PZT薄膜电滞回线测试的数值补偿研究

通过Sawyer-Tower测试电路研究了铁电薄膜的电滞回线,发现薄膜漏电阻以及示波器输入电阻和电容的影响可能会使所测量的电滞回线发生形状扭曲或者使测量结果出现较大偏差,通过数值补偿方法重建了电荷平衡方程,并编制了相应的软件补偿程序。通过对溶胶-凝胶制备的PZT铁电薄膜的电滞回线测试表明,运用该数值补偿方法可以有效补偿薄膜漏电阻以及示波器输入电阻和电容对测试结果的影响,满足PZT铁电薄膜制备技术以及微机电系统中器件设计对薄膜性能测试的要求。     

去离子水清洗工艺对PZT铁电电容性能的影响

采用磁控溅射制备了结构为Pt/PZT/Pt/Ti/SiO2/Si的PZT铁电电容,并对样品用去离子水处理,通过测试其电滞回线以及漏电流,并结合XPS分析,研究了去离子水对PZT铁电电容的性能影响.结果表明,在去离子水清洗后,由于在PZT表面有吸附,PZT电容电滞回线沿电压轴发生漂移,电子势垒降低,漏电流增大,经过高温热...     

基于原子力显微技术的PZT薄膜铁电性能研究

针对现有测试技术不能直接获得纳米尺度铁电薄膜电滞回线的问题,提出了将原子力显微镜与铁电分析仪连用的方法,研究了锆钛酸铅(PZT)薄膜样品的电滞回线.结果表明,应用铁电分析仪与原子力显微镜联用的测试技术能表征铁电薄膜的电滞回线,在无顶电极测试条件下,测试得到的电滞回线很不对称,且剩余极化值较大.     

睾酮对内皮细胞表达细胞因子的影响

针对现有测试技术不能直接获得纳米尺度铁电薄膜电滞回线的问题,提出了将原子力显微镜与铁电分析仪连用的方法,研究了锆钛酸铅(PZT)薄膜样品的电滞回线.结果表明,应用铁电分析仪与原子力显微镜联用的测试技术能表征铁电薄膜的电滞回线,在无顶电极测试条件下,测试得到的电滞回线很不对称,且剩余极化值较大.     

基于可控剥离技术的柔性PZT薄膜的制备及其铁电性质

可控剥离技术(CST)作为一种薄膜制备方式已被广泛应用于柔性领域,例如硅基柔性太阳电池等。首先采用溶胶-凝胶法先后在普通硅基底上制备镍酸镧(LaNiO3)缓冲层和锆钛酸铅(PZT)薄膜。通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)进行材料表征,发现PZT薄膜结晶良好,而且表面致密均匀,表明LaNiO3缓冲层有利于PZT薄膜的成膜。之后通过基于电镀镍方法的可控剥离技术实现了硅基底柔性PZT薄膜的制备。PZT薄膜弯曲之后,采用铁电测试仪测试了电滞回线。电滞回线表明该PZT薄膜的极化强度随着施加电压的增加而增大,而且随着电压的增加,电滞回线逐渐趋于饱和,饱和极化强度为38μC/cm~2。最终得出该柔性PZT薄膜不仅具有良好的机械性能,而且具有很好的铁电性能。     

均匀设计法研究PZT铁电薄膜制备工艺的优化

应用射频磁控溅射工艺在Pt/Ti/SiO2/Si衬底上制备具有钙钛矿结构的PZT铁电薄膜。对影响PZT薄膜性能、形貌的工作气压、基片温度、氧/氩 氧之比、溅射功率、退火温度5个主要因素进行分析,在其允许范围和精度内设置5个水平,并根据均匀设计理论对该5因素及5水平进行均匀设计。不同温度下退火之后测定了PZT薄膜的厚度、SEM表面形貌、电容、介电损耗、电滞回线(包括矫顽场强、饱和极化强度、剩余极化强度)等。最后对响应结果进行多元二次线性回归,得出了回归方程。探讨达到最优化薄膜特性所需要的工艺条件。     

Au／PZT／p-Si结构铁电存储二极管的制备及其性能

采用准分子脉冲激光沉积(PLD)工艺,制备了Au／PZT／p-Si结构铁电存储二极管.在氧气氛350℃低温沉积、原位530℃快速退火工艺条件下,获得了多晶纯钙钛矿结构的Pb（Zr0.52Ti0.48）O3（PZT）铁电薄膜.PZT薄膜的铁电性能测试显示较饱和的、不对称的电滞回线,其剩余极化和矫顽场分别为13μC／cm2和48kV／cm.从C-V和I-V特性曲线观察到源于铁电极化的回滞现象,记忆窗口约1.1V,＋4V偏压下电流密度为3.9×10－6A／cm2.     

Au/PZT/p-Si结构铁电存储二极管的制备及其性能

采用准分子脉冲激光沉积 (PL D)工艺 ,制备了 Au/ PZT/ p- Si结构铁电存储二极管 .在氧气氛 35 0℃低温沉积、原位 5 30℃快速退火工艺条件下 ,获得了多晶纯钙钛矿结构的 Pb (Zr0 .5 2 Ti0 .48) O3(PZT)铁电薄膜 . PZT薄膜的铁电性能测试显示较饱和的、不对称的电滞回线 ,其剩余极化和矫顽场分别为 13μC/ cm2和 48k V/ cm.从C- V和 I- V特性曲线观察到源于铁电极化的回滞现象 ,记忆窗口约 1.1V,+4 V偏压下电流密度为 3.9× 10 - 6 A/cm2 .     

Au/BIT/PZT/BIT/p-Si(100)存储器

利用准分子激光原位淀积方法制备了BIT／PZT／BIT，PZT／BIT和BIT层状铁电薄膜，获得了电流密度－电压（I－V）回线和极化强度P－V电滞回线。在这三种结构中，Au/BIT/PZT/BIT/p-Si(100）结构的界面电位降、内建电压及频率效应是最小的。在电压转变电VT、饱和极化强度Ps及矫顽场Vc之间有三种关系，他们与I－V回线及P－V回线的关系相匹配，这种匹配关系使得以I－V回线操作的存储器将能够非挥发和非破坏读出及具有保持力。     

Hf0.5Zr0.5O2基铁电电容器的特性研究

利用原子层淀积工艺制备了9 nm厚的铪锆氧(Hf0.5Zr0.5O₂)铁电薄膜。通过淀积TiN顶/底电极形成Hf0.5Zr0.5O₂铁电电容,研究退火工艺和机械夹持工艺对铁电电容性能的影响。实验结果表明,极化强度-电压曲线为电滞回线形,双倍剩余极化强度达31.7 μC/cm²,矫顽电压约为1.6 V,电学性能明显提高。在150 ℃高温下,Hf0.5Zr0.5O₂基铁电电容器的电学性能仍然良好,证明了退火工艺和机械夹持工艺对电学性能的优化作用。     

氧化热处理SrTiO3压敏电阻的电容弥散频率

经测量氧化热处理后SrTiO3压敏电阻的电容频率和复阻抗,结果表明:升高热处理温度提高压敏电压时,电容弥散频率显著降低,晶粒电阻明显增大。由电容频谱曲线的主要特征判断,界面驰豫极化机制主导这一电容弥散区。界面驰豫方程确定的特征驰豫时间和电容弥散频率计算式,与晶粒和晶界的电物理参数相关,弥散频率的计算值与实验结果定性相符。热处理温度升高使氧过度向晶粒体内扩散,导致晶粒电阻明显增大,是弥散频率降低的主要原因。     

A compact C–V model for 120 nm AlGaN/GaN HEMT with modified field dependent mobility for high frequency applications

We present a theoretical model of AlGaN/GaN high electron mobility transistor (HEMT) that includes the effect of spontaneous and piezoelectric polarization. Present model also incorporates the effect of mole fraction dependent mobility, saturation velocity and the accurate 2-DEG density in HEMT as a function of gate voltage in subthreshold, linear and saturation regimes. This paper reports a detailed 2-D analysis of capacitance–voltage (C–V) characteristics. The contribution of various capacitances including fringing field capacitance on the performance of the device is also shown. The model further predicts the transconductance, drain conductance and frequency of operation and is in close proximity with the experimental data which confirms the validity of proposed model.     

2.5 mW 370mV/pF 高线性度不受寄生电容影响的全对称电容式传感器读出电路

本文提出了一种不受寄生电容影响的适用于电容式传感器的全对称电容电压转换电路。通过引入参考支部实现了对称的读出电路结构,线性输入的范围从而得到增大,两个运放的系统失调也相互抵消,共模点的噪声干扰和偶次谐波得到了抑制。窄波技术的运用进一步减小了运放失调和闪烁噪声的影响。Verilog-A模型的容抗管用来模拟真实的可变待测电容。仿真结果表明该电路的输出电压能够准确的响应待测电容在1KHz频率下的变化。该芯片采用片上金属绝缘金属电容阵列来进行测试。测试结果表明电路的灵敏度为370mV/pF,非线性误差在1%以下,功耗为2.5mW,该电路可以响应由FPGA控制的每隔1ms变化的电容传感阵列。     

激光二极管正向电特性的精确检测

采用正向交流特性结合I-V特性的方法,检测了激光二极管的串联电阻、理想因子、结电压和结电容与外加电压或电流的关系.首次发现,激光二极管的结电压、串联电阻、理想因子和结电容在阈值附近同时出现了明显的阶跃,之后结电压呈现饱和.此外还观察到,在较低的测试频率和较大的正向电压下,激光二极管的结电容具有负值.     

Effect of temperature on the capacitance–frequency and conductance–voltage characteristics of polyaniline/p-Si/Al MIS device at high frequencies

A polyaniline/p-Si/Al MIS device has been fabricated by forming a polyaniline layer on Si by using the electrochemical polymerization method. The conductance–voltage and capacitance–frequency measurements have been performed as a function of temperature. The capacitance of the device decreased with increasing frequency. The increase in capacitance results from the presence of interface states. The peaks have been observed in the conductance curves of the device and attributed to the presence of an interfacial layer between polyaniline and p-Si. For each temperature, the plot of series resistance/voltage gave a peak. The voltage and temperature dependence of series resistance has been attributed to the particular distribution density of interface states and the interfacial insulator layer.     

瞬态过电压抑制技术的研究

从压敏电阻与滤波电容、电感组合着手,进行理论分析,得出当压敏电阻与电感结合时,能使限制电压得到衰减,进而提出压敏电阻与T型低通滤波器相结合,在合适的参数配合下,能使瞬态过电压得到削弱.给出了在混合波模拟的雷电浪涌情况下,随电容变化和随电感变化的压敏电压和输出电压波形,同时指出针对实际情况,可以对低通滤波电路进行改进.     

对称单微隙放电管

研制了一种具有对称结构的单微隙放电管 ,研究了它的电特性。结果表明这种对称微隙放电管的耐冲击电流能力大于 15 0 0 A、极间电容小于 1p F、冲击击穿电压约 40 0 V。它可以克服非对称单微隙放电管在直流击穿电压对称性和稳定性方面的缺陷。     

Lateral effects in high-speed photodiodes

The effect of the sheet resistance of the diffused region of a p-n junction photodiode on the diode response is discussed. A differential equation is obtained for diffused region potential in terms of its sheet resistance and the manner in which the diode is illuminated. For zero external bias and low light levels or for large back-bias, the differential equation is linear. The linear equation has been solved for steady illumination and for sinusoidally varying illumination, both falling uniformly on the diode. Current voltage equations and equivalent circuits are obtained for these cases. In the ac case, the equivalent series resistance due to the diffused region sheet resistance and equivalent junction capacitance are found to be frequency dependent. The frequency dependence is interpreted as a decrease in effective diode area at high frequencies. The frequency at which this effect begins to be important is the reciprocal of the product of the diffused region sheet resistance, the junction capacitance per unit area, and the square of the diode width. The effect is slightly dependent on diode and contact geometry; both linear and circular geometries are discussed.     

Analytical voltage dependence of an unsaturated MESFET's gatecapacitance

Using a one-dimensional gradual channel analysis, the authors derive an analytical expression for the gate-source capacitance of an unsaturated MESFET as a function of the applied drain and gate voltages. Experimental measurements of the dependence of the gate-source capacitance on drain voltage show good agreement with theory when the device is biased below saturation. As the MESFET is biased into saturation the measured capacitance decreases with increasing drain voltage at a slightly faster rate than that predicted by the gradual channel theory due to high-field effects. These results show that the derived analytical expression may be useful for the analysis of the characteristics of MESFET's that are biased in the linear region     

一种精确检测半导体二极管正向电特性的新方法

提出了一种基于串联模式精确地检测半导体二极管正向电特性的新方法.利用该方法,不仅可以得到二极管在不同电压下的串联电阻、结电容、结电压、理想化因子等值,还能判断一个实际的二极管有无界面层存在并得到其界面层阻抗值.用此方法对Ni/ n- Ga N肖特基二极管进行了检测,所有的实验结果与理论分析相符合.实验中确认了在Ga N肖特基二极管中结的负电容和具有非线性电阻和电容的界面层的存在.