光伏型长波HgCdTe红外探测器的数值模拟研究

报道了光伏型长波Hg1-xCdxTe(x=0.224)n-on-p红外探测器数值模拟研究的结果.采用二维模型,在背照射方式下,以p区厚度、两电极间距离、结区杂质浓度分布、少子寿命为参量,模拟计算了R0A积、零偏光电流与这些参量之间的变化关系.计算表明,随p区厚度增加,R0A积下降;R0A积随电极之间距离增大而增加,但量子效率随距离增大而降低,电极之间最佳距离大约为100μm;R0A积和光电流对结区杂质浓度分布形状不敏感;随少子(电子)寿命降低,R0A积和光电流下降.二维模型弥补了一维模型难以计算横向电流、电场的缺点.     

替代衬底上的碲镉汞长波器件暗电流机理

基于暗电流模型,通过变温I-V分析长波器件(截止波长为9~10μm)的暗电流机理和主导机制.实验对比了不同衬底、不同成结方式、不同掺杂异质结构与暗电流成分的相关性.结果表明,对于B+离子注入的平面结汞空位n~+-on-p结构,替代衬底上的碲镉汞(HgCdTe)器件零偏阻抗(R0)在80 K以上与碲锌镉(CdZnTe)基碲镉汞器件结阻抗性能相当.但替代衬底上的HgCdTe因结区内较高的位错,使得从80 K开始缺陷辅助隧穿电流(I_(tat))超过产生复合电流(I_(g-r)),成为暗电流的主要成分.与平面n~+-on-p器件相比,采用原位掺杂组分异质结结构(DLHJ)的p~+-on-n台面器件,因吸收层为n型,少子迁移率较低,能够有效抑制器件的扩散电流.80 K下截止波长9.6μm,中心距30μm,替代衬底上的p~+-on-n台面器件品质参数(R0A)为38Ω·cm2,零偏阻抗较n-on-p结构的CdZnTe基碲镉汞器件高约15倍.但替代衬底上的p+-on-n台面器件仍受体内缺陷影响,在60 K以下较高的Itat成为暗电流主导成分,其R0A相比CdZnTe基n~+-on-p的HgCdTe差了一个数量级.     

深亚微米MOSFET衬底电流的模拟与分析

利用器件模拟手段对深亚微米ＭＯＳＦＥＴ的衬底电流进行了研究和分析，给出了有效的道长度，栅氧厚度，源漏结深，衬底掺杂浓度以及电源电压对深亚微米ＭＯＳＦＥＴ衬底电流的影响，发现电源电压对深亚微米ＭＯＳＦＥＴ的衬底电流有着强烈的影响，热载流子效应随电源电压的降低而迅速减小，当电源电压降低到一定程度时，热载流子效应不再成为影响深亚微米ＭＯＳ电路可靠性的主要问题。     

环孔p-n结理论分析

在对环孔p-n结作近似假设的基础上，忽略了产生－复合电流、隧穿电流和表面复合电流的影响，假设在低温下扩散电流起主要作用，并认为电极与结区之间的接触为欧姆接触，建立了环孔p-n结的电流模型。根据此模型得出了环孔p-n结的电流密度方程和ROA的计算表达式，由于n区空穴的电流密度相对p区要小得多，在简化的表达式中忽略了n区电流密度的影响。最后对上述结果进行了数值分析和计算，分别做出了RoA在中波和长波波段随温度和截止波长变化曲线。从曲线可以得出：当截止波长在中波波段3－5μm时，77－150K的温度范围都可以使用，但只有在130K或更低的温度下才有较好的性能。目前在中波段的R0A值已经达到10^9Ωcm^2，比理论值要低2－3个数量级；对于8－10．4μm波段，120K以下都有性能，而10－14μm波段，要工作在100K温度之下。     

场效应管使用原则

以N沟道为例，它是在P型硅衬底上制成两个高掺杂浓度的源扩散区N＋和漏扩散区N＋，再分别引出源极S和漏极D。源极与衬底在内部连通，二者总保持等电位。当漏接电源正极，源极接电源负极井使VGS=0时，沟道电流（即漏极电流）ID=0。随着VGs逐渐升高，受栅极正电压的吸引，在两个扩散区之间就感应出带负电的少数载流子，[第一段]     

一种测定p型HgCdTe中空穴浓度的常规方法

近年来用CMT制作光电二极管的兴趣有所增长。CMT光电二极管可供电子扫描混合焦平面列阵使用。目前大多数器件是使用一块带n型表面的少型薄片制造的,该n型表面层是通过离子注入或扩散当中任何一种方法产生的。在两种类型的结中,R_0A乘积依赖于p型衬底的净掺杂浓度。例如在离子注入结中,如果衬底的掺杂浓度太高,即使在零偏压下,结的隧道电流也可限制其性能。要获得具有高零偏压的结面电阻—R_0A之积[1]—的离子注入探测器,就必须将载流子浓度确定为1×10~(16)cm~(-3)或者更小一些。     

HA—8502电话机故障检修

故障现象拨号误码多，其他功能基本正常。分析检修测量集成电路A2的工作电压正常。由图1可知，A2的工作频率主要取决于R25和C14，若图1工作频率相关电路它们老化变值，则使A2工作频率偏离正常值，脉冲发送速度不符合标准，结果导致电话交换机不能准确接收电话机发送的脉冲个数。焊开R25、C14，检查发现C14和R25均老化。更换R25和C14，故障排除。故障现象拨号时错时对，其他功能良好。分析检修检查集成电路A2的工作电压和工作频率正常。如图2如示，脉冲发送电路的V4和V5因使用年久老化和β值下降造成饱和、截止深度不够，使话机发出的…     

三视频D／A变换器接口电路

Fairchild半导体公司的TMC3033是一款高速三视频10位D／A变换器,特别适合于视频和图像应用。它提供10位分辨率、TTL兼容输入、低功耗,只需一个+3．3V电源。它具有单端电流输出、SYNC（同步脉冲）和BLANK（消隐）控制输入以及一个用以把同步脉冲添加到GreenD／A变换器输出的独立电流源。对于从数字RGB产生模拟RGB和驱动计算机显示及视频监视器,TMC3033是理想的器件。它有三个速度等级：30、50和80Msps。三视频D／A变换器TMC3033的典型接口电路示于图1。其中R9-0为红色象素输入,G9-0为绿色象素输入,B9-0为蓝色象素输入,…     

InAs/GaSb 超晶格中波红外二极管的IV 特性研究

采用分子束外延（MBE）技术,在GaSb 衬底上生长了pin 结构的InAs（8ML）/GaSb（8ML）超晶格中波红外光电二极管。经过（NH4）2S 表面钝化后的IV 特性曲线表明:低的正偏压下,理想因子n 在 2 左右,势垒区的复合电流起主要作用;偏压超过0.14 V 时,n 在1 左右,少子扩散电流占主。表面势垒区中过多的III 族元素的空位缺陷导致表面出现大量复合中心。采用阳极硫化后,表面漏电大大减小,反偏漏电流密度降低三个数量级,零偏阻抗R0 达到106 欧姆,R0A 达到103 量级。     

直接带间隧道对长波Hg_(1-x)Cd_xTePN结的影响

基于Kane隧道电流模型并考虑费密-狄拉克分布函数的影响,导出了直接带间隧道电流及相应的零偏压电阻-面积乘积R_0A的表达式。对Hg_0.8CD_0.2TePN结的计算结果表明,直接带间隧道是限制结特性的一种重要的电流机构。分析了这种电流机构对Hg_0.8CD_0.2TePN结伏-安特性及R_0A的影响,以及它们与PN结两侧掺杂浓度和工作温度的依赖关系。对N~+P和P~+N这两种结构的器件进行了比较。为了计算隧道电流,对结两侧的准费密能级也作了计算。     

不锈钢基底高电流密度YBCO超导线材

室温下应用Ａｒ＋ 离子源辅助准分子脉冲激光沉积（００２）取向的ＹＳＺ（Ｙｔｔｒｉａ－ｓｔａｂｉｌｉｚｅｄ ｚｉｒｃｏ－ｎｉａ）过渡层薄膜于不锈钢基底上;基底加温至７５０℃,用准分子脉冲激光沉积高电流密度ＹＢＣＯ（ＹＢａ２Ｃｕ３Ｏ７－ ｘ） 高温超导线材。实验结果表明：ＹＢＣＯ 超导线材临界温度Ｔｃ ≥９０ Ｋ （Ｒ＝０）,临界电流密度Ｊｃ ≥１×１０６ Ａ／ｃｍ ２（７７ Ｋ,０ Ｔ）。     

Second substrate current peak and its relationship to gate-voltage dependent series resistance in submicrometre nMOS LDD transistors

The occurrence of the second substrate current hump (SSCH) has been thoroughly investigated and it is well known that the lateral electric field at the source side (E/sub s/) is responsible for the appearance of the SSCH in submicrometre nMOS LDD transistors. However the fall off of the SSCH after reaching a maximum value, the so called second substrate current peak (SSCP), is not well understood and explained. Here an improved model of the lateral electric field at the source side, which explains the SSCP in terms of the dependence of the source series resistance R/sub is/ on the gate-source voltage, is introduced.<>     

Two-dimensional numerical simulation of side-gating effect in GaAsMESFETs

Two-dimensional device simulations that confirm that the side-gating effect in GaAs MESFETs occurs on semi-insulating substrates containing hole traps are discussed. A negative voltage applied on a side gate, a separate n-type doped region, causes an increase in the thickness of the negatively charged layer at the FET channel interface in the substrate, through hole emission from hole traps. The FET channel current is modulated by the electron depletion of the n-type channel, which results from the compensation for the extension of the negatively charged layer at the n-i interface into the i-substrate containing hole traps. The magnitude of the drain current reduction is determined by the total acceptor concentration in the substrate and the donor concentration of the channel. However, the magnitude is independent of the side-gate distances     

气态源分子束外延生长扩展波长InGaAs探测器性能分析

从理论与实验两方面对截止波长为1.7μm(x=0.53),1.9μm(x=0.6)和2.2μm(x=0.7)p in InxGa1-xAs探测器性能进行了研究.对探测器暗电流的研究结果表明,扩展波长In0.6Ga0.4As,In0.7Ga0.3As探测器在反向偏置低压区,欧姆电流占据主导地位;在反向偏置高压区,缺陷隧穿电流占主导地位;且扩展波长In0.6Ga0.4As,In0.7Ga0.3As探测器的暗电流比In0.53Ga0.47As探测器增加较大.对探测器R0A随温度及i层载流子浓度变化关系的研究结果表明,在热电制冷温度下探测器性能可得到较大提高,i层的轻掺杂可使探测器的R0A得到改善.     

Measurement of the minority-carrier transport parameters in heavily doped silicon

A new method for simultaneous measurement of bandgap narrowing and diffusion length in a heavily doped n⁺substrate is proposed. The method uses planar test pattern at the front side of the substrate to determine the hole minority-carrier current injected from a p-type emitter and diodes at the rear side to measure diffusion lengths. The method can be generalized such that the minority-carrier diffusion constant can be estimated and the use of extrapolated literature data can be avoided. Results of measured values of bandgap narrowing and diffusion length versus impurity concentration are given for n-type material.     

Electromigration Failure Mechanism in Sn-Cu Solder Alloys with OSP Cu Surface Finish

Organic solderable preservative (OSP) has been adopted as the Cu substrate surface finish in flip-chip solder joints for many years. In this study, the electromigration behavior of lead-free Sn-Cu solder alloys with thin-film under bump metallization and OSP surface finish was investigated. The results showed that severe damage occurred on the substrate side (cathode side), whereas the damage on the chip side (cathode side) was not severe. The damage on the substrate side included void formation, copper dissolution, and formation of intermetallic compounds (IMCs). The OSP Cu interface on the substrate side became the weakest point in the solder joint even when thin-film metallization was used on the chip side. Three-dimensional simulations were employed to investigate the current density distribution in the area between the OSP Cu surface finish and the solder. The results indicated that the current density was higher along the periphery of the bonding area between the solder and the Cu pad, consistent with the area of IMC and void formation in our experimental results.     

Characteristics of GaAs lasers near room temperature

The efficiency and threshold of GaAs lasers can be affected by a delay occurring between the application of a current pulse and the laser output. The delays may be some tenths of a microsecond in certain diffused junction lasers when operated near room temperature, e.g., when the donor substrate dopant is selenium with a concentration of the order of 10¹⁸atoms per cm³. No such delays are observed in diodes in which the substrate dopant is silicon. In the case of selenium, the delay depends on the doping level, decreasing as the concentration increases. The delay is also very sensitive to injection current, decreasing rapidly with increasing current from its maximum at threshold. During the pulse, after lasing commences, the output continues to increase. A similar effect has also been observed with spontaneous emission. Operation of these devices below room temperature shows that the delay is also dependent on temperature. The delay decreases over a fairly narrow temperature range and in all cases is no longer observed ( < 20 n/s) below -70°C. These observations are explained by considering the effect of impurity trapping levels which may be associated with the     

0.18μm工艺下p-n结电荷收集的三维TCAD模拟

采用三维TCAD模拟的手段,针对0.18μm工艺下的真实p-n结,研究了偏雎、温度、衬底掺杂浓度和LET对辐射诱导的SET电流脉冲的影响.研究结果表明,在1.62～1.98V的范围内,偏压对电流脉冲的形状有明显影响,而对2ns内的电荷收集总量几乎没有影响;电流脉冲峰值和2ns内的电荷收集总量均随着温度的增加而降低,但温度对电流脉冲峰值的影响更大,而对电荷收集总量的影响相对较小;在典型的现代工艺条件下,衬底掺杂浓度的起伏对单粒子加固性能的影响基本可以忽略;电流脉冲的峰值和电荷收集量二者均随着LET的增加而增加.     

Characteristics of gradually doped LWIR diodes by hydrogenation

The hydrogenation effects on HgCdTe diode performance are presented and the mechanism of hydrogenation is revealed. By the hydrogenation, R₀A is increased by 30 times and photo-response is also improved. It is supposed that these are explained by the increased minority carrier lifetime by the hydrogenation. However, it is found from LBIC measurements that the minority carrier lifetime doesn’t increase by the hydrogenation. An important clue that explains the hydrogenation effects is found from Hall measurements. It is found that, after the hydrogenation, the doping concentration of Hg-vacancy doped substrate decreases and the mobility increases. For the heavily hydrogenated bulk substrate, it is also found that the hydrogen passivates the whole Hg-vacancy and reveals the residual impurity and p-type doping concentration is exponentially graded. From these measurements, the diffusion current model of gradually doped diode is proposed. This model shows that the diffusion current of the graded junction diode is 2 orders of magnitude smaller than that of the abrupt junction diode, which clearly explains the R₀A increase by the hydrogenation. Medicisimulation to investigate the change of LBIC signal by the doping grading also coincides with the measurements. From these measurements and model, the hydrogenation effects are attributed to the grading of Hg-vacancy doped p-type substrate by the diffused hydrogen.     

基于LCP柔性衬底的MEMS V型梁结构的设计制备与表征

为探索在复杂环境应用中柔性衬底弯曲对V型梁结构力学特性的影响,提出了一种基于LCP柔性衬底弯曲条件下MEMS V型梁结构的力学分析方法,对柔性MEMS V型梁器件的弯曲特性从软件仿真和实验验证两个方面进行深入的研究。揭示了MEMS V型梁衬底发生弯曲后,对器件驱动性能的影响。实验结果表明,当柔性衬底弯曲曲率从0增大到33.3 m^-1,V型梁热驱动器的驱动电流逐渐增大,测量值与仿真值的误差小于6.0%,与理论模型相符。