Fabrication and characterization of vertical GaN Schottky barrier diodes with boron-implanted termination

The vertical GaN-on-GaN Schottky barrier diode with boron-implanted termination was fabricated and characterized.Compared with the Schottky barrier diode(SBD)without boron-implanted termination,this SBD effectively improved the breakdown voltage from 189 V to 585 V and significantly reduced the reverse leakage current by 10^5 times.In addition,a high Ion/Ioff ratio of ~10^8 was achieved by the boron-implanted technology.We used Technology Computer Aided Design(TCAD)to analyze reasons for the improved performance of the SBD with boron-implanted termination.The improved performance of diodes may be attributed to that B+could confine free carriers to suppress electron field crowding at the edge of the diode,which could improve the breakdown voltage and suppress the reverse leakage current.

Effect of anode area on the sensing mechanism of vertical GaN Schottky barrier diode temperature sensor

Effect of anode area on temperature sensing ability is investigated for a vertical GaN Schottky-barrier-diode sensor.The current-voltage-temperature characteristics are comparable to each other for Schottky barrier diodes with different anode areas,excepting the series resistance.In the sub-threshold region,the contribution of series resistance on the sensitivity can be ignored due to the relatively small current.The sensitivity is dominated by the current density.A large anode area is helpful for enhancing the sensitivity at the same current level.In the fully turn-on region,the contribution of series resistance dominates the sensitivity.Unfortunately,a large series resistance degrades the temperature error and linearity,implying that a larger anode area will help to decrease the series resistance and to improve the sensing ability.

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.

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.

Vertical GaN Shottky barrier diode with thermally stable TiN anode

Vertical GaN Schottky barrier diodes with Ti N anodes were fabricated to investigate the electrical performance. The turn-on voltage and specific on-resistance of diodes are deduced to be approximately 0.41 V and 0.98 mΩ·cm2, respectively.The current-voltage curves show rectifying characteristics under different temperatures from 25℃ to 200℃, implying a good thermal stability of Ti N/Ga N contact. The low-frequency noise follows a 1/f behavior due to the multiple traps and/or barrier inhomogeneous at Ti N/Ga N interface. The trapping/de-trapping between traps and Fermi level causes the slight capacitance dispersion under reverse voltage.

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.

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。

GaN基SBD功率器件研究进展

作为第三代宽禁带半导体器件,GaN基肖特基势垒二极管(SBD)功率器件具有耐高温、耐高压和导通电阻小等优良特性,在功率器件方面具有显著的优势。概述了基于功率应用的GaN SBD功率器件的研究进展。根据器件结构,介绍了基于材料特性的GaN SBD和基于AlGaN/GaN异质结界面特性的GaN异质结SBD。根据器件结构对开启电压的影响,对不同阳极结构器件进行了详细的介绍。阐述了不同的肖特基金属的电学特性和热稳定性。分析了表面处理,包括表面清洗、表面等离子体处理和表面钝化对器件漏电流的影响。介绍了终端保护技术,尤其是场板技术对击穿电压的影响。最后探讨了GaN基SBD功率器件未来的发展趋势。

AlGaN/GaN SBD的正向导通特性研究

主要研究了横向AlGaN/GaN异质结肖特基势垒二极管(简称SBD)的正向导通特性,设计制备了基于蓝宝石衬底和硅衬底的不同器件结构的AlGaN/GaN SBD器件。测量结果表明,通过适当改变肖特基-欧姆电极布局,以及在导电衬底上施加相应的偏压,可以有效改善器件的正向导通特性。实验所制备的肖特基电极半径为120μm、肖特基-欧姆电极间距为25μm的基于Al2O3衬底的AlGaN/GaN SBD器件,实现了正向导通电流0.05A@2V(Ron=9.13mΩ·cm2)、反向饱和漏电流为10-6 A的性能。对制备的硅基AlGaN/GaN SBD器件的测试发现,通过外加衬底偏压能够有效改善其正向导通特性。

一种提高ESD性能的高压SBD器件结构研究

提出了一种新型SBD器件结构,并应用于高压SBD产品的研制。该结构通过在肖特基势垒区的硅表面增加一层表面缓冲掺杂层(Improved Surface Buffer Dope),将高压SBD的击穿点从常规结构的PN结保护环区域转移到平坦的肖特基势垒区,从根本上提高了器件的反向静电放电(ESD)和浪涌冲击能力。经流片验证,采用该结构的10A150VSBD产品和10A200VSBD产品均通过了反向静电放电(HBM模式)8kV的考核,达到目前业界领先水平。该结构工艺实现简单,可以应用于100V以上SBD的批量生产。

SBD势垒高度的影响因素

针对硅材料的肖特基势垒二极管(Schottky Barrier Diode,简称SBD)的击穿电压普遍很低,严重影响其实际应用的问题,采用实验与理论分析相结合的方式,着重于表面态、界面层对势垒高度的影响进行研究.提取了三个重要参数:表面态密度D_i、界面层电容密度C_i和表面态中性能级Φ_0.结果表明,势垒高度的高低强烈依赖于这三个特性参数的大小.

AlGaN/GaN非凹槽混合阳极SBD射频性能及建模

基于大功率微波输能的需求,制备了新型AlGaN/GaN非凹槽混合阳极肖特基势垒二极管(SBD)。对新型结构的器件进行了小信号建模,可用于微波输能电路设计。通过开路、短路去嵌结构法从小信号S参数中提取了器件的寄生电容、电感和电阻,结合去嵌后的S参数与直流I-V、C-V特性曲线提取了器件的本征参数。综合寄生和本征参数建立了器件的小信号模型,将模型仿真结果与器件的实测结果进行了对比,同时引入误差因子评估了模型的准确度。结果表明,在0.1~10 GHz内,回波损耗相对误差小于4.1%,插入损耗相对误差小于3.7%,验证了所提出模型的可行性和准确性。

基于太赫兹单片集成电路的560 GHz次谐波混频器设计

基于太赫兹单片集成技术,设计并加工了一款560 GHz次谐波混频器。建立了二极管的三维电磁模型进行全波仿真,并结合二极管SPICE参数模型,获得了包括寄生参数和本征参数的二极管完整模型。基于半分部−半整体设计法对电路进行了仿真优化,既具有灵活性,电路整体尺寸也较小。整体电路设计在3μm厚的GaAs薄膜上,有效地抑制了高次模的传输,同时降低传输损耗。通过铺大面积的梁氏引线提供足够的应力支撑,提高电路的稳定性。实验结果表明:本振驱动功率3 mW下,混频器在520~600 GHz射频范围内变频损耗小于11 dB。

金刚石硼掺杂准垂直肖特基二极管特性研究

金刚石是超宽禁带半导体材料的典型代表,因其优异的材料特性,在高温、高频、大功率微波和电力电子器件应用中有着显著的优势。金刚石体掺杂p型二极管由于工艺简单、并且有望发挥出金刚石击穿场强高的特性。采用微波等离子体化学气相沉积设备实现了单晶金刚石外延过程中硼掺杂浓度的调控,在金刚石本征衬底上制备出p^(-)/p^(+)结构的金刚石外延层,掺杂浓度分别为1018 cm^(-3)和1020 cm^(-3)。进而采用该结构制备了金刚石准垂直结构的肖特基二极管器件。测试结果表明,器件正向导通电阻为90 mΩ·cm^(2),开启电压约为-1.68 V,反向击穿场强为2.4 MV/cm,归一化后的电流密度为53.05 A/cm^(2)。计算得该器件中漂移层的载流子浓度为1.16×10^(18)cm^(-3)。

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。

1200V 40A碳化硅肖特基二极管设计

设计并实现了一种阻断电压为1 200V、正向电流40A的碳化硅(SiC)肖特基势垒二极管(SBD)。采用有限元仿真的方法对器件的有源区和终端保护参数进行了优化。器件采用10μm厚度掺杂浓度为6E15cm-3的外延材料,终端保护采用浮空场限制环。正向电压1.75V时,导通电流达到40A。

N_2O氧化制备MISiC氢传感器的响应特性分析

采用N2 O氮化氧化技术制备氮化氧化物作为绝缘层制备金属 -绝缘体 -SiC(MISiC)肖特基势垒二极管(SBD)气体传感器的技术 ,对传感器的响应特性进行了研究。实验结果表明 ,N2 O工艺能明显改善栅绝缘层和衬底之间的界面特性从而提高传感器的性能 ,可在高温 (如 30 0℃ )等恶劣环境下长期可靠的工作 ,且适当增加绝缘层厚度有助于传感器灵敏度和可靠性的改进。

SiC肖特基势垒二极管的反向特性

在n型4H-SiC衬底上的n型同质外延层的Si面制备了纵向肖特基势垒二极管(SBD),研究了场板、场限环及其复合结构等不同终端截止结构对于反向阻断电压与反向泄漏电流的影响。场板(FP)结构有利于提高反向阻断电压,减小反向泄漏电流。当场板长度从5μm变化到25μm,反向阻断电压随着场板长度的增加而增加。SiO2厚度对于反向阻断电压有重要的影响,当厚度为0.5μm,即大约为外延层厚度的1/20时,可以得到较大的反向阻断电压。当场限环的离子注入区域宽度从10μm变化到70μm,反向阻断电压也随之增加。FLR和FP复合结构对于改善反向阻断电压以及反向泄漏电流都有作用,同时反向阻断电压对于场板长度不再敏感。采用复合结构,在10μA反向泄漏电流下最高阻断电压达到1 300V。讨论了离子注入剂量对于反向阻断电压的影响,注入离子剂量和反向电压的关系表明SBD结构不同于传统PIN结构的要求。当采用大约为150%理想剂量的注入剂量时才可达到最高的反向阻断电压而不是其他报道的75%理想剂量,此时的注入剂量远高于PIN结构器件所需的注入剂量。