电驱动金刚石对顶砧低温连续加压装置

采用电驱动压电陶瓷取代传统机械螺丝给金刚石对顶砧施加压力,设计制备了低温下可连续增加流体静压的金刚石对顶砧压力装置,实现了低温(19±1)K连续加压达到4.41 GPa.该装置具有电驱动方便灵活、调谐精度高的低温连续加压功能.利用该装置实现了InAs单量子点发光与微腔腔模的共振耦合调谐过程.该装置将在原位压力精确调谐及测量样品信号跟踪等实验得到应用.     

Application of Passive Schemes for Pyroelectric Conversion of Low-Potential Heat

The paper presents the results of experimental pyroelectric studies of PZT piezoceramics by the methods of open-circuit voltage and short-circuit current. Pyroresponses resulted from action of modulated laser radiation on a pyroelement. It is shown that using altering the temperature of even a single pyroelement by 8.5 K enables production of a maximum electricenergy output power of about 16 μW on a 10 MΩ resistor at an open-circuit voltage of ～ 90 V and a short-circuit current of ～ 0.18 μA. The presented research contributes to the development of pyrogenerators for conversion of thermal energy using commercially available piezo-ceramics.     

Au/PZT/BIT/p-Si异质结的制备与性能研究

采用脉冲激光沉积(PLD)工艺,制备了以Bi₄Ti₃O₁₂(BIT)为过渡阻挡层的Au/PZT/BIT/p-Si异质结.研究了BIT铁电层对Pb(Zr_0.52Ti_0.48)O₃(PZT)薄膜晶相结构、铁电及介电性能的影响,对Au/PZT/BIT/p-Si异质结的导电机制进行了讨论.氧气氛530℃淀积的PZT为多晶铁电薄膜,与直接淀积在Si基片上相比,加入BIT铁电层后PZT铁 关键词： 铁电薄膜 异质结构 脉冲激光沉积(PLD)     

High temperature property studies of the 6H-SiC MOS capacitor

N-type and p-type 6H-SiC metal oxide semiconductor (MOS) capacitor samples are fabricated with a typical method,and the high frequency capacitor voltage (C-V) curves of these samples are measured at temperatures ranging from 293 to 533 K.There exists huge difference between the n-type and p-type samples.Flat-band voltage shift of the n-type sample becomes larger with temperature rising,but that of the p-type sample have very little change.This may be caused by the residual Al in the p-type oxide.Both types ...     

Si(100)衬底上n-3C-SiC/p-Si异质结构研究

利用LPCVD方法在Si(100)衬底上获得了3C-SiC外延膜,扫描电子显微镜(SEM)研究表明3C-SiC/p-Si界面平整、光滑,无明显的坑洞形成。研究了以In和Al为接触电极的3C-SiC/p-Si异质结的I-V,C-V特性及I-V特性的温度依赖关系,比较了In电极的3C-SiC/p-Si异质结构和以SiGe作为缓冲层的3C-SiC/SiGe/p-Si异质结构的I-V特性,实验发现引入SiGe缓冲层后,器件的反向击穿电压由40V提高到70V以上。室温下Al电极3C-SiC/p-Si二极管的最大反向击穿电压接近100V,品质因子为1.95。     

(111)取向生长Pb(Zr0:95Ti0:05)O3纳米晶薄膜的铁电与热释电特性

" 在Pt/Ti/SiO2/Si基片上用溶胶-凝胶法与快速退火工艺制备了300 nm厚的锆钛酸铅Pb(Zr0:95Ti0:05)O3 (PZT95/5)反铁电薄膜．结果显示600~700 ℃晶化处理的钙钛矿PZT95/5薄膜具有高度(111)取向生长特性．薄膜的电性能测量采用金属-铁电-金属电容器结构．在20 V电压作用下,600~700 ℃晶化处理的PZT95/5薄膜显示出饱和电滞回线．在1 kHz下,600、650和700 ℃晶化的薄膜介电常数与损耗分别为519与0.028、677与0.029、987     

Influence of mobile charged defects on the dielectric non-linearity of thin ferroelectric PZT films

The capacity-voltage (C-V) characteristics of thin ferroelectric PZT films are investigated, varying the rate of change of the control voltage in a wide range. It is established that the distance between the maxima of the C-V characteristics decreases as the rate of the voltage change is decreased. This effect is caused by the decrease of the coercive field due to the spatial separation of mobile charge carriers under the action of the control field and the accumulation of charged defects in the near-electrode regions of the films. Parameters characterizing the formation of the bulk charge in the films (concentration and mobility of oxygen vacancies) are estimated. The estimations made are consistent with the literature data.     

载流子复合及能量无序对聚合物太阳电池开路电压的影响

聚合物太阳电池中载流子的复合与能量无序对器件的开路电压有着深刻的影响.本文同时研究了基于传统富勒烯(PC71BM)和非富勒烯(O-IDTBR)电子受体的聚合物太阳电池.通过交流阻抗谱、低温电流密度-电压谱、瞬态光电压以及电致发光光谱等手段重点研究了载流子复合及能量无序对电池器件开路电压的影响.具体地,交流阻抗谱和瞬态光电压测试结果表明,富勒烯体系载流子复合损失较为严重.电致发光光谱研究显示,PC71BM器件的发光峰随着注入电流的增加不断向短波长处移动,而O-IDTBR体系发光峰位置基本不变,该结果证明PC71BM体系中能量无序度更高.载流子复合严重及能量无序度更高共同作用导致了富勒烯器件开路电压的降低.     

偏置电压对磁致伸缩/压电层合换能结构磁电性能影响

分析和测试了偏置电压调整时PZT5/Terfenol-D/PZT8层合换能结构磁电性能. 提出了一种磁致伸缩/压电层合磁电换能结构的一阶谐振频率控制方法. 通过改变压电驱动层的直流电压对磁电层合结构的预应变进行改变, 从而调整谐振频率. 分析偏置电压、 应变、 弹性模量、 谐振频率和谐振磁电电压系数之间关系. 分析表明: 在较小应变情况下, 控制电压几乎可以线性调节谐振频率, 而层合结构谐振磁电电压系数几乎与偏置电压无关. 实验研究验证: 理论与实验结果较好吻合. 在-170 V-+170 V的偏置电压时, 谐振频率可以几乎线性调整. 最大频率调整量达到1 kHz, 偏置电压对一阶纵振频率的控制率达到: 2.94 Hz/V. 在偏置磁场为0-225 Oe时, 谐振频率调整量与偏置磁场无关. 偏置磁场会改变谐振磁电电压系数, 在大于178 Oe静态磁场偏置时, 磁电电压系数最大, 达到1.65 V/Oe.     

大气压氩气/空气针-环式介质阻挡放电发射光谱诊断

为了更加深入地了解氩气/空气等离子体射流内的电子输运过程及化学反应过程,通过针-环式介质阻挡等离子体发生器在放电频率10 kHz,一个大气压条件下对氩气/空气混合气进行电离并产生了稳定的等离子体射流。通过发射光谱法对不同峰值电压下氩气/空气等离子体射流的活性粒子种类、电子激发温度及振动温度进行了诊断。结果表明,射流中的主要活性粒子为N₂的第二正带系、Ar Ⅰ原子以及少量的氧原子,其中N₂的第二正带系的相对光谱强度最强、最清晰,在本试验的发射光谱中没有发现N+₂的第一负带系谱线,这说明在氩气/空气等离子体射流中几乎没有电子能量高于18.76 eV的自由电子。利用Ar Ⅰ原子激发能差较大的5条谱线做最小二乘线性拟合对等离子体射流的电子激发温度进行了计算,得到大气压氩气/空气等离子体射流的电子激发温度在7 000~11 000 K之间。随峰值电压的增大,电子激发温度表现出先增大后减小的变化趋势,这说明电子激发温度并不总是随峰值电压的增长单调变化的。通过N₂的第二正带系对等离子体振动温度进行了诊断,发现大气压氩气/空气等离子体射流振动温度在3 000~4 500 K之间,其随峰值电压的增大而减小,这意味着虽然峰值电压的提高可有效提高自由电子的动能,但当电子动能较大时自由电子与氮分子之间的相互作用时间将会缩短,进而二者之间的碰撞能量转移截面将会减小,从而导致等离子体振动温度的降低。     

铁电SBN薄膜电光系数的测量及其在波导中的应用

利用溶胶-凝胶法在MgO(001)衬底上获得C轴择优取向的铁电铌酸锶钡(SBN)薄膜,主要介绍MgO(001)衬底上SBN60薄膜及掺入的K离子与Nb离子摩尔比例为1：3的SBN60薄膜横向电光系数r51的测量,实验测得不掺K的SBN60薄膜r51值为37．6pm／V,掺K的r51值为58．5pm／V。并由此设计一种基于MgO(001)衬底上的马赫一曾德尔型SBN60薄膜波导调制器,计算出在633nm时,掺K比例为1：3的此种波导调制器半波调制电压值为10V,不掺K的半波电压值为16V,结果说明掺入K离子能增加薄膜的横向电光系数并有效的减少波导的半波调制电压。     

Investigation of the free volume and ionic conducting mechanism of poly（ethylene oxide）-LiClO_4 polymeric electrolyte by positron annihilating lifetime spectroscopy

The positron annihilation lifetime and ionic conductivity are each measured as a function of organophilic rectorite（OREC） content and temperature in a range from 160 K to 300 K.According to the variation of ortho-positronium（o-Ps） lifetime with temperature,the glassy transition temperature is determined.The continuous maximum entropy lifetime（MELT） analysis clearly shows that the OREC and temperature have important effects on o-Ps lifetime and free volume distribution.The experimental results show that the temperature dependence of ionic conductivity obeys the Vogel-Tammann-Fulcher（VTF） and Williams-Landel-Ferry（WLF） equations,implying a free-volume transport mechanism.A linear least-squares procedure is used to evaluate the apparent activation energy related to the ionic transport in the VTF equation and several important parameters in the WLF equation.It is worthwhile to notice that a direct linear relationship between the ionic conductivity and free volume fraction is established using the WLF equation based on the free volume theory for nanocomposite electrolyte,which indicates that the segmental chain migration and ionic migration and diffusion could be explained by the free volume theory.     

Narrow pulse formation using nonlinear LC ladder networks

Soliton propagation in a nonlinear lossy LC ladder network has been studied. We propose a quadratic polynomial expression to model the C-V characteristic of the nonlinear capacitor of the LC ladder network. This fits the experimental C-V data better over a wider range of the applied voltage, compared with the conventionally used formulae.

Using this C-V expression, the Korteweg-de Vries (KdV) equation with a loss term has been obtained. This nonlinear equation has been solved by employing a novel technique that is based on Fourier series analysis. We have investigated the effects of bias voltage on the soliton pulse width and peak voltage and found a good agreement between the theoretical and experimental results.     

Temporal gas temperature of atmospheric pressure air plasma

In this paper, temporal gas temperature in plasma was measured by Rayleigh scattering in a passive way since synchronization was difficult due to the randomness of current pulses. The plasma was generated between a 10 mm pin-to-plane gap connected to a H.V DC voltage through a 130 MΩ resistor and a skin sample was placed on a grounded plate. Even the plasma can be touched by a human hand without any feeling of warmth, the peak temperature could be 337 K then decrease to 295 K over 60 μs at 1 mm. Moreover, the applied voltage dramatically affects peak current and the peak temperature. Therefore, the transient “high” temperature cannot be touched and the so-called “cold” plasma might not be “cold”.     

Minimum noise temperature of a practical SIS quantum mixer

Noise temperature of a SIS quantum mixer has been calculated as function of local oscillator voltage and signal source conductance on the basis of a measured I–V characteristic. Applying Tucker's quantum theory of mixing /1/, it is shown that the SIS mixer is quantum noise limited. Using cryogenic intermediate frequency amplifier, receiver noise temperature of 20 K seems to be possible at mm wavelength.     

基于Al2O3/Pt纳米晶/HfO2叠层的MOS电容存储效应研究

采用电子束蒸发Pt和后快速热退火的方法,研究了退火条件对Pt纳米晶的生长特性的影响,结果显示Pt纳米晶的密度随退火温度的升高和退火时间的延长均表现出先增大后减小的趋势.在800℃下退火20 s能得到分布均匀的、密度为30×10¹¹ cm^-2的Pt纳米晶.进一步研究了基于Al₂O₃/Pt纳米晶/HfO₂叠层的MOS电容结构的存储效应,表明其在-3—+8 V扫描电压范围下C-V< 关键词： Pt纳米晶 快速热退火 原子层淀积 存储效应     

Shear-Banding Evolution Dynamics during High Temperature Compression of Martensitic Ti-6Al-4V Alloy

The isothermal compression dynamics of ternary Ti-6 Al-4 V alloy with initial martensitic structures were investigated in the high temperature range 1083-1173 K and moderate strain rate regime 0.01-10 s^-1.Shear banding was found to still dominate the deformation mechanism of this process,despite its nonadiabatic feature.The constitutive equation was derived with the aid of Zener-Hollomon parameter,which predicted the apparent activation energy as 534.39 kJ/mol.A combination of higher ...     

Investigation of the free volume and ionic conducting mechanism of poly（ethylene oxide）-LiClO₄ polymeric electrolyte by positron annihilating lifetime spectroscopy

The positron annihilation lifetime and ionic conductivity are each measured as a function of organophilic rectorite(OREC) content and temperature in a range from 160 K to 300 K.According to the variation of ortho-positronium(o-Ps) lifetime with temperature,the glassy transition temperature is determined.The continuous maximum entropy lifetime(MELT) analysis clearly shows that the OREC and temperature have important effects on o-Ps lifetime and free volume distribution.The experimental results show that the temperature dependence of ionic conductivity obeys the Vogel-Tammann-Fulcher(VTF) and Williams-Landel-Ferry(WLF) equations,implying a free-volume transport mechanism.A linear least-squares procedure is used to evaluate the apparent activation energy related to the ionic transport in the VTF equation and several important parameters in the WLF equation.It is worthwhile to notice that a direct linear relationship between the ionic conductivity and free volume fraction is established using the WLF equation based on the free volume theory for nanocomposite electrolyte,which indicates that the segmental chain migration and ionic migration and diffusion could be explained by the free volume theory.     

Fabrication and electrical characterization of thermally deposited amorphous Se0.82In0.18 on n-Si (100)

Amorphous (a-) Se_0.82In_0.18 thin films have been deposited onto n-type silicon (n-Si) single crystal, using the three-temperature technique, in the fabricated configuration of Au/a-Se_0.82In_0.18/n-Si/Al. The current density-voltage (J–V) characteristics have been measured at different isotherms in the range of 198–313 K, thus inspecting the conduction mechanisms comparing with Au/a-Se/n-Si/Al heterojunctions. The analysis proved that the forward bias is characterized by two parts: current increasing exponentially with the applied voltage (low voltage bias region, V<0.2 V), and non-exponentially in the higher voltage region (V>0.2 V). At the low bias region, the current was dominated by a multi-tunneling capture-emission process with a rather temperature-independent effect in the temperature range investigated. However, at the high voltage region, the effect of temperature becomes more pronounced with an ohmic character in the range of 198 to 273 K. For temperatures higher than 273 K, and below the glass transition temperature of a-Se_0.82In_0.18 (T _g～330 K), the high voltage region could be subdivided into two parts: an ohmic conduction range that limited at bias voltage of 0.20 V<V<0.46 V, and a space charge limited current region for bias voltage of V>0.46 V. The reverse J–V characteristics showed a deviation from that of the ideal diode behavior, analogous to that of pure a-Se/n-Si heterojunctions.     

铝在氢氧化钠溶液中的电解加工与钝化机理

采用电解腐蚀装置,研究铝芯轴在1 mol/L的氢氧化钠溶液中4~28 V电压条件下的电流随时间的变化,得到电压与稳定时刻电流的关系曲线。通过改变电解液温度(20~35 ℃),对数据拟合后得到活化能。当电压高于28 V时,铝表面完全钝化,采用扫描电子显微镜得到未钝化样品和钝化样品的表面形貌,采用X射线衍射仪对未钝化样品和钝化样品进行分析表征,得出了钝化样品表面钝化层的主要成分为三羟铝石。从钝化产物的主要成分,推断出表面反应过程及钝化机理。