Effect of substrate doping on the flatband and threshold voltages of strained-Si pMOSFET

The effect of substrate doping on the flatband and threshold voltages of strained-Si/SiGe p metal-oxide semiconductor field-effect transistor (pMOSFET) has been studied. By physically deriving the models of the flatband and threshold voltages, which have been validated by numerical simulation and experimental data, the shift in the plateau from the inversion region to the accumulation region as the substrate doping increases has been explained. The proposed model can provide valuable reference to the designers of strained-Si devices and has been implemented in software for extracting the parameters of strained-Si MOSFET.     

亚100 nm应变Si/SiGe nMOSFET阈值电压二维解析模型

本文基于二维泊松方程,建立了适用于亚100 nm应变Si/SiGe nMOSFET的阈值电压理论模型.为了保证该模型的准确性,同时考虑了器件尺寸减小所导致的物理效应,如短沟道效应,量子化效应等.通过将模型的计算结果与二维器件模拟器ISE的仿真结果进行对比分析,证明了本文提出的模型的正确性.最后,还讨论了亚100 nm器件中常规工艺对阈值电压的影响.该模型为亚100 nm小尺寸应变Si器件的分析设计提供了一定的参考. 关键词： 亚100nm 应变Si/SiGe nMOSFET 二维表面势 阈值电压     

应变SiGe p 型金属氧化物半导体场效应管栅电容特性研究

由于台阶的出现, 应变SiGe p型金属氧化物半导体场效应管 (pMOSFET) 的栅电容特性与体Si器件的相比呈现出很大的不同, 且受沟道掺杂的影响严重. 本文在研究应变SiGe pMOSFET器件的工作机理及其栅电容C-V 特性中台阶形成机理的基础上, 通过求解器件不同工作状态下的电荷分布, 建立了应变SiGe pMOSFET栅电容模型, 探讨了沟道掺杂浓度对台阶的影响. 与实验数据的对比结果表明, 所建立模型能准确反映应变SiGe pMOSFET器件的栅电容特性, 验证了模型的正确性. 该理论为Si基应变金属氧化物半导体(MOS)器件的设计制造提供了重要的指导作用, 并已成功应用于Si基应变器件模型参数提取软件中, 为Si基应变MOS的仿真奠定了理论基础. 关键词： 应变SiGe pMOSFET 栅电容特性 台阶效应 沟道掺杂     

Effects of charge and dipole on flatband voltage in an MOS device with a Gd-doped HfO_2 dielectric

Gd-doped HfO2 has drawn worldwide interest for its interesting features.It is considered to be a suitable material for N-type metal-oxide-semiconductor(MOS)devices due to a negative flatband voltage(Vfb)shift caused by the Gd doping.In this work,an anomalous positive shift was observed when Gd was doped into HfO2.The cause for such a phenomenon was systematically investigated by distinguishing the effects of different factors,such as Fermi level pinning(FLP),a dipole at the dielectric/SiO2interface,fixed interfacial charge,and bulk charge,on Vfb.It was found that the FLP and interfacial dipole could make Vfbnegatively shifted,which is in agreement with the conventional dipole theory.The increase in interfacial fixed charge resulting from Gd doping plays a major role in positive Vfbshift.     

基于双电源电压和双阈值电压的全局互连性能优化

基于双电源电压和双阈值电压技术,提出了一种优化全局互连性能的新方法.文中首先定义了一个包含互连延时、带宽和功耗等因素的品质因子用以描述全局互连特性,然后在给定延时牺牲的前提下,通过最大化品质因子求得优化的双电压数值用以节省功耗.仿真结果显示,在65 nm工艺下,针对5%,10%和20%的允许牺牲延时,所提方法相较于单电压方法可分别获得27.8%,40.3%和56.9%的功耗节省.同时发现,随着工艺进步,功耗节省更加明显.该方法可用于高性能全局互连的优化和设计. 关键词： 全局互连 双电源电压 双阈值电压 功耗     

pMOS器件直流应力负偏置温度不稳定性效应随器件基本参数变化的分析

应用负偏置温度不稳定性(negative bias temperature instability,NBTI),退化氢分子的漂移扩散模型,与器件二维数值模拟软件结合在一起进行计算,并利用已有的实验数据和基本器件物理和规律,分析直流应力NBTI效应随器件沟道长度、栅氧层厚度和掺杂浓度等基本参数的变化规律,是研究NBTI可靠性问题发生和发展机理变化的一种有效方法.分析结果显示,NBTI效应不受器件沟道长度变化的影响,而主要受到栅氧化层厚度变化的影响;栅氧化层厚度的减薄和栅氧化层电场增强的影响是一致的,决定了器件退化按指数规律变化;当沟道掺杂浓度提高,NBTI效应将减弱,这是因为器件沟道表面空穴浓度降低引起的;然而当掺杂浓度提高到器件的源漏泄漏电流很小时(小泄露电流器件),NBTI效应有明显的增强.这些结论对认识NBTI效应的发展规律以及对高性能器件的设计具有重要的指导意义.     

Temperature effect on threshold voltage and optical property of twisted nematic liquid crystal with applied different voltages

In this paper, temperature-dependent birefringence theory of liquid crystal is used to investigate the temperature effect on the threshold voltage. An expression for describing the non-linear relationship between the threshold voltage and temperature is deduced. In addition, we theoretically discuss the temperature effect on the transmitted ratio of the namatic twisted liquid crystal without the applied voltage and with the applied voltage. It is found that the transmitted ratio is decreased linearly as temperature is increased when the liquid crystal is not applied with voltage, but the transmitted ratio is increased linearly as temperature is increased when the liquid crystal is applied with voltage. The threshold voltages and the transmitted ratio are measured at different temperatures. The experimental data are consistent with the theoretical calculated results.     

纳米TiO2多孔薄膜电极平带电势的研究

采用光谱电化学方法研究了纳米TiO₂多孔薄膜电极的平带电势,获得了薄膜厚度以及TiCl₄处理对纳米TiO₂薄膜电极平带电势的影响情况,并研究了平带电势对染料敏化太阳电池光伏性能的影响.结果表明,可以通过检测纳米TiO₂电极平带电势的变化趋势来反映电池中TiO₂电极平带电势的变化趋势.随着TiO₂电极膜厚的增加,其平带电势将向正方向移动,导致对应电池的开路电压随之减小.另外,经 关键词： 平带电势 2')" href="#">纳米TiO₂ 染料敏化 太阳电池     

界面态电荷对6H碳化硅N沟MOSFET阈值电压和跨导的影响

针对界面态密度在禁带中的不均匀分布,并且考虑到碳化硅材料中杂质的不完全离化,分析了界面态电荷对N沟6H碳化硅MOSFET阈值电压和跨导的影响.结果显示界面态密度的不均匀分布不仅使阈值电压增大,而且还会导致器件跨导变低,它是影响SiCMOSFET特性的一个重要因素 关键词： 碳化硅 界面态 阈值电压 跨导     

Properties of n-Ge epilayer on Si substrate with in-situ doping technology

The properties of n-Ge epilayer deposited on Si substrate with in-situ doping technology in a cold-wall ultrahigh vacuum chemical vapor deposition(UHVCVD) system are investigated.The growth temperature of ~500℃ is optimal for the n-Ge growth in our equipment with a phosphorus concentration of ~10~(18)cm~(-3).In the n-Ge epilayer,the depth profile of phosphorus concentration is box-shaped and the tensile strain of 0.12% confirmed by x-ray diffraction measurement is introduced which results in the red shift of the photoluminescence.The enhancements of photoluminescence intensity with the increase of the doping concentration are observed,which is consistent with the modeling of the spontaneous emission spectrum for direct transition of Ge.The results are of significance for guiding the growth of n-Ge epilayer with in-situ doping technology.     

The modulation effect of substrate doping on multi-node charge collection and single-event transient propagation in 90-nm bulk complementary metal-oxide semiconductor technology

Variation of substrate background doping will affect the charge collection of active and passive MOSFETs in complementary metal-oxide semiconductor (CMOS) technologies, which are significant for charge sharing, thus affecting the propagated single event transient pulsewidths in circuits. The trends of charge collected by the drain of a positive channel metal-oxide semiconductor (PMOS) and an N metal-oxide semiconductor (NMOS) are opposite as the substrate doping increases. The PMOS source will inject carriers after strike and the amount of charge injected will increase as the substrate doping increases, whereas the source of the NMOS will mainly collect carriers and the source of the NMOS can also inject electrons when the substrate doping is light enough. Additionally, it indicates that substrate doping mainly affects the bipolar amplification component of a single-event transient current, and has little effect on the drift and diffusion. The change in substrate doping has a much greater effect on PMOS than on NMOS.     

The non-destructive threshold of the graphite surface by STM in the ultra-fast pulse mode

In this paper single ultra-fast voltage pulses are introduced to the Pt/Ir tip of a scanning tunnelling microscope (STM), and the non-destructive threshold of the graphite surface is studied systematically in a wide range of pulse durations (from 10$^{4}$ to 8\,ns). Considering the waveform distortion of the pulses at the tunnelling region, this paper gives the corrected threshold curve of pulse amplitude depending on pulse duration. A new explanation of threshold power has been suggested and fits the experimental results well.     

SiC肖特基源漏MOSFET的阈值电压

SiC肖特基源漏MOSFET的阈值电压不同于传统的MOSFET的阈值电压.在深入分析工作机理的基础上,利用二维模拟软件ISE提取并分析了器件的阈值电压.对SiC肖特基源漏MOSFET的阈值电压给出物理描述,得出当源极载流子主要以场发射方式进入沟道,同时沟道进入强反型状态,此时的栅电压是该器件的阈值电压. 关键词： 碳化硅 肖特基接触 阈值电压     

原子势对阈上电离平台的影响

本文从理论上分别研究了长程和短程原子势对阈上电离光电子谱平台结构的影响. 发现在相当大的激光参数范围内, 长程势的阈上电离谱总是呈现出清晰的双平台结构; 对于短程势, 阈上电离谱双平台的界限不再清晰, 随着入射激光强度的减小, 逐渐从双平台过渡到单平台. 基于经典分析和量子力学数值模拟, 阐明了在不同模型势下, 电离速率的差别和再散射电子弹性碰撞截面的不同导致了上述平台结构的差异．此外, 还讨论了激光脉冲空间强度分布对这一现象的影响. 关键词： 阈上电离 离子势影响 中红外激光脉冲     

掺杂浓度对硅锥阴极特性的影响

基于漂移扩散模型和量子理论中的WKB方法,用数值模拟方法分析了材料掺杂浓度对硅锥阴极场致发射特性及工作状态的影响,结果表明,硅锥阴极单纯的场致发射IemitE特性受硅材料掺杂浓度的影响很小.但低掺杂硅锥阴极顶端的电位随发射电流增大而明显上升.锥体上电位变化可以等效为一个与锥体形状与掺杂相关的串联电阻的作用,这一电阻对单尖发射电流有负反馈作用.另外,在常规的工作状态下,硅锥阴级的温升并不严重.这些结果可以作为硅锥阴极设计的参考. 关键词： 硅 掺杂 场致发射     

The effect of Fe doping on superconductivity in ZrRuP

This work reports the structure and superconducting properties of the superconductor ZrRuP doped with Fe; the ZrRu_1−xFe_xP solid solution was investigated by means of X-ray powder diffraction, SQUID magnetometry and Mößbauer spectroscopy. It is shown that the modification of the superconducting properties by doping with Fe is similar to the effect of chemical pressure and that the Fe doped compounds do not show any magnetic ordering.     

清洗对偏振分光膜损伤阈值的影响

采用微分干涉显微镜、扫描电镜和聚焦离子束观察了偏振分光膜损伤的形貌,从损伤机理出发,研究了清洗对偏振分光膜损伤阈值的影响。结果表明：清洗能有效去除表面杂质,清洗质量越好,基板上的杂质尺寸越小,杂质密度也越小,相应的偏振分光膜S光的损伤阈值越高;清洗能有效去除基板表面的纳米吸收中心,吸收性杂质分布密度越小,吸收峰越低,P光的损伤阈值越高。     

Temperature effect on the threshold frequency of absorption in a quantum pseudodot

The threshold frequency of absorption in a quantum pseudodot under the influence of temperature and applied magnetic field is calculated. The threshold frequency of absorption is computed as a function of temperature and applied magnetic field. The linear and nonlinear dependence of the absorption threshold frequency on magnetic field and temperature has been showed. According to the results obtained from the present work, we find that the linear and nonlinear dependence of the absorption threshold frequency depends on used range of the temperatures and magnetic fields.     

Vacancy effect on the doping of silicon nanowires:A first-principles study

The influence of vacancy defect on the doping of silicon nanowires is systematically studied by the first-principles calculations. The atomic structures and electronic properties of vacancies and vacancy–boron(vacancy–phosphor) complexes in H-passivated silicon nanowire with a diameter of 2.3 nm are explored. The results of geometry optimization indicate that a central vacancy can exist stably, while the vacancy at the edge of the nanowire undergoes a local surface reconstruction, which results in the extradition of the vacancy out of the nanowire. Total-energy calculations indicate that the central vacancy tends to form a vacancy–dopant defect pair. Further analysis shows that n-type doping efficiency is strongly inhibited by the unintentional vacancy defect. In contrast, the vacancy defect has little effect on p-type doping.Our results suggest that the vacancy defect should be avoided during the growth and the fabrication of devices.     

First-principles study on the effect of high In doping on the conductivity of ZnO

Based on the density functional theory (DFT), using first-principles plane-wave ultrasoft pseudopotential method, the models of the unit cell of pure ZnO and two highly In-doped supercells of Zn0.9375In0.0625O and Zn0.875In0.125O are constructed, and the geometry optimizations of the three models are carried out. The total density of states (DOS) and the band structures (BS) are also calculated. The calculation results show that in the range of high doping concentration, when the doping concentration is hihger than a specific value, the conductivity decreases with the increase of the doping concentration of In in ZnO, which is in consistence with the change trend of the experimental results.