High frequency doubling efficiency THz GaAs Schottky barrier diode based on inverted trapezoidal epitaxial cross-section structure

A high-performance terahertz Schottky barrier diode(SBD)with an inverted trapezoidal epitaxial cross-sectional structure featuring high varactor characteristics and reverse breakdown characteristics is reported in this paper.Inductively coupled plasma dry etching and dissolution wet etching are used to define the profile of the epitaxial layer,by which the voltage-dependent variation trend of the thickness of the metal-semiconductor contact depletion layer is modified.The simulation of the inverted trapezoidal epitaxial cross-section SBD is also conducted to explain the physical mechanism of the electric field and space charge region area.Compared with the normal structure,the grading coefficient M increases from 0.47 to 0.52,and the capacitance modulation ratio(C^(max)/C_(min))increases from 6.70 to 7.61.The inverted trapezoidal epitaxial cross-section structure is a promising approach to improve the variable-capacity ratio by eliminating the accumulation of charge at the Schottky electrode edge.A 190 GHz frequency doubler based on the inverted trapezoidal epitaxial cross-section SBD also shows a doubling efficiency of 35%compared to that 30%of a normal SBD.

Temperature-dependent characteristics of 4H-SiC junction barrier Schottky diodes

The current-voltage characteristics of 4H-SiC junction barrier Schottky （JBS） diodes terminated by an offset field plate have been measured in the temperature range of 25-300℃. An experimental barrier height value of about 0.5 eV is obtained for the Ti/4H-SiC JBS diodes at room temperature. A decrease in the experimental barrier height and an increase in the ideality factor with decreasing temperature are shown. Reverse recovery testing also shows the temperature dependence of the peak recovery current density and the reverse recovery time. Finally, a discussion of reducing the reverse recovery time is presented.

Study and optimal simulation of 4H-SiC floating junction Schottky barrier diodes' structures and electric properties

This paper stuides the structures of 4H SiC floating junction Schottky barrier diodes. Some structure parameters of devices are optimized with commercial simulator based on forward and reverse electrical characteristics. Compared with conventional power Schottky barrier diodes, the devices are featured by highly doped drift region and embedded floating junction layers, which can ensure high breakdown voltage while keeping lower specific on-state resistance, and solve the contradiction between forward voltage drop and breakdown voltage. The simulation results show that with optimized structure parameter, the breakdown voltage can reach 4.36 kV and the specific on-resistance is 5.8 mΩ.cm2 when the Baliga figure of merit value of 13.1 GW/cm2 is achieved.

Analysis and simulation of a 4H-SiC semi-superjunction Schottky barrier diode for softer reverse-recovery

In this paper, a 4H-SiC semi-superjunction （S J） Schottky barrier diode is analysed and simulated. The semi-SJ structure has an optimized design and a specific on-resistance lower than that of conventional SJ structures, which can be achieved without increasing the process difficulty. The simulation results show that the specific on-resistance and the softness factor depend on the aspect and thickness ratios, and that by using the semi-SJ structure, specific on-resistance can be reduced without decreasing the softness factor. It is observed that a trade-off exists between the specific on-resistance and the softness of the diode.

4H-SiC trench MOSFET with an integrated Schottky barrier diode and L-shaped P^+shielding region

A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper.The device features an integrated Schottky barrier diode and an L-shaped P^+shielding region beneath the gate trench and aside one wall of the gate trench(S-TMOS).The integrated Schottky barrier diode works as a free-wheeling diode in reverse recovery and reverse conduction,which significantly reduces reverse recovery charge(Q_(rr))and reverse turn-on voltage(VF).The L-shaped P^+region effectively shields the coupling of gate and drain,resulting in a lower gate–drain capacitance(C_(gd))and date–drain charge(Q_(gd)).Compared with that of conventional SiC trench MOSFET(C-TMOS),the V_F and Q_(rr)of S-TMOS has reduced by 44%and 75%,respectively,with almost the same forward output current and reverse breakdown voltage.Moreover,the S-TMOS reduces Q_(gd)and C_(gd)by 32%and 22%,respectively,in comparison with C-TMOS.

Study of 4H-SiC junction barrier Schottky diode using field guard ring termination

This paper reports that the 4H-SiC Schottky barrier diode, PiN diode and junction barrier Schottky diode terminated by field guard rings are designed, fabricated and characterised. The measurements for forward and reverse characteristics have been done, and by comparison with each other, it shows that junction barrier Schottky diode has a lower reverse current density than that of the Schottky barrier diode and a higher forward drop than that of the PiN diode. High-temperature annealing is presented in this paper as well to figure out an optimised processing. The barrier height of 0.79 eV is formed with Ti in this work, the forward drop for the Schottky diode is 2.1 V, with an ideality factor of 3.2, and junction barrier Schottky diode with blocking voltage higher than 400 V was achieved by using field guard ring termination.

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

4H-SiC junction barrier Schottky （JBS） diodes with a high-temperature annealed resistive termination extension （HARTE） are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm^2 with a total active area of 2.46× 10 ^-3 cm^2. Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250 ℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9× 10^-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.

4H-SiC Schottky barrier diodes with semi-insulating polycrystalline silicon field plate termination

Based on the theoretical analysis of the 4H-SiC Schottky-barrier diodes （SBDs） with field plate termination, 4H-SiC SBD with semi-insulating polycrystalline silicon （SIPOS） FP termination has been fabricated. The relative dielectric con-stant of the SIPOS dielectric first used in 4H-SiC devices is 10.4, which is much higher than that of the SiO2 dielectric, leading to benefitting the performance of devices. The breakdown voltage of the fabricated SBD could reach 1200 V at leak-age current 20 μA, about 70% of the theoretical breakdown voltage. Meanwhile, both of the simulation and experimental results show that the length of the SIPOS FP termination is an important factor for structure design.

Review of gallium oxide based field-effect transistors and Schottky barrier diodes

Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.

Influence of deep defects on electrical properties of Ni/4H-SiC Schottky diode

In this paper, we investigate the influence of deep level defects on the electrical properties of Ni/4H-SiC Schottky diodes by analyzing device current-voltage(I-V) characteristics and deep-level transient spectra(DLTS). Two Schottky barrier heights(SBHs) with different temperature dependences are found in Ni/4 H-SiC Schottky diode above room temperature. DLTS measurements further reveal that two kinds of defects Z_(1/2) and Ti(c)~a are located near the interface between Ni and SiC with the energy levels of E_C-0.67 eV and E_C-0.16 eV respectively. The latter one as the ionized titanium acceptor residing at cubic Si lattice site is thought to be responsible for the low SBH in the localized region of the diode, and therefore inducing the high reverse leakage current of the diode. The experimental results indicate that the Ti(c)~a defect has a strong influence on the electrical and thermal properties of the 4 H-SiC Schottky diode.

Temperature-Dependent Characteristics of GaN Schottky Barrier Diodes with TiN and Ni Anodes

The effect of temperature on the characteristics of gallium nitride (GaN) Schottky barrier diodes (SBDs) with TiN and Ni anodes is evaluated. With increasing the temperature from 25 to 175℃, reduction of the turn-on voltage and increase of the leakage current are observed for both GaN SBDs with TiN and Ni anodes. The performance after thermal treatment shows much better stability for SBDs with Ti N anode, while those with Ni anode change due to more interface states. It is found that the leakage currents of the GaN SBDs with TiN anode are in accord with the thermionic emission model whereas those of the GaN SBDs with Ni anode are much higher than the model. The Silvaco TCAD simulation results show that phonon-assisted tunneling caused by interface states may lead to the instability of electrical properties after thermal treatment, which dominates the leakage currents for GaN SBDs with Ni anode. Compared with GaN SBDs with Ni anode, GaN SBDs with TiN anode are beneficial to the application in microwave power rectification fields due to lower turn-on voltage and better thermal stability.

3300 V高性能混合SiC模块研制

将Si基绝缘栅双极型晶体管(Insulated gate bipolar transistor,IGBT)芯片与SiC结型势垒肖特基二极管芯片按照双开关电路结构排布,开发了一种3 300 V等级混合SiC模块,对其设计方法、封装工艺、仿真、测试结果进行分析,并对标相同规格IGBT模块。混合SiC模块低空洞率焊接满足牵引领域高温度循环周次的要求,冗余式的连跳键合结构可以有效增强功率循环能力。采用双脉冲法测试动态性能,测试结果表明该混合SiC模块反向恢复时间减小了84%,反向恢复电流减小了89.5%,反向恢复能量减小了99%,一次开关产生的总损耗降低了43.3%。混合SiC模块消除了开关过程中电压和电流过冲现象,在高电压、大电流和高频率的应用工况下具有明显的优势。

Modeling,simulations,and optimizations of gallium oxide on gallium-nitride Schottky barrier diodes

With technology computer-aided design(TCAD)simulation software,we design a new structure of gallium oxide on gallium-nitride Schottky barrier diode(SBD).The parameters of gallium oxide are defined as new material parameters in the material library,and the SBD turn-on and breakdown behavior are simulated.The simulation results reveal that this new structure has a larger turn-on current than Ga2O3 SBD and a larger breakdown voltage than Ga N SBD.Also,to solve the lattice mismatch problem in the real epitaxy,we add a Zn O layer as a transition layer.The simulations show that the device still has good properties after adding this layer.

4H-SiC SBD和JBS退火研究

在4H-SiC外延材料上制备了SBD和JBS器件,研究并分析了退火温度对这两种器件正反向特性的影响。结果表明,低于350℃退火可同时提高SBD和JBS的正反向特性。当退火温度高于350℃时,二者的正向特性都出现退化,SBD退化较JBS更为严重。JBS阻断电压随退火温度升高而增大,在退火温度高于450℃时增加趋势变缓。SBD阻断电压随退火温度升高先升后降,在500℃退火时达到一个最大值。可见一定程度的退火有助于提高4H-SiCSBD和JBS器件的正反向特性,但须考虑其对正反向特性的不同影响。综合而言,退火优化后JBS优于SBD器件性能。

SiC SBD与MOSFET温度传感器的特性

对SiC肖特基势垒二极管(SBD)和金属氧化物半导体场效应晶体管(MOSFET)温度传感器进行了理论分析与测试。基于器件的工作原理,分析了影响传感器灵敏度的因素,SiC SBD温度传感器的灵敏度主要受理想因子的影响,而SiC MOSFET温度传感器的灵敏度主要受栅氧化层厚度等因素的影响。仿真结果表明,SiC MOSFET温度传感器的灵敏度随偏置电流下降或者栅氧化层厚度增加而上升。实测结果表明,两种传感器的最高工作温度均超过400℃,其中SiC SBD温度传感器在较宽的温度范围实现了更好的线性度,而SiC MOSFET温度传感器的灵敏度更高。研究结果表明,SiC MOSFET作为高温温度传感器具有灵敏度高和设计灵活度高等方面的显著优势。

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SiC SBD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。

Fabrications and characterizations of high performance 1.2 kV,3.3 kV, and 5.0 kV class 4H–SiC power SBDs

In this paper, 1.2 kV, 3.3 kV, and 5.0 kV class 4H-SiC power Schottky barrier diodes （SBDs） are fabricated with three N-type drift layer thickness values of 10 μm, 30μm, and 50 μm, respectively. The avalanche breakdown capabilities, static and transient characteristics of the fabricated devices are measured in detail and compared with the theoretical pre- dictions. It is found that the experimental results match well with the theoretical calculation results and are very close to the 4H-SiC theoretical limit line. The best achieved breakdown voltages （BVs） of the diodes on the 10 p.m, 30 m, and 50 -tm epilayers are 1400 V, 3320 V, and 5200 V, respectively. Differential specific-on resistances （Ron-sp） are 2.1 m--cm2, 7.34 mO. cm2, and 30.3 m-. cm2, respectively.

4H-SiC SP-MPS二极管迅回效应的仿真研究

为了抑制4H-SiC MPS二极管的迅回效应,在传统结构的肖特基结下方引入P-轻掺杂区形成SP-MPS结构。给出简化电阻模型和等效电路图分析MPS二极管的正向导通特性,仿真了肖特基区宽度、P+区结深及P-区深度等关键参数对迅回效应的影响。研究结果表明,减小肖特基区宽度、增加P+区结深均可有效抑制迅回效应。SPMPS结构通过添加P-轻掺杂区来调整肖特基势垒高度进而控制转折电压的大小,增加P-区深度对迅回效应具有抑制作用,但与P-区掺杂浓度基本无关。对比传统MPS结构,在P-区深度为0.25μm、掺杂浓度为1×10^(17)cm^(-3)的条件下,SP-MPS结构的肖特基势垒高度增加了35.7%,转折电压降低了73.2%,明显改善迅回效应对MPS二极管正向特性的影响。

宽禁带SiC肖特基势垒二极管的研制

采用微电子平面工艺 ,高真空电子束蒸发金属Ni作肖特基接触 ,多层金属Ni、Ti、Ag合金作欧姆接触 ,SiO2 绝缘环隔离减小高压电场集边效应等技术 ,制作出Ni/4H SiC肖特基势垒二极管 (SBD) .该器件在室温下反向击穿电压大于 450V ,对应漏电流为 6× 1 0 -6 A .并对实验结果进行分析模拟 ,理想因子为 1 .73 ,肖特基势垒高度为 1 .2 5V ,实验表明 ,该器件具有较好的正向整流特性和较小的反向漏电流 .

MISiC氢敏传感器物理模型及特性模拟

分析了金属 绝缘体 SiC(MISiC)肖特基势垒二极管 (SBD)气体传感器的响应机理 ,将SBD热电子发射理论和氢吸附 解吸理论相结合 ,通过考虑势垒高度调制效应以及理想因子随外界条件的变化 ,建立了MISiCSBD气体传感器物理模型 ,模拟结果与实验十分吻合。采用此模型 ,分析了器件特性与绝缘层厚度的关系 ,并在灵敏度、可靠性和工作电流 /电流分辨率诸因素之间其进行了优化设计 ,对于 30 0℃左右的高温应用 ,确定出最佳绝缘层厚度为2～ 2 .3nm。