单粒子效应激光模拟试验技术研究

介绍了一种新的单粒子效应模拟试验技术——脉冲激光模拟试验方法。对脉冲激光束进行单粒子效应试验研究的基本机理进行了分析讨论。总结分析了电子器件及集成电路单粒子效应激光模拟试验研究结果,给出了单粒子效应脉冲激光模拟试验的一般评估方法,并对采用脉冲激光模拟单粒子翻转试验获得的试验数据与重离子试验数据的等效性进行了比对分析。结果表明,激光模拟试验得出的LET阈值大小与重离子试验结果基本一致。     

器件表面钝化层对脉冲激光等效重离子LET值的影响

介绍了激光模拟单粒子效应实验中,脉冲激光能量等效重离子线性能量传输(LET)值的理论计算方法,分析了器件表面钝化层对脉冲激光能量和重离子LET等效性计算的影响。受SiO2钝化层的调制,进入Si衬底的脉冲激光能量只占入射到器件表面激光能量的21.6%～16.1%。如果器件表面的钝化层厚度已知,且不考虑非线性效应,就可以利用激光强度透射率函数,算出更精确的脉冲激光能量等效重离子LET值。理论计算结果与相关文献报道的重离子LET值非常接近。     

图像传感器单粒子效应脉冲激光实验研究

针对设计研制的512×512 CMOS APS图像传感器,采用聚焦脉冲激光束研究了其空间单粒子效应特性。试验结果表明,CMOS APS器件图像传感器存在单粒子翻转（SEU）和单粒子锁定（SEL）现象。验证了CMOS APS图像传感器抗单粒子锁定设计的有效性。当对图像传感器移位寄存器区进行照射时,同时发生单粒子翻转和单粒子锁定,器件其它区域也有类似现象。分析了器件单粒子效应的敏感性,获得了器件发生单粒子翻转和锁定的脉冲激光能量阈值及器件锁定电流大小。     

脉冲激光参数在烧蚀固体材料过程中的影响

介绍长脉冲激光和短脉冲激光与固体材料相互作用时的物理模型。介绍激光作用过程中,脉宽、波长等激光参数对材料烧蚀阈值以及加工质量的影响。     

纳秒激光辐照对类金刚石薄膜的损伤及改性

利用Nd:YAG纳秒激光(波长分别为355、532和1 064 nm)辐照由电子束蒸发技术制备的类金刚石(DLC)薄膜,通过光学显微镜、光学轮廓仪和拉曼光谱仪等分析了辐照后的薄膜样品,结果表明:不同波长的单脉冲激光辐照时,DLC膜的激光损伤阈值不同;同一波长的多脉冲激光辐照时,损伤阈值低于单脉冲辐照阈值;脉冲激光辐照对DLC膜具有改性作用,受辐照薄膜区域表层发生了石墨化、剥落和气化效应,致使DLC膜表面出现了隆起和弹坑,隆起高度和弹坑深度与激光能量密度大小和脉冲个数有关.     

单粒子效应的激光模拟方法研究进展

单粒子效应是一种会引起器件状态改变的辐射效应现象,会对器件性能、状态造成重大影响,甚至可能造成器件无法正常工作.本文介绍了目前各种单粒子效应的研究方法,重点综述了脉冲激光模拟研究的进展,汇总了近些年来国内外的代表性研究机构以及相应的测试装置参数,同时对脉冲激光诱导产生单粒子效应的机理、研究测试方法和代表性前沿器件研究的成果进行了概括,最后对脉冲激光模拟单粒子效应的方法、器件的研究方向等进行展望.     

CMOS APS光电器件单粒子效应脉冲激光模拟实验研究

CMOS APS光电器件因低功耗、小体积的特点已成为遥感卫星成像的重要发展方向。随着半导体技术的不断进步,其单粒子效应已经成为一个影响可靠性的重要因素。针对CMOS APS光电器件,利用实验室脉冲激光模拟单粒子效应设备模拟了重离子在APS光电器件中引起的辐射损伤,分析了CMOS APS光电器件内部不同功能单元对单粒子效应的敏感性,获得了单粒子效应敏感参数。结果表明,CMOS APS光电器件在空间辐射环境中会诱发单粒子翻转和单粒子锁定。研究结果为进一步分析CMOS APS光电器件的抗辐射加固设计提供了理论支持。     

ns脉冲激光诱导制备铬掺杂ZnSe纳米粒子独特的生长以及光学特性

在液相环境中,利用纳秒（ns）脉冲激光器轰击消融铬掺杂ZnSe（Cr^2＋：ZnSe）微米颗粒,制备出Cr^2＋：ZnSe纳米粒子,扫描电镜以及X射线衍射检测,结果显示,制备所得的粒子为平均尺寸为50nm的ZnSe闪锌矿结构纳米粒子。基于Cr^2＋：ZnSe纳米粒子,观察到中心波长为2180nm、阈值为0．4mJ／pulse的随机激光效应。相比于Cr^2＋：ZnSe晶体激光器,纳米粒子随机激光的中心波长发生了约170nm的蓝移,Cr^2＋：ZnSe纳米粒子的光致发光寿命也比Cr^2＋：ZnSe晶体要短。     

飞秒激光与金膜作用的脉冲累积效应

采用1kHz飞秒激光（脉宽148fs，中心波长775nm）对石英衬底的金膜的烧蚀过程进行了研究．单脉冲与多脉冲的烧蚀阈值可以通过烧蚀点的直径平方与所用的激光能流的关系曲线获得．通过累积能流和烧蚀脉冲数的关系，可以得到金膜的脉冲累积因子．采用飞秒激光加工材料的一些特点可以合理解释单脉冲阈值附近获得的一些实验现象．     

单粒子光散射脉冲信号幅度分布的分形特征

借助于激光尘埃粒子计数光电传感器,对单粒子产生的随机散射光脉冲信号的幅度分布特征进行统计测量,发现不同粒径标准粒子、空气中的尘埃粒子以及光电传感器随机噪声等对应的脉冲信号数随幅度的分布具有对数正态分布形式.随机脉冲信号数随幅度分布规律是随机过程统计特性的表现,并可证明,对数正态分布函数具有广义分形的基本特征.     

CO2 laser radiation confinement in a composite material containing silver nanoparticles

Experimental data are reported on the optical confinement of a pulsed 10.6 μm laser radiation in a composite comprising a dielectric medium with linear optical properties containing dispersed silver nanoparticles. The energy threshold for the laser radiation confinement at a pulse duration of 2 μs does not exceed 10μ J/cm²     

Intracavity pumped nanosecond optical parametric oscillator emitting in the eye-safe range

We report on a 1.57-mum wavelength singly resonant optical parametric oscillator (OPO) using a noncritically phase-matched KTP crystal intracavity pumped by an electro-optically Q-switched Nd:YAG laser. A simple model for numerical calculation of the temporal profile of the laser and signal pulses developed inside the intracavity pumped OPO (IPOPO) resonator is described. Working conditions for single-pulse and multipulse parametric oscillation are established. A single signal pulse of 8.1-mJ output energy was obtained when the laser was pumped three times above the pulsed IPOPO threshold. A pulse duration of 5.9 ns was measured at 1.5 times above threshold for the IPOPO.     

Special features of the periodic-pulse-train laser radiation confinement in doped gallium arsenide and zinc selenide

Experimental data on the pulsed laser radiation confinement in compensated GaAs and ZnSe with deep impurity levels are reported for the laser wavelength λ=1.55 μm and a pulse repetition frequency of up to 100 kHz. It is demonstrated that an increase in the pulse repetition rate is accompanied by a decrease in the energy confinement threshold and by an increase in the radiation attenuation coefficient. These effects are explained by the accumulation of nonequilibrium charge carriers related to a dependence of the recombination time constant on the concentration of free impurity centers.     

Modelling and mitigation of single-event upset in CMOS voltage-controlled oscillator

Single-event effects (SEEs) have been the primary concern in study of radiation effects since late 1970s with the discovery of soft errors in terrestrial and space environments. The interaction of a single ionized particle with electronic devices leads to SEEs. In this paper, single-event upset (SEU) on CMOS devices in designing of a voltage-controlled oscillator (VCO) is analysed. Further, mitigation approaches of SEU are also discussed. To observe the impact of radiation, a VCO was designed in Cadence Virtuoso, and GDSII file of one ring oscillator stage was extracted to incorporate the same design in Silvaco MaskViews. With the help of layer map information file, masks were identified and used to design the CMOS inverter structure file for simulation of SEU condition. The input parameters for SEU simulation were evaluated from linear energy transfer (LET) graph of heavy ion under space conditions. The current profile of CMOS inverter was extracted under influence of a high-energy particle with the help of LET graph of that particle. This current profile was applied to different nodes of VCO and upset conditions were identified. Further, the impact of upset conditions on lock stage of phase-locked loop (PLL) is discussed. Results show that the SEU has significant impact on the logic state of inverters used in ring oscillator stage compared with current starving/biasing stage. The current profile of CMOS device has strong dependence on the energy of ion, its track, angle of incidence and the material. When angle of incidence is very less (\(7^{\circ }-14^{\circ }\)) the channel will be occupied by a funnel of charge and it leads to the maximum degradation of device. This work shows that a device operating at high frequency is more susceptible to SEU. Triple modular redundancy (TMR) and Radiation Hardened By Design (RHBD) can be used to mitigate SEU. TMR consumes more power and is less accurate compared with the RHBD approach.     

Optical confinement of a laser radiation in the 3.8–4.2 μm range in a composite material containing silver nanoparticles

The results of experiments on the nonlinear optical confinement of a pulsed 3.8–4.2 μm laser radiation in a composite comprising a silver-halide-based dielectric matrix containing dispersed silver nanoparticles are presented. It is shown that, for a laser pulse duration of 250 ns, the energy threshold for the laser radiation confinement is 5 mJ/cm² and the dynamic confinement range exceeds 10.     

Preparation of AlSb films by laser annealing

The preparation of AlSb thin films by the pulsed laser annealing of Al/Sb sandwiches was studied in order to resolve some past controversy about the temperature rise induced by the laser pulse. Using films 1000 Å thick supported by transmission electron microscope grids, we investigated the energy threshold for complete transformation into AlSb as a function of pulse duration from 35 ns to 100 ms and at film temperatures ranging from -100 to 350 °C. By extrapolation we obtained the temperature rise directly induced by the laser beam as about 650 °C, i.e. approximately the melting point of the two metals, whereas during anneals of comparable films in an inert gas furnace the transformation at this temperature only occurs in times exceeding 100 s. We discuss the isoenergetic nature of the system for short laser pulses and the role of the heat of transformation, and we conclude that the reaction is thermally triggered by the laser pulse but is to some extent self-sustained via the heat of transformation which is locally distributed. Further, the laser-induced crystal growth is shown to be influenced by the beam shape.     

Energy Transfer Modes in Pulsed Laser Seam Welding

A systematic parametric study has been made in pulsed Nd:YAG laser welding to understand the energy transfer modes. Four different energy transfer zones, namely conduction, transition, penetration, and keyhole, have been identified. The traditional classification of energy transfer modes based on the power density value of 10⁶ W/cm² is not strictly applicable as the transfer mode varies with pulse duration. The threshold power density to form keyhole is not constant, but the threshold energy density has been found to be invariant around 2.4 kJ/cm². The pulse duration has been optimized to be of about 8 ms to achieve welds of higher aspect ratio.     

Green lasers based on CdSe/ZnSe nanostructures pumped by electron beams with energies below 10 keV

We have studied the output characteristics of pulsed electron-beam-pumped green lasers based on ZnSe-containing quantum-sized structures with thin (20 nm thick) external ZnMgSSe confinement layers. Room-temperature lasing has been observed for electron beam energies above 3.7 keV. At a beam energy of 8–9 keV, the minimum threshold beam current density was 0.4–0.5 A/cm². The maximum laser output pulse energy was 2 W at a pumping electron beam energy of ～5 kW.