electrical performance of silicon carbide (SiC) power diodes is evaluated and compared to that of commercially available silicon (Si) diodes in the voltage range from 600 V through 5000 V. The comparisons include the on-state characteristics, the reverse recovery characteristics, and power converter efficiency and electromagnetic interference (EMI). It is shown that a newly developed 1500-V SiC merged PiN Schottky (MPS) diode has significant performance advantages over Si diodes optimized for various voltages in the range of 600 V through 1500 V. It is also shown that a newly developed 5000 V SiC PiN diode has significant performance advantages over Si diodes optimized for various voltages in the range of 2000 V through 5000 V. In a test case power converter, replacing the best 600 V Si diodes available with the 1500 V SiC MPS diode results in an increase of power supply efficiency from 82% to 88% for switching at 186 kHz, and a reduction in EMI emissions     

碳化硅器件发展概述

概要介绍了第三代半导体材料碳化硅(SiC)在高温、高频、大功率器件应用方面的优势,结合国际上SiC肖特基势垒二极管,PiN二极管和结势垒肖特基二极管的发展历史,介绍了SiC功率二极管的最新进展,同时对我国宽禁带半导体SiC器件的研究现状及发展方向做了概述及展望。     

SiC power Schottky and PiN diodes

The present state of SiC power Schottky and PiN diodes are presented in this paper. The design, fabrication, and characterization of a 130 A Schottky diode, 4.9 kV Schottky diode, and an 8.6 kV 4H-SiC PiN diode, which are considered to be significant milestones in the development of high power SiC diodes, are described in detail. Design guidelines and practical issues for the realization of high-power SiC Schottky and PiN diodes are also presented. Experimental results on edge termination techniques applied to newly developed, extremely thick (e.g., 85 and 100 μm) 4H-SiC epitaxial layers show promising results. Switching and high-temperature measurements prove that SiC power diodes offer extremely low loss alternatives to conventional technologies and show the promise of demonstrating efficient power circuits. At sufficiently high on-state current densities, the on-state voltage drop of Schottky and PiN diodes have been shown to be comparable to those offered by conventional technologies     

Silicon carbide PiN and merged PiN Schottky power diode models implemented in the Saber circuit simulator

Dynamic electrothermal circuit simulator models are developed for silicon carbide power diodes. The models accurately describe the temperature dependence of on-state characteristics and reverse-recovery switching waveforms. The models are verified for the temperature dependence of the on-state characteristics, and the di/dt, dv/dt, and temperature dependence of the reverse-recovery characteristics. The model results are presented for 1500 V SiC Merged PiN Schottky (MPS) diodes, 600 V Schottky diodes, and 5000 V SiC PiN diodes. The devices studied have current ratings from 0.25 A to 5 A and have different lifetimes resulting in different switching energy versus on-state voltage trade-offs. The devices are characterized using a previously reported test system specifically designed to emulate a wide range of application conditions by independently controlling the applied diode voltage, forward diode current, di/dt, and dv/dt at turn-off. A behavioral model of the test system is implemented to simulate and validate the models. The models are validated for a wide range of application conditions for which the diode could be used.     

用于高功率密度功率因素校正的新一代600V砷化镓肖特基二极管

在200W连续导通模式功率因数校正（PFC）系统中，新一代600V砷化镓（GaAs）肖特基二极管与硅和碳化硅（SiC）二级管比较，砷化镓、碳化硅在PFC系统中的损耗减少高达25％。由于砷化镓有较低的结电容，砷化镓相对碳化硅高的通态损耗被较低的MOSFET损耗弥补了。和碳化硅技术相比，砷化镓有成本和可靠性优势。对于高频和高密度应用来说，新一代的砷化镓二级管是很有前景的。     

Static and dynamic characterization of large-areahigh-current-density SiC Schottky diodes

The static and dynamic characteristics of large-area, high-voltage 4H-SiC Schottky barrier diodes are presented. With a breakdown voltage greater than 1200 V and a forward current in excess of 6 A at 2 V forward bias, these devices enable for the first time the evaluation of SiC Schottky diodes in practical switching circuits. These diodes were inserted into standard test circuits and compared to commercially available silicon devices, the results of which are reported here. Substituting SiC Schottky diodes in place of comparably rated silicon PIN diodes reduced the switching losses by a factor of four, and virtually eliminated the reverse recovery transient. These results are even more dramatic at elevated temperatures. While the switching loss in silicon diodes increases dramatically with temperature, the SiC devices remain essentially unchanged. The data presented here clearly demonstrates the distinct advantages offered by SiC Schottky rectifiers, and their emerging potential to replace silicon PIN diodes in power switching applications     

Design rules for field plate edge termination in SiC Schottkydiodes

Practical design of silicon carbide (SiC) Schottky diodes incorporating a field plate necessitates an understanding of how the addition of the field plate affects the performance parameters and the relationship between the diode structure and diode performance. In this paper, design rules are presented for SiC Schottky diodes that incorporate field plate edge termination. The use of an appropriate field plate edge termination can improve the reverse breakdown voltage of a SiC Schottky diode by a factor of two. Reverse breakdown voltage values can be obtained that are up to 88% of the theoretical maximums     

Characterization of hard- and soft-switching performance of high-voltage Si and 4H-SiC PiN diodes

This paper presents a study of the performance of high-voltage Si and 4H-SiC diodes in a DC-DC buck converter. Device operation in both hard- and zero-voltage switching conditions is presented with the help of measurements and two-dimensional (2-D) mixed device-circuit simulations. Experimental results show that SiC PiN diodes have a strong potential for use in high-speed high-voltage power electronics applications operating at high temperature. A combination of low excess carrier concentration and low carrier lifetime results in superior switching performance of the 4H-SiC diode over ultrafast Si diodes. Soft switching is shown to minimize the switching loss and allow operation at higher switching frequencies using Si diodes. The power loss of 4H-SiC diodes is dominated by conduction loss. Consequently, soft-switching techniques result in a marginal reduction in power loss. However, the low overall power loss implies that SiC diodes can be used at very high switching frequencies even in hard-switching configurations.     

Dual metal SiC Schottky rectifiers with low power dissipation

Nickel and titanium are the most commonly used metals for Schottky barrier diodes on silicon carbide (SiC). Ti has a low Schottky barrier height (i.e. 0.8 eV on 6H-SiC), whilst Ni has a higher barrier (i.e. 1.25 eV). Therefore, the first metal allows to achieve a low forward voltage drop V_F but leads to a high leakage current. On the other hand, the second one presents the advantage of a lower reverse leakage current but has also a high value of V_F. In this work, dual-metal-planar (DMP) Schottky diodes on silicon carbide are reported. The rectifying barrier was formed by using an array of micrometric Ti and Ni₂Si (nickel silicide) stripes. This low/high Schottky barrier allowed to combine the advantages of the two metals, i.e. to fabricate diodes with a forward voltage drop close to that of a Ti diode and with a level of reverse current comparable to that of a Ni₂Si diode. Under the application point of view, using this kind of barrier can lead to a reduction of the device power dissipation and an increase of the maximum operating temperature.     

SiC肖特基二极管的物理模型参数提取

碳化硅(SiC)作为新型材料,在高温、高频和大功率等领域中具有很大的潜力.SiC功率半导体器件在电力电子电路中应用广泛,提取精确的物理模型参数对电力电子电路设计尤为重要.在对SiC肖特基二极管动态特性及其物理模型的分析基础上,确定了其关键的模型参数.结合Matlab和Saber仿真软件,对仿真波形和实验波形进行了对比,并以仿真波形和实验波形的相关系数及迭代次数为目标函数来改进粒子群算法,以改进粒子群优化(IPSO)算法对SiC肖特基二极管内部关键模型参数进行优化辨识.最后,针对IDW30G65C5型号的整流二极管,提取了精确的模型参数,并验证了其有效性.     

A comparison of silicon and gallium arsenide large signal IMPATT diode behaviour between 10 and 100 GHz

A large-signal computer simulation of an IMPATT diode has been used to investigate the differences between gallium arsenide and silicon IMPATT diodes. The variations of efficiency with frequency, current density, series resistance, amount of punch-through and reverse saturation currents are all investigated.With no ‘parasitic’ effects the silicon diode efficiency remains almost constant between 10 and 100 GHz, whereas the efficiency of gallium arsenide diodes is higher than that of silicon diodes at 10 GHz but decreases to the silicon diode efficiency at 100 GHz. A lower residual avalanche particle current in gallium arsenide diodes results in a higher susceptibility to reverse saturation currents. In silicon diodes the higher material resistivity affects the efficiency more than in gallium arsenide diodes, the removal of series resistance by having a punched-through diode does not necessarily increase the efficiency. The difference between experimental results quoted in the literature and the theoretical calculations are considered in terms of these effects. By considering the differences in ionization coefficients and velocities between the materials the lower efficiency of silicon diodes compared to gallium arsenide diodes is explained, also the lower breakdown voltage of gallium arsenide diodes compared to silicon diodes of the same frequency, and the ‘forward-bias’ effect found at high frequencies in gallium arsenide diodes.     

Nonlinear properties of IMPATT devices

The basic principles of IMPATT diodes as microwave devices are reviewed and the current status of these devices concerning power output and efficiency is given. The main purpose of this paper, however, is to discuss the nonlinear properties of these diodes which are useful in the design of amplifiers, oscillators, and other microwave devices. The main results of this paper are obtained from a digital computer analysis where an approximate, but realistic, diode model is employed. A detailed comparison of complementary silicon diodes as well as GaAs diodes concerning power output and efficiency is given. The effects of doping profile, current density, temperature, and material parameters on the performance of these devices have been investigated and are summarized. Saturation effects which limit the efficiency and power output of these devices are described and optimum efficiencies which can be achieved for various doping profiles are given. A comparison between single-sided and double-drift diodes in both silicon and GaAs is also presented.     

大功率肖特基SiC二极管热特性研究

基于小电流下肖特基结正向压降的温度特性,建立了温升测量系统。利用该系统对肖特基SiC二极管的瞬态温升进行了测量,结果显示瞬态温升曲线呈阶梯状变化。利用结构函数的方法对瞬态温升曲线进行处理,分析了肖特基SiC二极管在热流传输路径上的热阻构成。研究了三引脚封装的肖特基SiC二极管在相同大功率的条件下,两正极引脚单独使用和并联使用时的热阻特性,结果显示,在两正极引脚并联使用时,其热阻比单独作用时减少一半,这表明三引脚封装的肖特基SiC二极管的两个正极是并联的,并共用一个负极和散热片。     

Avalanche robustness of SiC Schottky diode

Reliability is one of the key issues for the application of Silicon carbide (SiC) diode in high power conversion systems. For instance, in high voltage direct current (HVDC) converters, the devices can be submitted to high voltage transients which yield to avalanche. This paper presents the experimental evaluation of SiC diodes submitted to avalanche, and shows that the energy dissipation in the device can increase quickly and will not be uniformly distributed across the surface of the device. It has been observed that failure occurs at a fairly low energy level (< 0.3 J/cm²), on the edge of the die, where the electrical field intensity is the greatest. The failure results in the collapse of the voltage across the diode (short-circuit failure mode). If a large current is maintained through the diode after its failure, then the damage site is enlarged, masking the initial failure spot, and eventually resulting in a destruction of the device and an open circuit.     

An Efficient Power-Factor Correction Scheme for Plasma Display Panels

This paper presents an efficient power-factor correction (PFC) scheme for plasma display panels (PDPs) to reduce harmonic currents and power consumption. A high-efficiency interleaved boost converter is proposed, which can reduce the conduction losses and diode reverse-recovery problems in the continuous-conduction-mode operation. A zero-current switching (ZCS) condition is obtained to solve the reverse-recovery problems of the output diodes. In addition, a control strategy is suggested for the use of the proposed converter in a practical design. A high power factor can be achieved without sensing the input voltage. The analysis of the proposed converter and its design considerations are presented in detail. The experimental results based on a 600-W prototype are discussed to evaluate the proposed converter for a PFC circuit in a 50-in PDP power supply unit.     

一种新型SiC SBD的高温反向恢复特性

与传统硅基功率二极管相比,碳化硅肖特基势垒二极管(SiC SBD)可提高开关频率并大幅减小开关损耗,同时有更高的耐压范围.设计并制作了具有场限环结终端和Ti肖特基接触的1.2 kV/30 A SiC SBD器件,研究了该SiC SBD在100~300℃时的反向恢复特性.实验结果表明,温度每上升100℃,SiC SBD反向电压峰值增幅为5%左右,而反向恢复电流与反向恢复时间受温度影响不大;温度每升高50℃,反向恢复损耗功率峰值降低5%.实验结果表明该SiCSBD在高温下能够稳定工作,且具有良好的反向恢复特性,适用于卫星、航空和航天探测、石油以及地热钻井探测等需要大功率、耐高温和高速器件的领域.     

High-power K-band silicon avalanche-diode oscillators

Large-size silicon avalanche diodes operating at a current density of over 8000 A/cm²have produced pulsed power output of 17 W at 24.0 GHz, and 28 W at 10.5 GHz. A decrease in average voltage up to 25 percent has been observed across the diode during oscillation at its peak power output. This and other experimental results are discussed in terms of a "quenched-plasma" effect in the diode.     

High-power generation in IMPATT devices in the 100-200-GHz range

A silicon double-drift IMPATT diode with high uniform doping levels was simulated. Simulation results show that it is possible for silicon IMPATT diodes to generate extremely high pulsed output power for frequencies above 100 GHz under high current-density operation. The highest output power matched to a 1-Ω load resistance obtained at 150 GHz is 37.7 W with a DC current density of 200 kA/cm², although the calculated power conversion efficiency is low. It is also shown that the low-power conversion efficiency limits the diode's continuous wave power operation     

Comparison of current-voltage characteristics of n- and p-type 6H-SiC Schottky diodes

Current-voltage (I–V) characteristics of n- and p-type 6H−SiC Schottky diodes are compared in a temperature range of room temperature to 400°C. While the room temperature I–V characteristics of the n-type Schottky diode after turn-on is more or less linear up to ∼100 A/cm², the I–V characteristics of the p-type Schottky diode shows a non-linear behavior even after turn-on, indicating a variation in the on-state resistance with increase in forward current. For the first time it is shown that at high current densities (>125 A/cm²) the forward voltage drop across p-type Schottky diodes is lower than that across n-type Schottky diodes on 6H−SiC. High temperature measurements indicate that while the on-state resistance of n-type Schottky diodes increases with increase in temperature, the on-state resistance of p-type Schottky diodes decreases with increase in temperature up to ∼330 K.