不同偏置下CCD器件γ射线及质子辐射研究

电荷耦合器件(CCD)是用于空间光电系统可见光成像的图像传感器,在空间应用环境下受辐射效应作用导致CCD性能退化甚至失效。对于CCD空间辐射效应的地面模拟试验研究,辐照试验中CCD采用合适的偏置条件是分析其空间辐射损伤的必要措施。由于CCD对质子辐照导致的电离总剂量效应和位移损伤效应均非常敏感,因此针对CCD空间应用面临的电离总剂量效应和位移损伤效应威胁,开展不同辐照偏置下CCD的辐射效应及损伤机理研究。针对一款国产埋沟CCD器件,开展不同偏置条件下的γ射线和质子辐照试验,获得了CCD的暗电流、光谱响应等辐射敏感参数的电离总剂量效应,位移损伤效应退化规律以及辐照偏置对CCD辐射效应的影响机制。研究表明,γ射线辐照下CCD的偏置产生重要影响,质子辐照下没有明显的偏置效应。根据CCD结构和辐照后的退火试验结果,对CCD的辐射效应损伤机理进行分析。     

CMOS有源像素图像传感器的辐照损伤效应

互补金属氧化物半导体(CMOS)有源像素(APS)图像传感器作为光电成像系统的核心器件,被广泛应用在空间辐射或核辐射环境中,辐照损伤是导致其性能退化,甚至功能失效的主要原因之一。阐述了不同辐射粒子或射线辐照损伤诱发CMOS APS图像传感器产生位移效应、总剂量效应和单粒子效应的损伤物理机制。综述和分析了辐照损伤诱发CMOS APS图像传感器暗信号增大、量子效率减小、饱和输出电压减小、噪声增大以及暗信号尖峰和随机电码信号(RTS)产生的实验规律和损伤机理。归纳并提出了CMOS APS图像传感器辐照损伤效应研究亟待解决的问题。     

850 nm垂直腔面发射激光器的辐射效应

为了探究850 nm高速垂直腔面发射激光器（Vertical-Cavity Surface-Emitting Laser,VCSEL）在空间辐射环境中的退化规律与机制,开展了10 MeV质子和γ-射线辐照实验,获得了光功率和阈值电流退化规律,分析了辐射导致VCSEL参数退化的物理机理,此外,还开展了236 h的电注入退火研究。研究结果表明:VCSEL对γ射线导致的总剂量效应不敏感,且在一定剂量范围内光电特性由于沉积能量促进了量子阱界面附近的晶体有序而产生了一定程度的恢复:但是在质子辐照下,VCSEL的阈值电流和外量子效率发生了不同程度的退化,计算获得阈值电流损伤因子为1.468×10?15 cm2/p。经过20 mA注入增强退火后,阈值电流恢复了20%,25 mA注入电流下,光输出功率恢复了10%。阈值电流和外量子效率的退化归因于质子辐照引入的非辐射复合中心。这些实验结果为VCSEL及包含VCSEL的数据通信与仪器的系统在恶劣空间辐射环境下的应用提供支持。     

半导体激光器辐照损伤效应实验研究进展

半导体激光器(LD)工作在空间辐射或核辐射环境中时,会受到辐照损伤的影响而导致器件性能退化。文章回顾了不同时期研制的LD(从早期的GaAs LD到量子阱LD和量子点LD)在辐照效应实验方面的研究进展,梳理了国际上开展不同辐射粒子或射线(质子、中子、电子、伽马射线)诱发LD辐射敏感参数退化的实验规律,分析总结了当前LD辐照效应实验方法研究中亟待解决的关键技术问题,为今后深入开展LD的辐照效应实验方法、退化规律、损伤机理及抗辐射加固技术研究提供理论指导和实验技术支持。     

电子辐照深亚微米MOS晶体管的总剂量效应

为了研究电子辐照导致CCD参数退化的损伤机理,以及CCD内不同沟道宽长比的NMOSFET的辐射效应,将与CCD同时流片的两种不同沟道宽长比的深亚微米NMOSFET进行电子辐照实验。分析了电子辐照导致NMOSFET阈值电压和饱和电流退化的情况,以及器件的辐射损伤敏感性。实验结果表明,电子辐照导致两种NMOSFET器件的参数退化情况以及辐射损伤敏感性类似。导致器件参数退化的主要原因是界面陷阱电荷,同时氧化物陷阱电荷表现出了一定的竞争关系。实验结果为研究CCD电子辐照导致的辐射效应提供了基础数据支持。     

CMOS图像传感器辐射敏感参数测试电路设计及试验验证

以航天领域广泛应用的CMV4000型CMOS图像传感器(CIS)为研究对象,通过开展CIS辐射敏感参数测试电路设计,将CIS辐照电路板与测试电路板中FPGA数据采集及传输板分离,辐照电路板与测试电路板通过接插口通信,从而实现开展辐照试验时对FPGA数据采集部分进行辐射屏蔽防护,避免FPGA数据采集板受到辐射影响。开展了CIS测试电路中的电源模块、数据采集、存储模块、外围电路等设计及PCB版图的布局布线设计。采用Verilog HDL硬件描述语言对各个功能模块进行驱动时序设计,实现CIS辐射敏感参数测试功能。通过开展CMV4000型CIS ⁶⁰Co γ射线辐照试验,分析了平均暗信号、暗信号非均匀性、暗信号分布等辐射敏感参数随总剂量增大的退化规律,验证了CIS辐射敏感参数测试系统的可靠性。     

CMOS图像传感器辐射损伤导致星敏感器性能退化机理

为了分析恶劣空间辐射环境导致星敏感器性能退化、姿态测量精度降低的原因,深入研究了辐射环境下互补金属氧化物半导体（Complementary Metal Oxide Semiconductor, CMOS）图像传感器辐射损伤对星敏感器性能退化的影响。该方法通过建立空间辐射和CMOS图像传感器辐射损伤敏感参数、星敏感器性能参数之间的相关性,揭示了CMOS 图像传感器器件参数退化到星敏感器系统参数退化的传递机制。60Co-γ辐照试验表明:辐照后,系统信噪比的降低导致星敏感器星等探测灵敏度的降低,信噪比是联系CMOS图像传感器和星敏感器系统之间的桥梁。质子辐照试验表明:当辐照注量大于3.68×1010 p/cm2时,已无法正确提取星点质心。该研究结果为星敏感器在轨姿态测量误差预测和修正技术的研究奠定了一定的基础,更可以为高精度星敏感器的设计提供一定的理论依据。     

CCD辐射损伤效应及加固技术研究进展

综述了电荷耦合器件(CCD)在空间环境和核辐射领域中的辐射效应研究进展;阐述了不同粒子辐照CCD的损伤效应机理及暗电流、平带电压和电荷转移效率等敏感参数的退化机制;从制造工艺、器件结构、工作模式等方面介绍了CCD抗辐射加固技术;分析了CCD辐射效应研究的发展趋势。     

CMOS图像传感器抗电离辐射加固技术研究

太空环境中的电离辐射会导致CMOS图像传感器性能退化,甚至造成永久性损毁。文章对CMOS图像传感器抗电离辐射加固技术进行了研究,从版图设计、电路设计等方面提出相应的抗辐射策略,并进行了总剂量和单粒子试验。试验结果表明,采用抗辐射加固技术设计制作的CMOS图像传感器具备抗总剂量和单粒子辐射能力,当总剂量达到100krad(Si)、单粒子辐射总注量达到1×10⁷p/cm²时,器件的关键指标变化符合预期要求。     

深亚微米N沟道MOS晶体管的总剂量效应

为了研究深亚微米工艺CCD的辐射效应特性,了解因器件特征尺寸变小引入的新效应,对0.18 μm商用工艺线上流片的不同沟道宽长比的N型沟道MOSFET器件进行了⁶⁰Co-γ射线辐照实验,这些NMOSFET与CCD内的MOSFET结构相同。分析了辐照后由于总剂量效应导致的NMOSFET参数退化情况以及参数的常温和高温退火行为。实验结果表明,深亚微米工艺器件的辐射耐受性相比大尺寸器件明显增强,不同沟道宽长比的器件表现出的总剂量效应差异显示了器件具有明显的窄沟效应,界面陷阱电荷在新型器件的总剂量效应中起主导作用。研究结果为大面阵CCD的辐射效应研究和辐射加固设计提供了理论支持。     

Study of proton irradiation effects on AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) were exposed to 3 MeV protons at fluences of 6 × 10¹³, 4 × 10¹⁴ and 1 × 10¹⁵ protons/cm². The drain saturation currents decreased by 20% and the maximum transconductance decreased by 5% at the highest fluence. As the fluence increased, the threshold voltage shifted more positive values. After proton irradiation, the gate leakage current increased. The Schottky barrier height changed from 0.63 eV to 0.46 eV, and the ideality factor from 2.55 to 3.98 at the highest fluence. The degradations of electrical characteristics of AlGaN/GaN HEMTs are caused by displacement damages induced by proton irradiation. The density of vacancies at different proton fluence can be calculated from SRIM. Being an acceptor-like defect, the Ga vacancy acts as a compensation center. While N vacancy acts as a donor. Adding the vacancies model into Slivaco device simulator, simulation results match well with the trends of experimental data. Hall measurement results also indicate the concentration and mobility of 2DEG decrease after proton irradiation. It is concluded that the Ga vacancies introduced maybe the primary reason for the degradation of AlGaN/GaN HEMTs performance.     

High and low-energy proton radiation damage in p/n InP MOCVD solar cells

Indium phosphide p⁺/n/n⁺ solar cells, fabricated by metal organic chemical vapor deposition, were irradiated with 0.2-MeV and 10-MeV protons to a fluence of 10¹³ cm⁻². The power output degradation, 1-V behavior, carrier concentration and defect concentration were observed at intermediate points throughout the irradiations. The 0.2-MeV proton-irradiated solar cells suffered much greater and more rapid degradation in power output than those irradiated wit h 10 MeV protons. The efficiency losses were accompanied by larger increases in the recombination currents in the 0.2-MeV proton-irradiated solar cells. The low-energy proton irradiations also had a larger impact on the series resistance of the solar cell s. Despite the radiation-induced damage, the carrier concentration in the base of the solar cells showed no reduction after 10-MeV or 0.2-MeV proton irradiations and even increased during irradiation with 0.2-MeV protons. In a deep-level transient spectro scopy study of the irradiated samples, the minority carrier defects H4 and H5 at E_v + 0.33 and E_v + 0.52 eV and the majority carrier defects E7 and E10 at E_c − 0.39 and E_c − 0.74 eV were observed. Th e defect introduction rates for the 0.2-MeV proton irradiations were about 20 times higher than for the 10-MeV proton irradiations. The defect E10, observed here after irradiation, has been shown to act as a donor in irradiated n-type InP and may be responsible for obscuring carrier removal. The results of this study are consistent with the much greater damage produced by low-energy protons whose limited range causes them to stop in the active region of the solar cell. © This article is a US Government work and, as such, is in the public domain in the United States of America     

Experimental research of heavy ion and proton induced single event effects for a Bi-CMOS technology DC/DC converter

This paper tested and analyzed heavy ion and proton induced single event effects (SEE) of a commercial DC/DC converter based on a 600 nm Bi-CMOS technology. Heavy ion induced single event transients (SET) testing has been carried out by using the Beijing HI-13 tandem accelerator at China Institute of Atomic Energy. Proton test has been carried out by using the Canadian TRIUMF proton accelerator. Both SET cross section versus linear energy transfer (LET) and proton energy has been measured. The main study conclusions are: (1) the DC/DC is both sensitive to heavy ion and proton radiations although at a pretty large feature size (600 nm), and threshold LET is about 0.06 MeV·mg/cm²; (2) heavy ion SET saturation cross section is about 5 magnitudes order larger than proton SET saturation cross section, which is consistent with the theory calculation result deduced by the RPP model and the proton nuclear reaction model; (3) on-orbit soft error rate (SER) prediction showed, on GEO orbit, proton induced SERs calculated by the heavy ion derived model are 4-5 times larger than those calculated by proton test data.     

GaN基PIN紫外探测器的质子辐照效应

摘要：制备了GaN基PIN结构紫外探测器。用能量为2MeV的质子对器件依次进行注量为5×1014cm-2和2×1015cm-2的辐照。通过测量辐照前后器件的I-V曲线和光谱响应曲线，讨论了不同注量的质子辐照对GaN基紫外探测器件性能的影响。I-V特性表明，辐照使器件的反向暗电流增大，正向开启电流减小，并减小了器件的响应率，使峰值响应波长向短波方向稍有移动。为分析器件的辐照失效机理，研究了质子辐照对GaN材料的拉曼散射谱(Raman谱)和光致发光谱(PL谱)的影响。拉曼散射谱表明，A1(LO)模式随辐照注量向低频移动，通过拟合A1(LO)谱形，得到辐照使材料的载流子浓度降低的结果。PL谱表明，辐照使主发光峰和黄光峰强度降低，并出现一些新的发光峰，分析认为这是由于辐照引起了N空位缺陷和其他一些缺陷的亚稳态造成。     

纳米器件质子在轨单粒子翻转率预计方法

研究了纳米器件在空间轨道中质子引起单粒子翻转(SEU)率的预计方法。以65 nm SRAM为样品,利用加速器进行了质子和重离子单粒子翻转试验,分别基于质子试验数据和重离子试验数据,预计了空间轨道中质子引起的单粒子翻转率。结果表明,用重离子试验数据预计的质子单粒子翻转率比用质子试验数据预计的低1.5个数量级。研究认为,为了评估纳米器件单粒子翻转敏感性,需进行质子单粒子翻转试验,并基于质子试验数据进行在轨质子翻转率预计。     

Synergistic effects of NPN transistors caused by combined proton irradiations with different energies

There are a large number of protons with different energies from the dozens of keV to hundreds of MeV in space environment, which simultaneously act on the bipolar junction transistors (BJTs), and induce different irradiation effect and damage defects. Moreover, interaction between displacement defects and ionization defects occurs. In the paper, the interaction mechanisms between oxide charge and displacement defects in 3DG112 NPN BJTs caused by the combined 70 keV and 170 keV protons with 5 MeV proton irradiation are studied. Experimental results show the degradation of current gain increases linearly with increasing the irradiation fluence of the 170 keV and 5 MeV protons, but increases nonlinearly for the 70 keV protons, implying that the 170 keV and 5 MeV protons mainly induce displacement damage on the NPN BJTs, while the 70 keV protons cause ionization damage. It can be seen from the Geant4 calculation that 70 keV and 170 keV protons cause almost the same ionization damage on the 3DG112 transistors, while have significant difference in displacement damage ability, which is favorable to analyze the effect of displacement damage in oxide layer of NPN BJTs induced by 170 keV and 70 keV protons on ionization damage caused by the subsequent 5 MeV protons. DLTS analyses show that 5 MeV protons produce mainly displacement defect centers in based-collector junction of 3DG112 transistors, and 170 keV and 70 keV protons only induce almost the same number of the oxide trapped charges. While the combined irradiation can produce the more oxide trapped charges, except displacement defects, showing that displacement damage in oxide layer caused by 170 keV and 70 keV protons can increase the oxide trapped charges during the subsequent 5 MeV exposures. Moreover, the more displacement defects in oxide layer will induce more oxide trapped charges, and give more enhanced synergistic effects. These results will help to assess the reliability of BJTs in the space radiation environment.     

强激光等离子体中质子加速的新机制

为了研究等离子体中Compton散射对靶背法向方向加速质子的影响,采用多光子非线性Compton散射模型和等离子体模拟方法,对Compton散射下等离子体中的质子加速进行了理论分析和数值模拟,提出了将入射光和Compton散射光作为在等离子体靶表面处形成的静电场加速质子的新机制,得到了质子加速的一些重要数据。结果表明,Compton散射使等离子体内产生的高能电子数增加,高能电子靶表面上所产生的静电场增强,从而使质子获得更高的加速能量;散射使静电场增强效应,有效地补偿了因激光调制不稳定性增强而造成电子在向等离子体输运过程中的能量损失,从而使质子从平缓密度标长等离子体中获得的加速能量高于从陡峭密度标长等离子体中获得的加速能量。因此,采用Compton散射下的平缓密度标长等离子体加速质子较为理想。     

总剂量辐照对65 nm NMOSFET热载流子敏感参数的影响

为了研究总剂量辐射对纳米MOS晶体管热载流子效应的影响,对65 nm 体硅工艺的NMOS器件进行了总剂量辐射和热载流子试验,对比了辐射前后不同宽长比器件的跨导、栅极泄漏电流、线性饱和电流等电参数。结果表明,MOS器件的沟道宽度越窄,热载流子效应受辐射的影响越显著,总剂量辐射后热载流子效应对器件的损伤增强。分析认为,辐射在STI中引入的陷阱电荷是导致以上现象的主要原因。该研究结果为辐射环境下器件的可靠性评估提供了依据。     

Exposure parameters for MeV proton beam writing on SU-8

Proton beam writing was performed on a lithographic resist to determine the main parameters required to achieve the minimum feature size, maximum pattern lateral density and maximum aspect ratio. A 2.5 MeV proton beam focused to sizes between 1.5 and 2.5 μm was used to expose SU-8 negative resist. The number of protons per pixel was varied in the exposure of SU-8 with thicknesses between 5 and 95 μm. Patterns consisting of single pixels, single-pixel lines and multi-pixel areas with different densities were fabricated. The smallest structures achieved were posts 1.5 μm in diameter with 4:1 structure-space ratio in 15 μm thick resist and the highest aspect ratio structures of 20:1 in 40 μm resist were produced. It was found that the minimum feature size depended only on the beam size, and ±10% post size accuracy could be achieved within 40-70% variation of the number of protons. MeV proton beam allows a direct fabrication of complex shapes without a mask in single-step irradiation and, in addition, no proximity correction is needed. We present examples of MeV proton beam written single and multi-pixel microstructures with easily reproducible high aspect ratios and densities.