Influence of the external component on the damage of the bipolar transistor induced by the electromagnetic pulse

A study on the influence of the external resistor and the external voltage source during the injection of the electromagnetic pulse(EMP) into the bipolar transistor(BJT) is carried out.Research shows that the increase of the external resistor R_b at base makes the burnout time of the device decrease slightly,the increase of the external voltage source V_(be) at base can aid the damage of the device when the magnitude of the injecting voltage is relatively low and has little influence when the magnitude i...     

一种高单位增益带宽CMOS全差分运算放大器

设计并讨论了一种高单位增益带宽CMOS全差分运算放大器。由于折叠共源共栅结构电路具有相对高的单位增益带宽以及开关电容共模反馈电路稳定性好、对运放频率特性影响小等优点,故设计的放大器采用了折叠共源共栅结构以及开关电容共模反馈电路技术,并达到了高单位增益带宽的设计目的。基于TSMC0·25μmCMOS工艺,仿真结果表明,在2·5V的单电源电压下,运算放大器的直流开环增益为70dB,单位增益带宽为500MHz。     

α-Fe_2O_3薄膜的制备、结构和气敏特性

采用等离子增强化学气相淀积工艺(PECVD)制备出了Fe_2O_3薄膜。用X射线衍射(XRD)和扫描电子显微镜(SEM)分析了薄膜的结构、表面形貌和粒度。研究了薄膜对乙醇、液化石油气、煤气和氢气的敏感特性。结果表明所研制的薄膜对乙醇有较高灵敏度,其检测下限可达1ppm,而对液化石油气、煤气和氢气不太敏感,具有优良的选择性。     

Two-dimensional numerical computation of the structure-dependent spectral response in a 4H-SiC metal-semiconductor-metal ultraviolet photodetector with consideration of reflection and absorption on contact electrodes

A two-dimensional model of a 4H-SiC metal-semiconductor-metal(MSM) ultraviolet photodetector has been established using a self-consistent numerical calculation method.The structure-dependent spectral response of a 4H-SiC MSM detector is calculated by solving Poisson’s equation,the current continuity equation and the current density equation.The calculated results are verified with experimental data.With consideration of the reflection and absorption on the metal contacts,a detailed study involving various electrode heights(H),spacings (S) and widths(W) reveals conclusive results in device design.The mechanisms responsible for variations of responsivity with those parameters are analyzed.The findings show that responsivity is inversely proportional to electrode height and is enhanced with an increase of electrode spacing and width.In addition,the ultraviolet (UV)-to-visible rejection ratio is > 103.By optimizing the device structure at 10 V bias,a responsivity as high as 180.056 mA/W,a comparable quantum efficiency of 77.93%and a maximum UV-to-visible rejection ratio of 1875 are achieved with a detector size of H = 50 nm,S =9μm and W = 3μm.     

SF6/O2等离子体刻蚀a-C:F薄膜的研究

以SF6/O2为刻蚀气体,采用电子回旋共振等离子体反应离子刻蚀(ECR-RIE)方法进行了氟化非晶碳(a-C∶F)低介电常数薄膜的等离子体刻蚀技术研究,结果表明,a-C∶F薄膜的刻蚀速率取决于薄膜中C—CFx与CFx两类基团刻蚀过程,富C—CFx结构的a-C∶F薄膜刻蚀速率在O2含量约20%时达到最大,而富CFx结构的a-C∶F薄膜刻蚀速率随O2的增大而减小。AFM分析表明,SF6气体刻蚀a-C∶F薄膜可以有效消除薄膜表面的团聚结构。XPS能谱分析表明,SF6气体刻蚀a-C∶F薄膜样品化学组分未发生变化,而O2气体刻蚀后在样品表面形成富C的a-C∶F层。该研究结果为a-C∶F应用于超大规模集成电路层间介质工艺奠定了必要的实验基础。     

一种考虑温度时间-空间分布的解析互连延时模型

本文从热扩散方程出发,得到了互连温度时间-空间分布的解析表达式.考虑互连温度对互连电阻和Elmore延时的影响,同时提出了一种用以分析互连时间-空间温度分布效应对互连延时影响的等效内阻模型.基于所提出的模型,详细地分析了互连长度、输入信号频率和功率对互连延时的影响.所提出的互连温度分布和延时解析模型可以应用于深亚微米温度相关的互连性能分析中.     

基于改进陷阱模型的新型p型隔离层结合场板结构的4H-SiC MESFET的特性研究与优化

本文提出了一种致力于抑制表面陷阱影响的新型结构。基于能准确表征4H-SiC材料特性的物理模型和经过实验证明能较好表征表面陷阱作用机理的模型,对器件的特性进行了研究。通过与实际器件制作中主流采用的埋栅-场板结构的4H-SiC MESFET以及实验测试的器件特性的对比,本文提出的结构在整体上对器件的特性有所提高 。新结构引入的 p型隔离层能有效地抑制表面陷阱的影响并且能减小器件在大电压微波应用条件下的栅漏电容;P型隔离层结合场板结构改善了栅极边缘的电场分布,同时能减小单一使用场板结构时场板对沟道引入的附加栅漏电容; 作为微波晶体管,由于更好的抑制了表面陷阱,基于本文提出的结构的4H-SiC MESFET比埋栅-场板结构的器件具有更高的栅延迟抑制比;在实现大功率应用方面,新型结构同样能提供更高的耐压。新结构的4H-SiC MESFET的最大饱和漏电流密度为460mA/mm,在漏电压20V的栅延迟抑制比接近90%。交流特性的分析结果表明,本文提出的结构比埋栅-场板结构的器件的特征频率和最高振荡频率分别高出5%和17.8%。此外,新结构的器件能承受较高的击穿电压,进而保证了器件的大功率密度。针对本文提出的结构进行了优化,以使器件能发挥最好的微波特性并对器件的设计提供一定参考。     

CMOS反相器高功率微波脉宽扰乱效应的建模和分析

本文对受脉宽影响的过剩载流子浓度分布及高功率微波(HPM)扰乱易发性进行解析建模,并利用仿真结果和实验数据对模型进行验证。利用机理分析与模型推导,得到过剩载流子主导闩锁效应中电流放大过程的结论。结果表明,P型衬底中的过剩载流子浓度分布确与HPM脉宽有关,HPM扰乱电压阈值Vp随着脉宽增宽而减小,同时这一变化存在一个拐点,这是由于P型衬底中的过剩载流子累积效应将随着时间推移而受到抑制。文中首次提出HPM脉宽扰乱效应的物理本质是过剩载流子的累积效应。实验验证认为,Vp解析模型能够对CMOS反相器的HPM扰乱易发性进行可靠和准确的预测,并同时考虑工艺、环境温度及版图参数等因素。从模型中可以得到,版图参数LB对脉宽扰乱效应有显著影响：LB较小的CMOS反相器更容易受到HPM的扰乱,这一结论将有助于提出反相器免于HPM扰乱的加固措施。     

Strain effects on band structure of wurtzite ZnO： a GGA ＋ U study

Band structures in wurtzite bulk ZnO/Zn1-xMgxO are calculated using first-principles based on the framework of generalized gradient approximation to density functional theory with the introduction of the on-site Coulomb interaction. Strain effects on band gap, splitting energies of valence bands, electron and hole effective masses in strained bulk ZnO are discussed. According to the results, the band gap increases gradually with increasing stress in strained ZnO as an Mg content of Znl-xMgxO substrate less than 0.3, which is consistent with the experimental results. It is further demonstrated that electron mass of conduction band （CB） under stress increases slightly. There are almost no changes in effective masses of light hole band （LHB） and heavy hole band （HHB） along [00k] and [k00] directions under stress, and stress leads to an obvious decrease in effective masses of crystal splitting band （CSB） along the same directions.