PbS红外探测器低频噪声物理模型及缺陷表征研究

为了表征PbS薄膜光导红外探测器的材料缺陷,详细推导了1/f和产生-复合(g-r)噪声物理模型,并由实验数据验证了模型的准确性. 利用1/f噪声与表面缺陷关系,计算了不同偏压下表面陷阱密度. 得到该值随偏压升高而增加,由此得出1/f噪声与所加偏压成正比变化,与实验测试结果相一致. 在此模型基础上,研究了g-r噪声与深能级缺陷特征参量的关系,提出由低频噪声表征缺陷激活能、简并因子、俘获截面等缺陷参数的方法. 关键词： 红外探测器 1/f噪声')" href="#">1/f噪声 噪声')" href="#">g-r噪声 缺陷     

I/f noise in systems showing stochastic resonance

Stochastic resonator systems with input and/or output 1/f noise have been studied. Disordered magnets/dielectrics serve as examples for the case of output 1/f noise with white noise (thermal excitation) at the input of the resonators. Due to the fluctuation-dissipation theorem, the output noise is related to the out-of-phase component of the periodic peak of the output spectrum. Spin glasses and ferromagnets serve as interesting examples of coupled stochastic resonators. A proper coupling can lead to an extremely large signal-to-noise ratio. As a model system, a l/f-noise-driven Schmitt trigger has been investigated experimentally to study stochastic resonance with input 1/f noise. Under proper conditions, we have found several new nonlinearity effects, such as peaks at even harmonics, holes at even harmonics, and 1/f noise also in the output spectrum.     

Street categorization for the estimation of day levels using short-term measurements

Day time noise level computation by traffic noise model requires realistic traffic data that is hardly ever available for every single street, therefore direct noise levels measurements may be the alternative. However, direct, continuous measurement of the day time noise level (equivalent level from 7 am to 7 pm) is an expensive strategy if a whole city must be assessed. To overcome this situation, short-term measurements of variable duration are often taken in order to estimate the day time noise level (L_d) because they are less expensive and resource demanding than continuous measurements over a whole day or more. From a set of continuous measurements over more than 48 h in 137 streets of nine different cities, the present work quantifies the error committed when using short-term noise measurements as a function of interval length measurement. To enhance estimation accuracy, both a street categorization and a temporal categorization have been attempted: in first place, it is found that the difference between the short-term noise level and L_d follows a different distribution for main roads than for ordinary streets, therefore the error committed depends on the street category. To be specific, when estimating L_d from a 15 min short time measurement the error committed would be ±2 dB with a percent population coverage of 90%, in the case of main streets and in the case of ordinary streets the same error range covers 72.5% of the population. In second place, if the measurement range time is restricted (temporal categorization) from 9 am to 1 pm and from 2 pm to 5 pm in the case of ordinary streets, the percent population coverage increases to 90% when the error range is ±3 dB. When referring to main streets, the measurement range of time is limited from 10 am to 5 pm to obtain an increase of 2% of the percent population coverage when the error is ±1 and ±2 dB.     

一种估计半导体激光器1/f噪声参数的新方法

对含白噪声的1/f分形信号小波变换系数的方差随尺度变化的关系进行适当的变换,提出了一种基于最小二乘法的估计半导体激光器1/f噪声参数的新方法.实验表明,该方法可以有效地提取出淹没在白噪声中的激光器1/f噪声,而且估计出的噪声信号的功率谱与对比仪器的测量结果有较好的一致性. 关键词： 半导体激光器 f噪声')" href="#">1/f噪声 参数估计 小波分析     

基于小波变换和维纳滤波的半导体器件1/f噪声滤波

针对半导体器件中普遍存在的1/f噪声提出了一种结合了提升小波变换和维纳滤波器的处理方法.首先利用重新加权迭代最小二乘法拟合1/f噪声的功率谱曲线得到噪声参数的估计,从而选择恰当的小波.其次,对包含了1/f噪声的信号进行提升小波变换.考虑到小波变换对1/f噪声的白化作用,利用维纳滤波器对每一层小波系数进行处理.设计了最优全通滤波器以校正维纳滤波器的相频特性,使得小波系数经滤波后相位不变.最后利用提升小波逆变换获得被1/f噪声淹没的信号.利用实验检验了提出方法的有效性,实验数据采自用于微创外科手术机器人的力传感器.结果表明提出的方法能够有效抑制1/f噪声,并使传感器的分辨力提高了25%. 关键词： 半导体器件 f噪声')" href="#">1/f噪声 提升小波变换 维纳滤波     

基于辐照前1/f噪声的金属-氧化物-半导体场效应晶体管辐照退化模型

基于金属-氧化物-半导体场效应晶体管(MOSFET)噪声的载流子数涨落和迁移率涨落理论,建立了MOSFET辐照前1/f噪声参量与辐照后分别由氧化层陷阱和界面陷阱诱使阈值电压漂移之间的定量数学模型,并通过实验予以验证.研究结果表明,辐照诱生的氧化层陷阱通过俘获和发射过程与沟道交换载流子,在引起载流子数涨落的同时也通过库仑散射导致沟道迁移率的涨落,因此辐照前的1/f噪声幅值正比于辐照诱生的氧化层陷阱数.利用该模型对MOSFET辐照前1/f噪声与辐照退化的相关性从理论上 关键词： f噪声')" href="#">1/f噪声 辐照 金属-氧化物-半导体场效应晶体管 陷阱     

Flicker noise in degenerately doped Si single crystals near the metal-insulator transition

In this paper we report some of the important results of experimental investigations of the flicker noise near the metal-insulator (MI) transition in doped silicon single crystals. This is the first comprehensive work to study low-frequency noise in heavily doped Si over an extensive temperature range (2 K<T<500 K). The measurements of conductance fluctuations (flicker noise) were carried out in the frequency range 10⁻²<f<4 × 10¹ Hz in single crystalline Si across the MI transition by doping with phosphorous and boron. The magnitude of noise in heavily doped Si is much larger than that seen in lightly doped Si over the whole temperature range. The extensive temperature range covered allowed us to detect two distinct noise mechanisms. At low temperatures (T<100 K) universal conductance fluctuations (UCF) dominate and the spectral dependence of the noise is determined by dephasing the electron from defects with two-levels (TLS). At higher temperatures (T>200 K) the noise arises from activated defect dynamics. As the MI transition is approached, the 1/f spectral power, typical of the metallic regime, gets modified by the presence of discrete Lorentzians which arise from generation-recombination process which is the characteristic of a semiconductor.     

Current noise and long time tails in biased disordered random walks

We calculate the mean velocity and the velocity correlation function for a random walk with a uniform bias on a disordered chain. We find a new long time tail in the velocity correlation function due to the combined effects of the bias and of the disorder in the site variables. This long time tail persists to a low-frequency cutoff inversely proportional to the square of the bias. By associating the velocity correlation function with the spectrum of current fluctuations, we calculate the excess low-frequency current noise associated with this long time tail. The spectrum of current fluctuations goes as(I ²/N)f ^–1/2, whereI is the DC current,N is the number of charge carriers, andf is the frequency. The possible connection to 1/f noise is discussed. The calculation is done by a perturbation expansion in the strength of the disorder, but is shown to be exact to all orders for weak enough bias.Supported by a fellowship of the German Academic Exchange Service (DAAD).Supported by the National Science Foundation through Grant No. DMR-8108328 and through the Cornell Materials Science Center.     

Deviation of 1/f voltage fluctuations from scale-similar Gaussian behavior

Recent measurements on thin metal films suggest a pulse model of resistance fluctuations in which scale similarity and power law spectra are only approximate. We show that such a pulse model is consistent with stationary Gaussian resistance fluctuations. This is to be contrasted with the phenomenological behavior, of fluctuations near phase transitions and in turbulent fluids where the fluctuations are non-Gaussian, but exhibit scale similarity of deep physical origin. We then critically examine other tests of the Gaussian behavior of the fluctuating voltageV(t) across a resistor. These include the relaxation of the conditional mean V(t)¦V(0)=V ₀, and the spectrum ofV ²(t). We consider also the question of time reversal invariance. We further ask under what conditions 1/f noise can be measured through fluctuations of the Johnson noise power with no applied voltage. We emphasize that this possibility, suggested and observed by Voss and Clarke, requires thatV(t) contain a non-Gaussian component.     

光电耦合器电离辐射损伤电流传输比1/f噪声表征

在研究光电耦合器电离辐射损伤机理基础上,分别建立光电耦合器电离辐射损伤电流传输比(CTR)表征模型和1/f噪声表征模型.结果表明CTR退化和噪声增加都归因于辐射后光敏三极管集电结和发射结处SiO₂/Si界面缺陷增多.根据CTR退化和噪声变化分别与辐射剂量的关系,建立起噪声变化与CTR退化之间的关系,辐照实验对表征模型正确性进行了验证.运用噪声变化与辐射剂量的关系,通过低剂量辐照实验可以预测高剂量辐射后光电耦合器退化程度,故可用于评价光电耦合器抗辐射能力. 关键词： f噪声')" href="#">1/f噪声 光电耦合器 缺陷 模型     

60Co γ-射线辐照对肖特基二极管1/f噪声的影响

在肖特基二极管(Schottky barrier diode,SBD)辐照损伤机理和总剂量效应分析的基础上,利用1/f噪声的迁移率涨落和载流子数涨落模型,深入研究辐照损伤对器件1/f噪声的影响. 研究结果表明,辐照诱生新的界面态,改变界面态密度分布,进而调制了肖特基势垒高度,增大表面复合速度是引起器件性能退化主要原因,也是1/f噪声剧烈增加的主要原因. 正因为如此,噪声与器件退化存在相关性,即噪声拟合参数B越大,偏离标准值越多,器件可靠性越差,抗辐照 关键词： 肖特基二极管 f噪声')" href="#">1/f噪声 60Co γ射线')" href="#">⁶⁰Co γ射线 界面态     

Quality assessments of electrochromic devices: the possible use of 1/<Emphasis Type="Italic">f</Emphasis> current noise

Electrochromic (EC) devices, capable of modulating their optical transmittance by charge insertion/extraction, were produced by laminating films comprised of nanoporous W oxide and Ni–V oxide by a polymer electrolyte and having this three-layer stack between transparent conducting In₂O₃:Sn films backed by polyester foils. 1/f noise in the current (I) was observed when the charged (colored) EC device was discharged via a resistor. The power spectral density S _i at fixed frequency scaled as S _i  ∼ I ². Extended color/bleach cycling degraded the optical quality and homogeneity of the device and concomitantly increased the 1/f noise intensity. These initial data indicate that 1/f noise has a potential to serve as a quality measure for EC devices.     

Structure changes induced by external multiplicative noise in the electrohydrodynamic instability of nematic liquid crystals

We study the influence of external multiplicative noise on the electrohydrodynamic instability (EHD) in nematic liquid crystals. It turns out that the correlation time _n and the intensityQ of the noise are the crucial parameters to control the system. Different types of noise lead to minor quantitative changes when compared to Gaussian white noise, leaving the qualitative aspects unchanged. With increasing noise intensity the threshold for the onset of the first instability changes drastically. We observe that the curvature arising when the threshold of the various instabilities is plotted as a function of the noise intensity changes as one is going, e.g., from the onset of Williams domains (WD) to the onset of the grid pattern (GP). This result reflects the transition in the flow structure from two-dimensional (WD) to three-dimensional (GP, DSM) flow patterns. As the intensity of the noise is increased further, the onset of the first instability becomes more complex. The measurement of the nonlinear onset time shows a strong dependence on the noise intensityQ, which is linear for WD and GP well above onset. The linear onset time shows an unexpected dependence on the noise intensity close to the onset of the first instability. For sufficiently long correlation times of the noise, a destabilization by noise is obtained.     

金属氧化物半导体场效应管热载流子退化的1/fγ噪声相关性研究

研究了金属氧化物半导体(MOS)器件在高、中、低三种栅压应力下的热载流子退化效应及其1/f^γ噪声特性.基于Si/SiO₂界面缺陷氧化层陷阱和界面陷阱的形成理论,结合MOS器件1/f噪声产生机制,并用双声子发射模型模拟了栅氧化层缺陷波函数与器件沟道自由载流子波函数及其相互作用产生能级跃迁、交换载流子的具体过程.建立了热载流子效应、材料缺陷与电参量、噪声之间的统一物理模型.还提出了用噪声参数Sf ^{关键词： 金属氧化物半导体场效应管 热载流子 fγ噪声')" href="#">1/fγ噪声}     

The phase transition in the discrete Gaussian chain with 1/r 2 interaction energy

We exhibit a phase transition from a rough high-temperature phase to a rigid (localized) low-temperature phase in the discrete Gaussian chain with 1/r ² interaction energy. This transition is related to a localization transition in the ground state for a quantum mechanical particle in a one-dimensional periodic potential, coupled to quantum 1/f noise.This paper is dedicated to J. L. Lebowitz on the occasion of his 60th birthday     

非高斯噪声激励下含周期信号FitzHugh-Nagumo系统的响应特征

研究了非高斯噪声激励下含周期信号的FHN模型的动力学行为. 通过计算神经元的平均响应时间、观察神经元的共振活化和噪声增强稳定现象,分析了非高斯噪声对神经元动力学行为的影响. 发现通过改变非高斯噪声的相关时间可以有效地改变共振活化和噪声增强稳定现象. 观察到在强相关噪声下不同强度的非高斯噪声抑制了神经元的噪声增强稳定现象而共振活化现象几乎不变,也就是非高斯噪声有效地增强了神经响应的效率. 观察了平均响应时间与非高斯噪声参数q之间的关系,当q为一个有限的小于1的值时,平均响应时间取得最小值. 最后表明在一定条件下,非高斯噪声出现重尺度现象,即非高斯噪声产生的效果可以由高斯白噪声来估计. 关键词： FHN神经系统 非高斯噪声 平均响应时间 共振活化现象     

Excess noise in a hopping model for a resistor with quenched disorder

We consider a model for independent charged particles, hopping on a lattice with static disorder in the waiting times. The excess current noise is calculated and shown to be related to resistance noise and arising from mobility fluctuations. It is also related to the four point super-Burnett-function. The strength of the noise is calculated at small frequencies for weak disorder (classical long time tails) and for strong disorder, when it may behave like I/f. In that case the Hooge factor equals the fraction of deep trapping centers.     

Equivalent magnetic noise in magnetoelectric Metglas/Pb(Mg1/3Nb2/3)O3‐PbTiO3 laminate composites

We have experimentally and theoretically investigated the equivalent magnetic noise in a magnetoelectric Metglas/ 0.7Pb(Mg_1/3Nb_2/3)O₃‐0.3PbTiO₃ laminate sensor unit by considering the constituent noise sources of dielectric loss (N_DE) and DC leakage resistance (N_R). In the low frequency range (f = 1 Hz), theory predicts that N_R dominates the noise charge (1.6 times larger than N_DE), with a 1 Hz noise of 9.1\;{\rm pt}/\sqrt {\rm Hz}. The experimental equivalent magnetic noise was 10.8\;{\rm pt}/\sqrt {\rm Hz}. This observed value is slightly higher than the predicted one, which might be due to an oversimplification of the theoretical model in terms of electrical charge amplifier and external vibration noise sources. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

简谐速度噪声及其与势场之间的频率共振

为了描述复杂的噪声环境，考虑了一种具有频率结构的噪声——简谐速度噪声，包括它的产生、关联函数、功率谱以及作为热噪声时的频率特性所导致的一些行为.结果表明：在频谱空间中简谐速度噪声是一种带通噪声，存在一个峰值频率，且噪声带宽由参量Γ控制.当简谐势中的一个布朗粒子受热简谐速度噪声驱动时，粒子能量极大值出现在两种频率相等的情况下.这表明噪声和势场的频率之间存在动力学共振，决定着粒子能量的大小. 关键词： 简谐噪声 简谐速度噪声 功率谱 频率共振     

Ballistic diffusion induced by non-Gaussian noise

In this letter,we have analyzed the diffusive behavior of a Brownian particle subject to both internal Gaussian thermal and external non-Gaussian noise sources.We discuss two time correlation functions C(t) of the non-Gaussian stochastic process,and find that they depend on the parameter q,indicating the departure of the non-Gaussian noise from Gaussian behavior:for q ≤ 1,C(t) is fitted very well by the first-order exponentially decaying curve and approaches zero in the longtime limit,whereas for q 1,C(t) can be approximated by a second-order exponentially decaying function and converges to a non-zero constant.Due to the properties of C(t),the particle exhibits a normal diffusion for q ≤ 1,while for q 1 the non-Gaussian noise induces a ballistic diffusion,i.e.,the long-time mean square displacement of the free particle reads [x(t)-x(t)]2∝t2.