电子辐照下的SiC少子寿命退化模型

从理论上对电子辐照在4H-SiC中引入的缺陷数量和各种缺陷能级进行了分析.结果表明,EH6和EH7缺陷能级在4H-SiC中起着有效复合中心的作用.采用SRH模型来估计电子辐照下4H-SiC的少子寿命,并给出了电子辐照下4H-SiC少子寿命损伤系数的模型.结合具体的测量条件,证明了这个模型是合理的.辐照电子对Si、GaAs和4H-SiC产生的不同影响展示了在高空、高辐照条件下 SiC存在着优势.     

Si(100)面上3C-SiC的生长

１０００℃下用Ｓｉ２Ｈ６和Ｃ２Ｈ４在Ｓｉ（１００）面上用气源分子束外延进行了ＳｉＣ的生长,Ｘ射线双晶衍射和ＨＲＥＥＤ表明外延层为３Ｃ－ＳｉＣ单晶;俄歇电子谱分析其中的Ｓｉ／Ｃ约为１．６．用Ｎｏ－ｍａｒｓｋｉ光学显微镜观察,其表面存在类似四边形的缺陷;与不同温度,不同Ｃ２Ｈ４流量下Ｓｉ衬底碳化形成的碳化层表面进行了比较,分析了缺陷形成的原因．     

1．8GHz下功率密度为2．8W／mm的4H－SiC MES FET

１．８ＧＨｚ下功率密度为２．８Ｗ／ｍｍ的４Ｈ－ＳｉＣＭＥＳＦＥＴ据《ＩＥＥＥＥ．Ｄ．Ｌ．》第１５卷第１０期报道，ＣｈａｒｌｅｓＥ．Ｗｅｉｔｚｅｌ等已研制成一种４Ｈ－ＳｉＣＭＥＳＦＥＴ。采用４Ｈ－ＳｉＣ是由于它比６Ｈ－ＳｉＣ高出两倍的电子迁移率。器件的...     

Ge_(0.4)Si_(0.6)/Si多量子阱与Ge/Si短周期超晶格样品中的深中心

用深能级瞬态谱（ＤＬＴＳ）研究了分子束外延生长的Ｇｅ０．４Ｓｉ０．６／Ｓｉ多量子阱与Ｇｅ／Ｓｉ应变超晶格样品中深能级中心的性质．在两种样品中都观测到两个多数载流子中心和一个少数载流子中心．在Ｇｅ０．４Ｓｉ０．６／Ｓｉ多量子阱样品中深中心Ｅ２的能级位置为ＥＣ－０．３０ｅＶ,Ｅ３的能级位置为ＥＣ－０．２２ｅＶ．并且在正向注入下随着Ｅ２峰的消失观测到一个少数载流子峰ＳＨ１,其能级位置为ＥＶ＋０．６８ｅＶ．在Ｇｅ／Ｓｉ应变超晶格中,深中心Ｈ１的能级位置为ＥＶ＋０．４４ｅＶ,深中心Ｈ２的能级位置为ＥＶ＋０．２４ｅＶ     

Ge0.4Si0.6／Si多量子阱与Ｇe／Si周期超晶格样品中的深中心

用深能级瞬态谱（ＤＬＴＳ）研究了分子束外延生长的Ｇｅ０．４Ｓｉ０．６／Ｓｉ多量子阱与Ｇｅ／Ｓｉ为超晶格样品中深能级中心的性质,在种样品中都观测到两个多数载流子中心和一个少数载流子中心,在Ｇｅ０．４Ｓｉ０．６／Ｓｉ多量子阱样品深中心Ｅ２的能级位置为ＥＣ－０．３０ｅＶ,Ｅ３的能级位置为Ｅｃ－０．２２ｅＶ,并且在正向注入下随着Ｅ２峰的消失到一个少数载流子峰ＳＨ１,其能级位置为ＥＶ＋０．６８ｅＶ,在Ｇｅ／     

中子辐照下的6H-SiCpn结电特性分析

用中子辐照在６Ｈ－ＳｉＣｐｎ结中引入的复合中心和深能级陷阱解释了ＳｉＣｐｎ结辐照后电特性退化的现象,并推导了辐照后ＳｉＣｐｎ结理想因子与外加电压的关系,给出了ＳｉＣｐｎ结中子辐照电特性退化的模型,模拟结果和实验数据的对比说明关于ＳｉＣｐｎ结电特性退化的理论解释是正确的。     

电子辐照CZ—Si单晶的深能级

常熳下用剂量为４×１０＾１５电子／ｃｍ＾２的１．８ＭｅＶ电子束对ＣＺ－Ｓｉ单晶制成的ｐ＾＋ｎ二极管进行了辐照，采用能级瞬态谱技术在该样品中观察到４个深能级，并对其形成原因进行了讨论。     

6H－SiC反型沟道和掩埋沟道MOS器件的特性

介绍了在宽禁带半导体６Ｈ－ＳｉＣ材料上制作的反型沟道和掩埋沟道栅控二极管及ＭＯＳＦＥＴ。器件的制作采用了热氧化和离子注入技术。因为６Ｈ－ＳｉＣ禁带宽度为３ｅＶ，用ＭＯＳ电容很难测量表面态，故利用栅控二极管在室温条件下来测量表面态。反型沟道器件中电子有效迁移率为２０ｃｍ２／Ｖ．ｓ，而掩埋沟道ＭＯＳＦＥＴ沟道中的体电子迁移率为１８０ｃｍ２／Ｖ．ｓ。掩埋沟道晶体管是第一只ＳｉＣ离子注入沟道器件，也是第一只６Ｈ－ＳｉＣ掩埋沟道ＭＯＳＦＥＴ。     

SiC器件──物理与数值模拟

从文献中摘出了６Ｈ碳化硅（６Ｈ～ＳｉＣ）的重要材料参数并应用到２－Ｄ器件模拟程序ＰＩＳＣＥＳ和ＢＲＥＡＫＤＯＷＮ及１－Ｄ程序ＯＳＳＩ中。６Ｈ－ＳｉＣｐ－ｎ结的模拟揭示了由于反向电流密度较低的缘故相应器件在高达１０００Ｋ温度下应用的可能性。６Ｈ－ＳｉＣ１２００Ｖｐ－ｎ￣（－）－ｎ￣（＋）二极管与相应硅（Ｓｉ）二极管的比较说明６Ｈ－ＳｉＣ二极管开关性能较高，同时由于６Ｈ－ＳｉＣ　ｐ－ｎ结内建电压较高，其正向功率损耗比Ｓｉ略高。这种缺点可用６Ｈ－ＳｉＣ肖特基二极管克服。Ｓｉ、３Ｃ－ＳｉＣ和６Ｈ－ＳｉＣ垂直功率ＭＯＳＦＥＴ的开态电阻通过解析计算进行了比较。在室温下，这种ＳｉＣＭＯＳＦＥＴ的开态电阻低于０．１Ωｃｍ￣２，可在高达５０００Ｖ阻塞能力下工作，而ＳｉＭＯＳＦＥＴ则限于５００Ｖ以下。这一点通过用ＰＩＳＣＥＳ计算６Ｈ－ＳｉＣ１２００ＶＭＯＳ－ＦＥＴ的特性得以验证。在低于２００Ｖ的电压区，由于硅的迁移率较高且阈值电压较低，故性能更优良。在上述的６Ｈ－ＳｉＣＭＯＳＦＥＴ的栅氧化层和用于钝化平面结的场板氧化层中存在着大约４×１０￣６Ｖ／ｃｍ的电场。为了研究ＳｉＣ器件的高频性能，提出了６Ｈ－ＳｉＣ发射极的异质双极晶体管?     

电子辐照CZ－Si单晶的深能级

常温下用剂量为４×１０（１５）电子／ｃｍ２的１．８ＭｅＶ电子束对ＣＺ－Ｓｉ单晶制成的ｐ＋ｎ二极管进行了辐照，采用深能级瞬态谱技术（ＤＬＴＳ）在该样品中观察到４个深能级，并对其形成原因进行了讨论。     

中子辐照硅中少子寿命的衰退(英文)

Disordered regions(DR) produced by neutron irradiation are highly effective for the degradation of minority carrier lifetime in silicon. In this paper we analyze the properties of the DR in detail, calculate the occupancies of defect states and the bending height of the energy band by means of the effectively generalizing of Schokly-Read-Hall statistical recombination theory to the DR, and present the self-consistent formulas for calculating degradation of minority carrier lifetime in the region, including the influences of defect concentration, band bending height, quasi -Fermi level as well as excess carrier density on the minority carrier lifetime. Finally, we make a comparision between the calculation results from the disordered region model and the point defect model and experimental results with detailed discussions.     

The effect of ionization and displacement damage on minority carrier lifetime

Based on 1 MeV electrons and 40 MeV Si ion irradiations, the contribution of ionization and displacement damage to the decrease in the minority carrier lifetime of gate controlled lateral PNP (GLPNP) transistors is investigated by gate sweeping (GS) technique. Molecular hydrogen is employed to increase the ionization radiation sensitivity and help to understand the relationship between the minority carrier lifetime and ionization damage. Experimental results show that 1 MeV electrons mainly induce ionization damage to GLPNP transistors, 40 MeV Si ions primarily produce displacement defects in silicon bulk. For 40 MeV Si ions, with increasing the irradiation dose, the densities of interface trap and oxide charge are almost no change, the minority carrier lifetime obviously decreases. The decrease of the minority carrier lifetime is due to bulk traps induce by 40 MeV Si ions. For 1 MeV electrons, with increasing the irradiation dose, the densities of interface trap and oxide charge for the GLPNP with and without soaked in H₂ increase, and the minority carrier lifetime decreases. Compared with the GLPNP transistors without soaking in H₂, the density of the interface traps the irradiated GLPNP transistors by 1 MeV electrons and soaked in H₂ are larger and the minority carrier lifetime is lower. Therefore, both ionization and displacement damage can induce the decreases in the minority carrier lifetime including bulk minority carrier lifetime and surface minority carrier lifetime.     

Electron irradiation induced recombination centers in silicon-minority carrier lifetime control

Recombination centers introduced in silicon p⁺-n-n⁺structures by irradiation with 2-MeV electrons are studied by measuring minority carrier lifetime and annealing kinetics. The approximate location of these recombination centers in the forbidden gap and their densities are obtained by the thermally stimulated current method. The results identify one defect as a divacancy with an energy level of Ev+ 0.26 eV. Possible identities of other deep levels are discussed. The technique of minority carrier lifetime control by electron irradiation has been developed into a reliable manufacturing process for power devices.     

中子辐照损伤区对硅少数载流子寿命的影响

中子辐照在半导体硅晶体中形成无序区,使其电学性能受到严重影响.本文根据无序区基本特征,系统分析中子辐照对少数载流子寿命影响的过程,给出了一个完整自洽的计算表达式;理论计算了材料掺杂浓度、无序区辐照缺陷分布态,以及载流子注入量等参量对少数载流子寿命的影响.最后,将计算结果与点缺陷模型、及实验测量数量进行比较和讨论.     

A high-temperature radiation-resistant rectifier based on p<Superscript>+</Superscript>-n junctions in 4H-SiC ion-implanted with aluminum

A combination of a high-dose (5 s- 10¹⁶ cm^-2) implantation of Al ions into epitaxial n-type 4H SiC layers grown by chemical deposition from th e vapor phase and rapid (15 s) thermal annealing at 1700–1750°C has been used to form layers with a rectangular impurity profile according to the mechanism of solid-phase epitaxial crystallization. The combined effects of enhanced diffusion of radiation defects after implantation and gettering of defects during annealing bring about an improvement in the quality of the initial material, which ensures an increase in the diffusion length of the minority charge carriers by several times. Metastable states annealed within different temperature ranges are formed in SiC under the effect of irradiation with various particles. Low-temperature annealing of radiation defects increases the radiation and temporal lifetime of devices under irradiation. High-temperature annealing of radiation defects makes it possible to vary the lifetime of nonequilibrium charge carriers, i.e, vary the frequency range of devices. The radiation resistance of SiC-based devices increases as the operation temperature is increased to 500°C.     

微波光电导衰减法测量N型4H-SiC少数载流子寿命

为了更好地了解N型4H-SiC的电学特性,评价其晶体质量,采用激光技术和微波光电导作为非接触、非破坏性测量半导体特性的一种工具,描述了其测试原理和实验装置,并讨论了不同的激发强度下,其少数载流子寿命的变化。结果表明,改变入射激光能量(即光子注入水平),样品电压峰值与激发强度成正比,对其载流子寿命几乎没有影响。该方法能方便快捷地测量载流子的寿命,对SiC材料性能的研究具有重要意义。     

双基区大功率快恢复二极管的研究

提出了在采用VB=94ρ0n.7数学模型设计双基区p+pinn+结构快速软恢复FRD大功率二极管结构参数中引入η=Wi/Xm=0.25数学模型的方法。采用Si片扩铂和电子辐照共同控制基区少子寿命及分布,并利用该设计方法对ZKR1 000 A/2 600 V结构参数进行了优化设计。对设计参数进行了实验验证,结果表明,器件参数满足设计指标,达到国外同类产品水平。说明该设计方法及各种参数的选取是正确的,寿命控制技术是有效的。为p+pinn+结构二极管设计与制造提供了一种具有重要的指导意义和参考价值的新方法。     

高阻NTD-FZ-Si-P~+n结电子辐照缺陷能级N_2气氛的退火特性

报导了高阻（８１～１１０Ω·ｃｍ）ＮＴＤ ＦＺ Ｓｉ Ｐ＋ｎ结中电子辐照缺陷态的退火特性。在Ｎ２气氛保护下进行等时、等温退火,测量了它们的ＤＬＴＳ谱和相应的少数载流子寿命,并对结果进行了分析讨论。     

Neutron irradiation of insulated gate field effect transistors

Insulated gate field effect transistors and polysilicon-gated capacitors were irradiated with fast (10 keV <E < 2 MeV) neutrons. As expected, damage to the bulk silicon was detected as a degradation in the minority carrier lifetime. Optically assisted electron injection was employed for the first time to examine neutral electron trap and fixed positive charge generation in the gate insulator of the devices. While fixed positive charge densities of ≤6 x 10¹⁰ cm⁻² were detected, little or no neutral electron trap generation was observed. The small density of coulombic defects observed in the insulator could be accounted for fully by the known flux of gamma rays associated with the neutron irradiation process. This indicates that fast neutrons passing through a thin gate oxide do not produce significant amounts of damage in the oxide. Somewhat surprisingly, it was found that 1.5 keV X-rays created similar lifetime degradation effects in the bulk silicon, as did fast neutrons, even though this photon energy is not believed to be capable of producing bulk damage in the form of atom displacement in either the semiconductor or the insulator. The minority carrier lifetime of the silicon could be restored to initial values following either neutron or x-ray exposure by annealing in H₂ for 30 min at 400° C.     

Electron beam-induced current investigation of GaN Schottky diode

In this article, we report the electron beam-induced current (EBIC) measurements in a GaN Schottky diode performed in the line-scan configuration. A theoretical model with an extended generation source was used to accurately extract some minority carrier transport properties of the unintentionally doped n-GaN layer. The minority hole diffusion length is found to increase from ∼0.35 μm near the junction to ∼1.74 μm at the bulk regions. This change is attributed to an increase of the carrier lifetime caused by the polarization effects, which are preponderant in this component. For depth distances exceeding 0.65 μm, it is shown that the measured current is produced by the reabsorption recombination radiation process. This corresponds to an absorption coefficient of 0.178 μm⁻¹, in good agreement with the optical absorption measurement.