微桥结构PZT厚膜红外探测器研究

利用KOH溶液腐蚀结合SF6气体干法刻蚀工艺制备了锆钛酸铅(PbZr0.3Ti0.7O3,PZT)厚膜热释电红外探测器,得到了器件Si基背面完全悬空的微桥绝热结构.使用由斩波器调制的黑体辐射,测试了探测器在低频段的电压响应率、噪声等效功率和探测率等参数.结果表明,探测器在调制频率为5.3 Hz时的电压响应率约为4.5×...     

BST/LSCO异质结构的研究

利用脉冲激光沉积法在STO(001)基片上外延生长了La0.5Sr0.5CoO3(LSCO)导电氧化物薄膜,研究了基片温度对LSCO薄膜结构和电性能的影响,并制备了Ni-Cr/BST/LSCO多层膜结构。XRD谱发现,沉积温度在450~700℃均能得到高度(00 l)取向的LSCO薄膜,LSCO(002)峰的半高峰宽FWHM=0.1°~0.2°;在LSCO薄膜上制备的BST介质膜具有良好的c轴取向和较高的表面平整度,其εr约为470,tgδ为0.036~0.060。     

布雷顿-逆布雷顿联合循环最优性能

用有限时间热力学研究布雷顿-逆布雷顿联合循环的热力学性能.调整质量流率和底循环压气机的入口压力优化该联合循环的功率和效率.分析表明,分别存在最佳的燃料流率和底循环压气机的最佳入口压力使循环输出功率最大,最大功率对应顶循环压气机压比有附加的最大值.给定质量流率和动力装置尺寸的情况下,通过合理分配顶循环压气机入口和底循环透平出口之间的流通面积,循环输山功率和热效率可以得到再次优化.     

射频溅射制备的BST薄膜介电击穿研究

采用射频溅射制备BST薄膜，研究了薄膜的介电击穿特性.实验表明，在电压增大到传统击穿电压(电流密度出现瞬时增大时的电压)之前，薄膜性能已被破坏，发现在传统击穿状态之前存在另一个新状态——初始击穿状态.通过测试各状态的J-V(电流密度-电压)、J-T(电流密度-温度)特性分析其导电机理，建立了薄膜结构、漏电性能随电场强度增大而变化的模型.最后提出了确定实际意义上击穿电压的方法. 关键词： BST薄膜 介电击穿 漏电流     

微波处理技术在材料科学工程中的应用

本文介绍了微波处理技术在材料科学与工程中的应用及原理，以及微波 技术的特点和优势，并指出了应用中的技术难点。     

ZnO基紫外探测器研究进展

近年来,直接带隙宽禁带半导体ZnO（3.37 eV）以其优越的光电特性而成为紫外探测领域研究中的新热点.文章介绍了不同类型的ZnO基紫外光敏探测器的结构和性能,并对ZnO基紫外光敏探测器的最新研究进展和应用前景进行探讨和展望.     

磁致伸缩薄膜力学行为的有限元仿真研究

建立了一种磁致伸缩薄膜力学行为的有限元计算方法.该方法将磁致伸缩薄膜在磁场中的形变行为等效为薄膜在热场中的各向异性热膨胀形变行为,基于该等效模型,利用有限元软件计算了磁致伸缩薄膜悬臂梁的力学行为与外加磁场的关系.结果表明,该方法可有效模拟磁致伸缩薄膜在外磁场下的力学行为.     

Low platinum loading PtNPs/graphene composite catalyst with high electrocatalytic activity for dye-sensitized solar cells

Platinum nanoparticles(PtNPs)/graphene composite materials are synthesized by a controlled chemical reduction of H2PtCl6 on graphene sheets.The electrocatalytic activity of a PtNPs/graphene composite counter electrode for a dye-sensitized solar cell(DSSC) is investigated.The results demonstrate that the PtNPs/graphene composite has high electrocatalytic activity for the dye-sensitized solar cell.The cell employing PtNPs(1.6 wt%)/graphene counter electrode reaches an conversion efficiency(η)of 3.89% upon the excitation of 100 mW/cm2 AM 1.5 white light,which is comparable to that of the cell with a Pt-film counter electrode(η=3.76%).It suggests that one can use only 14% Pt content of the conventional Pt-film counter electrode to obtain a comparable conversion efficiency.It may be possible to obtain a high performance DSSC using the PtNPs/graphene composite with a very low Pt content as a counter electrode due to its simplicity,low cost,and large scalability.     

Sodium beta-alumina thin films as gate dielectrics for A1GaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

<正>Sodium beta-alumina（SBA） is deposited on AlGaN/GaN by using a co-deposition process with sodium and Al₂O₃ as the precursors.The X-ray diffraction（XRD） spectrum reveals that the deposited thin film is amorphous.The binding energy and composition of the deposited thin film,obtained from the X-ray photoelectron spectroscopy（XPS） measurement,are consistent with those of SBA.The dielectric constant of the SBA thin film is about 50.Each of the capacitance-voltage characteristics obtained at five different frequencies shows a high-quality interface between SBA and AlGaN.The interface trap density of metal-insulator-semiconductor high-electron-mobility transistor（MISHEMT） is measured to be（3.5～9.5）×10¹⁰ cm^-2·eV^-1 by the conductance method.The fixed charge density of SBA dielectric is on the order of 2.7×10¹² cm^-2.Compared with the AlGaN/GaN metal-semiconductor heterostructure high-electronmobility transistor（MESHEMT）,the AlGaN/GaN MISHEMT usually has a threshold voltage that shifts negatively. However,the threshold voltage of the AlGaN/GaN MISHEMT using SBA as the gate dielectric shifts positively from—5.5 V to—3.5 V.From XPS results,the surface valence-band maximum（VBM-E_F） of AlGaN is found to decrease from 2.56 eV to 2.25 eV after the SBA thin film deposition.The possible reasons why the threshold voltage of AlGaN/GaN MISHEMT with the SBA gate dielectric shifts positively are the influence of SBA on surface valence-band maximum （VBM-E_F）,the reduction of interface traps and the effects of sodium ions,and/or the fixed charges in SBA on the two-dimensional electron gas（2DEG）.     

基于钛酸锶钡介电非线性效应的可调谐太赫兹人工电磁媒质

数值仿真研究了内嵌钛酸锶钡薄膜夹层的金属网格谐振单元人工电磁媒质的谐振行为. 垂直电磁波激励下, 电磁响应频率随着内嵌夹层钛酸锶钡薄膜介电常数的变大呈现红移, 调谐率为22.6%. 本文提出的人工电磁媒质调谐方法只需要以结构单元的上下两层金属图形本身作为电极对内嵌夹层钛酸锶钡薄膜施加电压, 极大地简化了可调谐人工电磁媒质的制备及应用, 在太赫兹人工电磁媒质调制器等方面具有潜在的应用. 关键词： 人工电磁媒质 钛酸锶钡薄膜 介电非线性 调谐