Pulse and frequency response of a p-i-n photodiode with absorption layer fabricated in two-valley semiconductor

Starting from the transport equations of the phenomenological model for a two-valley semiconductor, we obtained the pulse response of a p-i-n photodiode with the absorption layer fabricated in a two-valley semiconductor (GaAs, InGaAs...). The pulse response was determined for the case when it was possible to linearize the transport equations. It was shown that the nonstationary effects influence significantly the intensity and speed of the response. The frequency response was obtained by applying the fast Fourier transform (FFT) to the pulse response.     

Bias-dependent timing jitter of 1-GHz sinusoidally gated InGaAs/InP avalanche photodiode

We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage(V_(ex)) when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V_(ex) is too low(0.2 V-0.8 V) or too high(3 V-4.2 V),the timing jitter is increased with the V_(ex),particularly at high V_(ex).While at middle V_(ex)(1 V-2.8 V),the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V_(ex) and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of ~2.08×10~(-5) per gate at the V_(ex) of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power(NEP) and the afterpulse probability(P_(ap)).It is found that both NEP and P_(ap) increase quickly when the V_(ex) is above 2.8 V.At ~2.8-V V_(ex),the NEP and P_(ap) are ~2.06×10~(16)W/Hz~(1/2) and 7.11%,respectively.Therefore,the detector should be operated with V_(ex) of 2.8 V to exploit the fast time response,low NEP and low P_(ap).     

Far-infrared electroluminescence characteristics of an Si-based photodiode under a forward DC bias current

At room temperature,the bias dependence of a far-infrared electroluminescence image of a photodiode is investigated in the dark condition.The results show that the electroluminescence image can be used to detect defects in the photodiode.Additionally,it is found that the electroluminescence intensity has a power law dependence on the dc bias current.The photodiode ideality factor could be obtained by a fitting a relationship between the electroluminescence intensity and the bias current.The device defect levels will be easily determined according to the infrared image and the extracted ideality factor value.This work is of guiding significance for current solar cell testing and research.     

偏压对空心阴极放电等离子体溅射制备氮化碳薄膜的影响

利用空心阴极放电等离子体源在Si（100）单晶衬底上沉积了氮化碳薄膜．薄膜的表面形貌表明所得的薄膜非常的均匀光滑，用X光电子能谱、拉曼和红外吸收光谱对薄膜的结构、成分和化学键等进行了研究．在拉曼光谱中可以看到典型的G，D和C=N键的峰．当偏压为250V时．薄膜拉曼光谱中的D峰完全消失，此时薄膜的N／C比达到了0．81．通过对薄膜的XPS分析也表明薄膜中C—C，sp^2 CN和sp^3 CN键的组分也发生了明显的变化．当偏压为250V时薄膜的sp^3 CN相的含量达到了最大值为40％，同时氮含量也达到了最大值．实验结果给出了直接的证据：薄膜的结构模式可以通过改变偏压来得到控制．     

毫秒脉冲激光致硅光电二极管电学损伤的有限元分析及实验研究

为了研究毫秒脉冲激光致硅基PIN光电二极管电学损伤,基于热传导及弹塑性力学理论,在光电二极管内部材料各向同性并且P-I-N三层结构之间满足温度连续和热流平衡条件下,建立毫秒脉冲激光辐照硅基PIN光电二极管二维轴对称模型,采用有限元方法模拟分析了1064 nm Nd:YAG毫秒量级脉冲激光辐照硅基PIN光电二极管的温度场与应力场分布,并实验测量了硅基PIN光电二极管实验前后的电学参数.结果表明,激光辐照硅基PIN光电二极管时,温升使材料表面熔融、烧蚀,并且在空间上存在温度梯度变化,即激光辐照产生的热与应力使光敏面及硅晶格晶键损伤,最终造成光电探测器的探测性能下降.研究结果可为毫秒脉冲激光辐照硅基PIN光电二极管电学损伤机理奠定基础.     

瞬态抑制二极管电磁脉冲响应建模

针对目前浪涌保护器件性能分析方法不完善、缺乏准确数学模型的问题,提出了一种基于NARX神经网络的电磁脉冲响应时域建模方法,并给出NARX神经网络建模的理论基础及设计步骤。通过组建传输线脉冲测试平台及静电放电实验平台,对NUP2105L型瞬态抑制二极管进行注入实验,采集输入输出实验数据并建立NARX神经网络模型。对建模效果进行分析,所建模型可以较为准确地预测输入脉冲为方波脉冲、人体金属模型及机器模型静电放电电磁脉冲时,响应电压曲线趋势、响应时间、脉冲峰值、箝位时间及箝位电压等性能指标,验证了模型的正确性。     

亚纳秒脉冲高电压测量探头

为测量紧凑型快前沿高电压脉冲源的输出电压,设计了D-dot电压探头。分别进行了刻度因素标定和频响标定,采用前沿约50 ns的高压脉冲信号对探头进行在线标定确定探头的刻度因素。将探头安装在阻抗为50 的传输线上,用亚纳秒脉冲源进行频响标定,表明该探头的响应约为150 ps。高压实验结果表明该探头能够正确获取高电压快脉冲信号,工作稳定可靠。     

Non-depletion floating layer in SOI LDMOS for enhancing breakdown voltage and eliminating back-gate bias effect

A non-depletion floating layer silicon-on-insulator (NFL SOI) lateral double-diffused metal-oxide-semiconductor (LDMOS) is proposed and the NFL-assisted modulated field (NFLAMF) principle is investigated in this paper. Based on this principle, the floating layer can pin the potential for modulating bulk field. In particular, the accumulated high concentration of holes at the bottom of the NFL can efficiently shield the electric field of the SOI layer and enhance the dielectric field in the buried oxide layer (BOX). At variation of back-gate bias, the shielding charges of NFL can also eliminate back-gate effects. The simulated results indicate that the breakdown voltage (BV) is increased from 315 V to 558 V compared to the conventional reduced surface field (RESURF) SOI (CSOI) LDMOS, yielding a 77% improvement. Furthermore, due to the field shielding effect of the NFL, the device can maintain the same breakdown voltage of 558 V with a thinner BOX to resolve the thermal problem in an SOI device.     

感应电压叠加器模块对方波脉冲的响应

为了解感应电压叠加器(IVA)对馈入脉冲的响应特性,尤其对上升前沿、平顶的影响,从理论和实验两个方面对IVA模块进行了研究。介绍了IVA的工作原理,利用集总参数方法建立了相应的电路模型,通过拉普拉斯变换分析了感应电压叠加器对方波脉冲上升前沿和平顶的响应,并在一个特定的IVA模块上进行了实验研究。选择输出阻抗约1.2Ω、脉宽约1μs的脉冲形成网络作为馈源,在匹配负载上得到的波形与输入波形在幅值、上升前沿方面达到了很好的吻合,平顶出现略微的顶降,与理论预期相一致。     

铁基非晶磁环的高频响应和ns级脉冲响应特性

为了获取高频和快脉冲条件下铁基非晶磁芯的重要特性参数,对三种国产铁基非晶磁环的高频响应和快脉冲响应特性进行了实验研究.通过1∶1变压器测试回路发现,在1～20 MHz等振幅正弦源信号作用下,磁芯响应信号幅度损失率从0陡增至50％～60％,当源信号频率继续增大时,响应信号幅度损失率维持在50％～60％.对磁芯快前沿脉冲响...     

The effect of applied negative bias voltage on the structure of Ti-doped a-C:H films deposited by FCVA

Ti-doped hydrogenated diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates by a filtered cathodic vacuum arc (FCVA) method using Ar and CH₄ as the feedstock. The composition and microstructure of the films were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy and IR spectroscopy. The internal stress was determined by the radius of curvature technique. The influence of the bias voltage on the microstructure of the as-deposited films was investigated. It was found that the graphite-like bonds was dominated in the Ti-doped DLC film deposited at 0 V bias voltage. When bias voltage was increased to −150 V, more diamond-like bond were produced and the sp³ content in film reached the maximum value, after which it decreased and more graphite-like bonds feature produced with further increase of the negative bias voltage. The compressive internal in the Ti-doped DLC films also exhibited a maximum value at −150 V bias voltage. IR results indicated that CH bonded intensity reduced, and H atoms bonded with C atoms were substituted for the Ti atoms as the negative bias voltage increasing. All the composition and microstructure change can be explained by considering the plasma conditions and the effect of negative bias voltage applied to the substrate.     

铁基非晶磁环的高频响应和ns级脉冲响应特性

为了获取高频和快脉冲条件下铁基非晶磁芯的重要特性参数,对三种国产铁基非晶磁环的高频响应和快脉冲响应特性进行了实验研究。通过1∶1变压器测试回路发现,在1~20 MHz等振幅正弦源信号作用下,磁芯响应信号幅度损失率从0陡增至50%~60%,当源信号频率继续增大时,响应信号幅度损失率维持在50%~60%。对磁芯快前沿脉冲响应特性进行频谱分析和实验研究的结果表明：受高频涡流损耗影响,磁芯对脉宽小于30 ns时的方波信号的幅度和平顶响应较差;源信号脉宽大于100 ns时,响应信号基本可与源信号重合,且最短前沿响应时间为10 ns。给出了20 Hz~1 MHz周期信号作用下,磁芯相对磁导率随频率的变化曲线。最后给出了在ns级快前沿脉冲作用下,磁芯脉冲磁导率的估算方法和测量结果。     

感应电压叠加器模块对方波脉冲的响应

为了解感应电压叠加器（IVA）对馈入脉冲的响应特性,尤其对上升前沿、平顶的影响,从理论和实验两个方面对IVA模块进行了研究。介绍了IVA的工作原理,利用集总参数方法建立了相应的电路模型,通过拉普拉斯变换分析了感应电压叠加器对方波脉冲上升前沿和平顶的响应,并在一个特定的IVA模块上进行了实验研究。选择输出阻抗约1.2 Ω、脉宽约1 μs的脉冲形成网络作为馈源,在匹配负载上得到的波形与输入波形在幅值、上升前沿方面达到了很好的吻合,平顶出现略微的顶降,与理论预期相一致。     

离子束辅助工艺中APS源偏转电压对HfO2薄膜性能的影响

基于Leybold APS1104镀膜系统,采用离子束辅助反应沉积技术,以金属Hf粒为初始镀膜材料,APS源偏转电压为50~140 V范围内,在［100］单晶硅片和紫外石英（JGS1）基板上制备了HfO2单层膜。分别利用Lambda 900分光光度计、X射线光电子能谱仪、X射线衍射仪以及原子力显微镜对HfO2薄膜的光谱性能、表面及纵向化学成分、晶相结构以及表面粗糙度进行了分析。结果表明：当APS源偏转电压在120~140 V及50~90 V两个范围内变化时,HfO2薄膜的紫外短波光学损耗随着偏转电压的降低而减小,而为110~90 V时紫外短波光学损耗对偏转电压的变化不敏感;偏转电压在50~140 V的范围内时,制备的HfO2薄膜表面及纵向化学成分无明显变化;当偏转电压为100 V时,HfO2薄膜晶粒尺寸及表面粗糙度分别达到最大值26.2 nm及5.79 nm,其后,随着偏转电压的降低,二者均逐渐减小。     

纳秒脉冲电压下气体开关的击穿特性

 采用快速Marx发生器产生ns量级的高电压脉冲,分别开展了不同脉冲电压值下气体开关自击穿实验,获得了气体开关在不同气压下的击穿电压和击穿延迟时间以及抖动。详细介绍了纳秒脉冲电压作用下,气体火花开关击穿电压和击穿延迟时间随工作气压变化的特点,指出了气体开关在不同场合应用时的要求。     

用光电二极管列阵测干涉条纹周期的精度分析

分析了用1024单元的光电二极管列阵测量干涉条纹周期时,采样密度对测量精度的影响.采样数据的量化为256,每个干涉条纹的采样点数从10至30左右时,测量精度最高,可优于2×10~(-5).量化小时,最佳采样密度变小.     

激光电致发光薄膜屏的高压脉冲电源

这种脉冲电源的设计不同于市售的脉冲电源，它具有电路结构简单，体积小，电压高，正负脉冲叠加，具有快的上升时间，稳定性能好等特点。最适合于做为电致发光屏和电致发光薄膜屏的激发源。是测量发光屏的强度、寿命、时间分辨光谱的非常适用的激发源。     

负非线性夹层式光开关原理

根据光致热效应讨论了负非线性夹层式光开关的时间响应特性。利用热传导方程和两个热力学方程，在绝热假设下分析了影响其全反射响应时间的因素，应用这一理论模式对Ｓｔｒｏｂｌ提出的样品材料进行了计算，理论与实验结果相吻合。     

Responsivity analysis of micro-bolometer under pulsed bias

The physical thermal model for micro-bolometer under pulsed voltage bias is built, and the current responsivity expression of the micro-bolometer based on this physical thermal model is approximatively obtained in theory, which is in accordance with the numerical calculation of micro-bolometer current responsivity. Theoretical analysis shows that the current responsivity parameter is changed with voltage bias time, and this indicates that the current responsivity of micro-bolometer under pulsed voltage bias can be controlled by adjusting useful voltage bias time which is equal to micro-bolometer current integration time. The expression of the current responsivity parameter reveals key factors relevant to the output signal signal-to-noise of micro-bolometric focal plane array, and theoretically gives one of the directions to increase the output signal signal-to-noise of micro-bolometric focal plane array.