The frequency and voltage dependent electrical characteristics of Al-TiW-Pd2Si/n-Si structure using I-V, C-V and G/ω-V measurements

The forward and reverse bias capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of Al-TiW-Pd₂Si/n-Si structures have been investigated over a wide frequency range of 5 kHz-5 MHz. These measurements allow to us the determination of the interface states density (N_ss) and series resistance (R_s) distribution profile. The effect of R_s on C and G is found noticeable at high frequencies. The C-V-f and G/w-V-f characteristics of studied structures show fairly large frequency dispersion especially at low frequencies due to N_ss in equilibrium with the semiconductor. The N_ss profile was obtained both forward bias current-voltage (I-V) characteristics by using into account the bias dependent of the ideality factor and effective barrier height (Φ_e) and low frequency (C_LF)-high frequency (C_HF) method. The plot of series resistance vs. voltage for the low frequencies gives a peak, decreasing with increasing frequencies. The frequency dependent C-V and G/w-V characteristics confirm that the R_s and N_ss of the Al-TiW-Pd₂Si/n-Si structures are important parameters that strongly influence the electric parameters in device.     

Transport and interface states in high-κ LaSiOx dielectric

The paper presents the results of capacitance-voltage, conductance-frequency and current-voltage characterization in the wide temperature range (140-300 K) as well as results of low temperature (5-20 K) thermally stimulated currents (TSC) measurements of metal-oxide-semiconductor (MOS) structures with a high-κ LaSiO_x dielectric deposited on p- and n-type Si(1 0 0) substrate. Interface states (D_it) distribution determined by several techniques show consistent result and demonstrates the adequacy of techniques used. Typical maxima of interface states density were found as 4.6 × 10¹¹ eV⁻¹cm⁻² at 0.2 eV and 7.9 × 10¹¹ eV⁻¹cm⁻² at 0.77 eV from the silicon valence band. The result of admittance spectroscopy showed the presence of local states in bandgap with activation energy E_a = 0.38 eV from silicon conductance band, which is in accord with interface states profile acquired by conductance method. Low-temperature TSC spectra show the presence of shallow traps at the interface with activation energies ranging from 15 to 32 meV. The charge carrier transport through the dielectric film was found to occur via Poole-Frenkel mechanism at forward bias.     

Analysis of electronic parameters and interface states of boron dispersed triethanolamine/p-Si structure by AFM, I-V, C-V-f and G/ω-V-f techniques

The electronic parameters and interface state properties of boron dispersed triethanolamine/p-Si structure have been investigated by atomic force microscopy, I-V, C-V-f and G/ω-V-f techniques. The surface topography and phase image of the TEA-B film deposited onto p-Si substrate were analyzed by atomic force microscopy. The atomic force microscopy results show a homogenous distribution of boron particles in triethanolamine film. The electronic parameters (barrier height, ideality factor and average series resistance) obtained from I-V characteristics of the diode are 0.81 eV, 2.07 and 5.04 kΩ, respectively. The interface state density of the diode was found to be 2.54 × 10¹⁰ eV⁻ cm⁻² under V_g = 0. The obtained D_it values obtained from C-V and G/ω measurements are in agreement with each other. The profile of series resistance dependent on voltage and frequency confirms the presence of interface states in boron dispersed triethanolamine/p-Si structure. It is evaluated that the boron dispersed triethanolamine controls the electronic parameters and interface properties of conventional Al/p-Si diode.     

The built-in voltage and space charge layer capacitance of p−n junctions

The accuracy of the abrupt space charge edge (ASCE) approximation is studied. It is shown that the ASCE approximation is useful for exact capacitance calculations if the built-in voltage is assumed to be dependent on the space charge layer width. The classical formula

$\text{C =}\text{?}\text{w}$

is not valid in this case. The new, general set of equations for capacitance calculation is derived. It can be used for an arbitrary impurity profile, and remains valid at forward bias and at any temperature.Analytical relationships for linearly graded junctions are presented. The capacitance is nearly a cube-root function of the applied voltage, as predicted by Shockley, but the value of the C^?3 vs U intercept with U-axis is about $\text{14kT}\text{3q}$ lower than the value obtained from the classical theory.The set of equations described in the paper can be easily solved numerically for an arbitrary impurity profile. The results of calculations for real diffused junctions are presented and compared with experiment. Some of the discrepancies between theoretical and experimental results, recently reported by Van Overstraeten and Nuyts, are explained.     

Improved electrical characteristics and reliability of amorphous InGaZnO metal-insulator-semiconductor capacitor with high κ HfOxNy gate dielectric

High κ HfO_xN_y film was deposited on amorphous InGaZnO (a-IGZO) by radio-frequency reactive sputtering using an HfO₂ target in nitrogen plus argon ambience, the electrical characteristics and reliability of a-IGZO metal-insulator-semiconductor (MIS) capacitors were investigated. Experimental results indicate that the nitrogen incorporation into HfO₂ can produce a strong nitride interfacial barrier layer, thus lead to reducing the interface state density, suppressing the hysteresis voltage, and decreasing the gate-leakage current. Improved performance has been achieved for HfO_xN_y gate dielectric a-IGZO MIS capacitors, with a interface state density of 5.1 × 10¹¹ eV⁻¹ cm⁻², a gate-leakage current density of 3.9 × 10⁻⁵ A/cm² at V_fb + 1 V, an equivalent permittivity of 24, and a hysteresis voltage of 105 mV. Moreover, the enhanced reliability of Al/HfO_xN_y/a-IGZO MIS capacitor is observed with a small degradation of electrical characteristics after a high field stressing at 10 MV/cm for 3600 s.     

NO 有效带宽的k 分布算法

一氧化氮(NO)是高超声速飞行器流场中重要组分, 对飞行器本体和流场红外辐射传输有重要影响,因此研究NO有效带宽的快速算法很有必要。根据HITEMP 2010数据库,研究了NO在1~15 m红外波段的谱线线强以及吸收系数分布特征,提出了改进的k分布模型,采用高斯数值方法快速求解;此外分析了吸收系数阈值对g-k曲线以及有效带宽的影响,提出了吸收系数阈值的选取方法。实验结果表明:文中方法计算得到的NO有效带宽与与逐线计算方法结果较为吻合,误差不超过5%;与宽带k分布算法相比,该算法计算效率更高,且当选择合适阈值时精度更高。     

Study of stress biasing effect observed in C–V characteristics of ITO/PI/TIPS-pentacene/Au diodes by electric field induced optical second harmonic generation

To clarify the capacitance–voltage (C–V  ) characteristics of organic double-layer diodes with a structure of ITO/PI/TIPS-pentacene/Au, time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurement was employed. The TR-EFISHG measurement probed the change of electric fields in the TIPS-pentacene organic layer, which originates from accumulated charges at the PI/TIPS-pentacene double-layer interface. Consequently, the shift of threshold voltage ΔV_th$\mathrm{\Delta }{V}_{\mathit{th}}$ of the C–V curves caused by stress negative-biasing was well explained, and a potential well model was proposed on the basis of the TR-EFISHG measurement. TR-EFISHG is a very useful way to study the carrier behaviors, in terms of the C–V characteristics.     

宽带光纤λ/4波片的温度特性

宽带光纤/4波片是一种特殊的变速旋转型双折射光纤。当其旋转速度由小到大逐渐增加时,可将输入的线偏振光转换为圆偏振光,同时具有理想的偏振变换带宽。结合全光纤电流互感器的光路模型,分析了宽带光纤/4波片的特性对互感器标度因数稳定性的影响。通过在邦加球上的轨迹,对宽带光纤波片快转端的本征态及两正交本征态间的耦合系数进行了实验研究,测量了其随温度的变化。实验结果表明,当波片转速变化曲线满足一定条件时,宽带光纤/4波片的温度效应对电流互感器标度因数稳定性的影响小于0.2%,远小于窄带光纤/4波片的影响。利用宽带光纤/4波片可有效提高光纤电流互感器系统的温度稳定性。     

物理诊断设备精确自φ直方法

为了获确的激光打靶实验数据,需要使用诊断搭载平台搭载物理诊断设备对打靶目标进行高精直.针对传统方法存在耗时、误差(RMS)较大的问题,根据搭载平台与物理诊断设备的特点,提出了一种基于视觉伺服的精确自直方法.首先,构建三直向量估算立体视觉系统中靶的偏差,在弱透视条件下,估算值接近于真值;然后,建立三自由度姿态调节模型,提高姿态调节精度.最后,运直向量与调节模型设计视觉伺服控制器,仅需一次离线标定即可进行快直.通过以上改进,实现了物理诊断设备的精确自直.实验结果表明,诊断设备直精度(RMS)分别为:x 指向为11m,y 指向为12m.搭载分幅相机进行激光打靶考核验证,得到了物理实验过程的X光焦斑图像,表直方法满足工程使用要求.     

γ辐射对光纤色散的影响

提出了基于能量沉积的辐射对光纤折射率的影响分析方法,计算了光纤的色散变量随光纤的V参数、折射率变化,开展了辐射对光纤色散影响的测量实验,得到了光纤的色散系数随辐射剂量变化数据。实验及理论计算结果表明:(1) 光纤的色散系数随辐射剂量的增加而增大,在一定的剂量(0~500 Gy)范围内,光纤色散增加量呈逐渐饱和趋势;(2) 辐射导致光纤折射率发生变化,从而引起材料色散的变化,辐射效应中的电子密度增大是折射率改变的主要因素;(3) 辐射感生损耗引起的信号幅度降低要比辐射感生色散引起的脉冲展宽明显,对于暴露在核辐射环境中的长距离光纤,其脉冲信号产生的畸变是两者同时存在并共同作用的结果。     

X射线分光晶体高阶衍射效率标定方法

包含高阶衍射的X射线分光晶体积分衍射效率是X射线光谱准确辨识、X射线分光晶体性能研究、X射线光谱定量测量和高分辨X射线单能成像的基础。基于X射线衍射仪,选择适当厚度的镍滤片和控制X射线管电压,极大地抑制Cu K及韧致辐射,将X射线管光源Cu K单能化。以常用的X射线分光晶体季戊四醇[PET（002）]为样品,对X射线分光晶体的高阶积分衍射效率进行标定其结果表明,在 Cu K能点,PET（002）晶体的积分衍射效率,二阶为一阶的14.36%,三阶为一阶的4.07%;Cu K1最大峰值比,二阶衍射为一阶的7.7%,三阶衍射为一阶的1.3%。基于X射线衍射仪的X射线分光晶体高阶衍射效率实验标定具有快速高效、方便灵活的特点。     

LaScO3 as a higher-κ dielectric for p-MOSFETs

The electrical properties of MOS capacitors with LaScO₃ thin films grown by molecular beam deposition (MBD) have been studied with and without post deposition annealing (PDA) in O₂ environment followed by forming gas. An EOT of 0.65 nm could be achieved for samples without PDA. However, the films suffer from large hysteresis and interface trap density. Applying PDA reduces the hysteresis, the D_it (down to the mid of 10¹¹ (eV cm²)⁻¹) and the leakage current by two orders of magnitude (down to the range of 10⁻⁴A/cm²) for an EOT of 1.1 nm. Furthermore we have successfully integrated LaScO₃ into FD MOSFETs on SOI substrates. The p-FETs with LaScO₃ show excellent characteristics with a steep subthreshold slope down to 65 mV/dec and hole mobilities comparable to HfO₂ and HfSiON.     

全光纤电流互感器λ/4波片制作工艺

根据全光纤电流互感器（FOCT）的光路结构及其工作原理,分析了/4波片的制作效果对FOCT的影响,研究了/4波片的制作工艺,得出了影响波片制作效果的主要因素。通过选择合适的材料和工艺方法,获得了性能优异的全光纤/4波片。试验结果表明:该方法制作的波片提高了FOCT的性能,使其满足了0.2 S级测量用电子式电流互感器的准确度要求。     

脉冲γ射线对光纤的辐射感生损耗

研究了光纤受射线辐照响应机制,计算了光纤对射线吸收率、效应截面、Compton电子的能通量及角度分布;提出了瞬态辐射感生损耗的测量方法,采用波长分别为405、660、850、1 310、1 550 nm的模拟宽带光纤传输系统,设计了瞬态辐射感生损耗的实验测量系统。在平均光子能量0.3 MeV、剂量率2.03107 Gy/s和平均光子能量1.0 MeV、剂量率5.32109 Gy/s的两种脉冲射线辐照条件下,获得了4种光纤瞬态辐射感生损耗与剂量的关系、永久性感生损耗的谱分布和折射率变化结果:（1）脉冲射线对光纤的瞬态辐射感生损耗随探测波长在近红外到可见光范围内的减小而增大;（2）在相同辐照条件下,多模光纤的瞬态辐射感生损耗稍大于单模光纤;（3）辐射致光纤折射率降低;（4）在一定剂量范围内,多模光纤瞬态辐射感生损耗和剂量呈近似线性关系。研究表明,射线导致光纤基质原子产生新的色心和光纤折射率降低,色心对传输光子的共振吸收导致光纤吸收损耗增加,折射率降低导致光纤波导损耗增加,感生损耗是两种机制共同作用的结果。     

A crystalline D-π-A organic small molecule with naphtho[1,2-b:5,6-b′]dithiophene-core for solution processed organic solar cells

In this work, we have designed and synthesized a new naphtho[1,2-b:5,6-b′]dithiophene-containing enlarged π-conjugated donor–acceptor (D–A) small molecule, NDT(TTz)₂, for use in solution-processed organic photovoltaics. NDT(TTz)₂, which contains a thiophene-bridged naphtho[1,2-b:5,6-b′]dithiophene as the central fused core and triphenylamine-flanked thiophene thiazolothiazole as a spacer, was synthesized via sequential Suzuki and Stille coupling reactions. The thermal, physiochemical, and electrochemical properties of NDT(TTz)₂ have been evaluated by differential scanning calorimetry, thermogravimetry, UV–Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction, and cyclic voltammetry. As desired for photovoltaic applications, NDT(TTz)₂ possesses good solubility, thermal stability, and a well-ordered, π–π stacked, crystallinity. The optical band gap and HOMO level of NDT(TTz)₂ were determined to be 2.0 eV and −5.23 eV, respectively. In addition to organic thin film transistor studies, application of NDT(TTz)₂ to preliminary photovoltaic devices has also been investigated by fabricating solution-processed bulk heterojunction solar cells together with PC₇₁BM in a typical layered device structure, ITO/PEDOT:PSS/NDT(TTz)₂:PC₇₁BM/LiF/Al. Without extensive optimization of the device, NDT(TTz)₂ in these devices shows a maximum power conversion efficiency of 1.44% under AM 1.5 illumination at a 100 mW/cm² intensity.     

高g 值加速度校准激励脉冲的横向激光干涉测量方法

为了准确测量高g值加速度传感器校准激励脉冲的幅值和持续时间,研究了基于激光多普勒的加速度脉冲测量方法。在分析激光多普勒原理的基础上,设计了以光栅为合作目标的激光测速仪;针对干涉仪输出的存在零点漂移的多普勒信号,提出了基于多项式拟合和希尔伯特变换的局部均值分解法;利用该方法对实测多普勒信号进行了解算,得到了激励加速度脉冲;分析了由干涉仪及其合作目标引起的加速度脉冲的幅值和脉宽测量不确定度。实测数据表明:该方法在包含因子k=2时幅值测量的扩展不确定度为U=3%,脉宽测量的扩展不确定度为U=4.8%。测量精度符合ISO16063-13(2001)规定的指标。     

互补S矩阵在DMD光谱仪中噪声改善的研究

提出一种对数字微镜进行互补S矩阵编码调制的新方案,经理论分析,互补S矩阵本身具有的优良性质,可将噪声改善度较S矩阵提高约2倍。通过对光谱信号建模,详细推导分析了互补S矩阵应用中的噪声改善理论,证明方案实现的过程中具有削减杂散光和暗电流噪声的作用。最后将其应用于DMD光谱仪中进行实验验证,结果表明:63阶互补S矩阵编码方案较同阶S矩阵编码方案,信噪比提高了1.69倍,与理论分析吻合。     

p值统计量建模独立性的高光谱波段选择方法

近年来，p值统计量的使用规范引起了统计学界的极大关注和集中讨论，广泛认为，p值统计量可表达观测数据与备择假设之间的不相容程度。为探究高光谱图像波段的相关分析p值与其样本独立性的联系，进行了演绎推理和实例验证，研究表明，与相关系数r统计量相比，相关分析p统计量可直接表达波段样本的独立性，且p值矩阵具有高水平的自稀疏性，便于建模和计算。进而，对相关性p值矩阵进行直方图频数统计，提出一种基于p值的高光谱自适应波段选择方法pSMBS。选取典型数据进行了监督分类实验，结果表明，在Kappa系数、总体精度（OA）和平均精度（AA）上，pSMBS均优于同类方法ABS、InfFS和LSFS。说明pSMBS在高光谱波段选择方面具有突出的有效性，这也佐证了相关性p值对波段独立性的强表征能力。     

High-speed continuous-time band pass ΔΣ modulator for class-S systems

A fully integrated continuous-time bandpass delta-sigma modulator (BPDSM) fabricated in a 0.25 μm SiGe BiCMOS is presented. It consists of a two-stage second-order resonator, high-speed comparator, multi-feedback current digital-to-analog converter, and an output buffer. The input frequency can be tuned from 3.55 to 3.9 GHz at a 9.5 GHz fixed sampling clock frequency. This modulator dissipates 109 mA from a 3.3 V power supply. The peak signal-to-noise ratio (SNR) of the sine-wave input is 37.3 dB in a 20 MHz channel bandwidth, and the error vector magnitude (EVM) of a 64QAM long-term evolution (LTE) downlink signal is 5.94% with a 10.5 dB peak-to-average-power ratio (PAPR).     

距离选通激光成像空间定位模糊C均值聚类分割法

针对距离选通激光成像对比度低、照度不均、图像模糊的特点,提出了一种基于空间定位的模糊C均值聚类方法（SPFCM）对目标进行分割。传统的模糊C均值聚类法存在以下缺点:一是需要预先获得目标分类数量,自适应性较差;二是对空间信息不敏感,导致目标轮廓不完整以及错误分类。针对上述缺陷,文中对传统算法进行了改进,引入了初定位的概念,首先利用最大类间方差法（Otsu 法）和数学形态学工具对子目标进行初步定位,再将其形心方位信息和灰度信息融合到聚类过程中,以较短的迭代过程实现不同目标的归类。实验结果证明基于空间定位的模糊C均值聚类法可以完整、有效地对距离选通激光图像进行提取分割,处理时间优于传统FCM。