隧穿结对具有中间层的非晶硅/微晶硅叠层电池的影响

为了改善非晶硅/微晶硅叠层电池的载流子输运效果,将隧穿结引入到具有中间层结构的叠层电池中,研究了隧穿结的结构、掺杂浓度、厚度等条件对叠层电池性能的影响.实验结果表明,叠层电池中引入隧穿结构成“隧穿结-中间层”结构,可以进一步改善电池性能,经过结构和参数优化的隧穿结可以提高子电池的电流密度匹配度,提升叠层电池转换效率.加...     

基于共振光隧穿效应的角加速度传感器设计

阐述了一种基于共振光隧穿效应的角加速度传感器的设计方法,分析了其传感特性,并以共振光隧穿理论为基础,利用Mathematica软件进行了仿真分析。该加速度传感器的品质因数可以达到1.96×10⁸,远高于经典F-P腔的品质因数8.183×104。灵敏度可以达到0.1°/nm,     

微机械隧道陀螺仪的设计

提出了一种高精度低量程复合梁结构的新型隧道电流式陀螺仪,采用标准硅微加工技术进行了设计与加工,实现了隧道效应传感器的高灵敏度与哥氏力测量角速度原理的结合,从力学角度对陀螺仪的驱动梁与检测梁的力学特性进行了分析,对陀螺的基本原理进行了必要的模态和静力学仿真,仿真结果满足驱动与检测模态的要求。另外,制定了切实可行的工艺流程,阐述了加工所需要的关键工艺,重点研究了隧尖制造技术。     

多晶硅/氧化硅/多晶硅非平面结构中Fowler-Nordheim隧穿及氧化层退化研究(英文)

Fowler-Nordheim隧穿被广泛应用于EEPROM和闪存中的擦除操作。多晶硅到多晶硅的F-N隧穿具有较高的隧穿效率。本论文基于分栅闪存存储器的结构,对于多晶硅/隧穿氧化层/多晶硅非平面结构的F-N隧穿及其引起的氧化层退化进行了研究。相比于平面结构,非平面结构显示出更高的F-N隧穿效率,且隧穿效率还可通过降低氧化层厚度或者增加预热氧化处理的方法进一步提高。较低的F-N隧穿电流密度显示出较慢的隧穿氧化层退化速率。降低氧化层厚度或者增加热氧化处理也可减缓隧穿氧化层的退化。另外,论文还讨论了研究结果对于改善分栅闪存擦除特性以及耐久性的意义。     

隧穿型量子效应薄膜材料制备技术

探讨了隧穿型量子效应薄膜材料制备技术,并应用分子束外延方法制备了典型结构外延材料GaAs基共振隧穿二极管,经过器件验证,得到了较好的结果.重点讨论了关键制备技术,包括束流精细控制和间歇式生长方式,主要是为了生长出更接近完美的晶体结构和晶体表面,并分析了测试结果和器件验证结果,最终得出整套隧穿型量子效应薄膜材料制备技术.     

基于隧穿磁阻效应的非侵入式高灵敏度电流传感器研究

隧穿磁阻器件是新一代磁半导体传感器,其具有高灵敏度、可实现交直流混合测量的特点。该研究介绍一种基于隧穿磁阻器件的高灵敏度非侵入式表贴电流传感器设计方法。该传感器可非侵入式安装在铜排表面实现毫安级微弱电流的测量。计算毫安级电流在铜排表面产生的感应磁场大小并提出了隧穿磁阻器件的参数选型依据。进一步设计信号调理电路并提出利用分段拟合算法弥补高灵敏度隧穿磁阻器件线性范围较小的缺陷。最后,搭建测试验证平台验证传感器设计方法。结果表明,所设计的传感器可覆盖毫安至1A的测量范围,在百毫安范围内,绝对误差小于1mA,在百毫安至1A范围内,传感器的相对误差小于2%。     

发射极δ掺杂的InGaAs/InPDHBT的特性分析

设计了一种新结构的InGaAs/InP双异质结晶体管(DHBT),其中发射结采用δ掺杂和阻挡层结构,集电极采用N+掺杂复合结结构.考虑隧穿作用和发射结空间电荷区复合电流的影响,计算了δ掺杂浓度和N+、n-层厚度等参数变化对InGaAs/InP DHBT电流、I-V输出特性、电流增益的影响,计算结果表明,随着这些参数值增大,InGaAs/InP DHBT输出特性逐渐改善.当δ掺杂浓度大于2×1012cm-3时,电流增益趋于饱和.     

基于GaAs/AlAs腐蚀自停止的新型水听器工艺

针对感应耦合等离子（ICP）刻蚀气室气体分布不均匀性所导致的被刻蚀台面中间厚、边缘薄及干法刻蚀后残余应力大等缺点,进行了GaAs／AlAs的选择性湿法腐蚀工艺研究．腐蚀液为50％一水柠檬酸（C6H8O7·H2O）溶液与30％双氧水（H2O2）的混合物,当二者体积比为3：1时,GaAs／AlAs的选择比达到79以上．用原子力显微镜（AFM）和扫描电镜（SEM）对腐蚀后的试验片测试后发现,该体积比腐蚀液腐蚀的试验片具有表面粗糙度低、刻蚀各向异性好、选择比高等优点,能够满足传感器加工的需要;结合试验结果,设计了一种待加工梁厚3μm的外延材料结构,并对传感器的加工工艺进行了优化;最后,采用ANSYS对所设计的结构进行了仿真分析,仿真结果表明,该结构具有可行性,可实现水平面内的声学探测．     

界面自旋翻转对有限尺寸的铁磁体/非磁性半导体/铁磁体体系自旋注入的影响(英文)

本文考虑了界面自旋翻转效应后对有限尺寸的铁磁体/非磁性半导体/铁磁体异质结中的自旋注入问题进行了系统的理论探讨.由于自旋在两种介质界面上发生的翻转散射,自旋极化流的每一个分量在界面上都不可能连续.计算结果表明,当自旋注入效率从0增加到100%的过程中,铁磁体/非磁性半导体/铁磁体异质结的隧穿磁阻增大了两个数量级.这一事实证明界面的自旋翻转效应直接影响着铁磁体/非磁性半导体/铁磁体异质结的隧穿磁阻.     

各向异性磁电阻传感器高精度测试技术

针对各向异性磁电阻(AMR)传感器在受到强磁干扰后灵敏度下降问题和温漂问题,提出运用"复位/置位"脉冲对传感器进行高精度测量的技术.分析了各向异性磁电阻传感器工作原理和复位/置位结构;阐述了复位/置位测试方案和零点补偿方法;设计了相应的电路,并进行了一系列的实验验证.实验结果表明:采用基于"复位/置位"脉冲的AMR磁传感器高精度测试技术可以有效解决磁阻传感器受强磁干扰后灵敏度下降问题,并有效消除AMR传感器零点温度漂移影响,提高了传感器的测量精度.在高精度磁场测量领域具有参考意义.     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.