Chalcogenide Phase Change Material for Active Terahertz Photonics

The strikingly contrasting optical properties of various phases of chalcogenide phase change materials (PCM) has recently led to the development of novel photonic devices such as all‐optical non‐von Neumann memory, nanopixel displays, color rendering, and reconfigurable nanoplasmonics. However, the exploration of chalcogenide photonics is currently limited to optical and infrared frequencies. Here, a phase change material integrated terahertz metamaterial for multilevel nonvolatile resonance switching with spatial and temporal selectivity is demonstrated. By controlling the crystalline proportion of the PCM film, multilevel, non‐volatile, terahertz resonance switching states with long retention time at zero hold power are realized. Spatially selective reconfiguration at sub‐metamaterial scale is shown by delivering electrical stimulus locally through designer interconnect architecture. The PCM metamaterial also features ultrafast optical modulation of terahertz resonances with tunable switching speed based on the crystalline order of the PCM film. The multilevel nonvolatile, spatially selective, and temporally tunable PCM metamaterial will provide a pathway toward development of novel and disruptive terahertz technologies including spatio‐temporal terahertz modulators for high speed wireless communication, neuromorphic photonics, and machine‐learning metamaterials.     

基于非晶锗热电阻的柔性MEMS流速传感器的设计与仿真

针对铂等常用金属热敏材料电阻温度系数(TCR)不高,导致热式MEMS流速传感器宽量程测量时功耗高的问题,设计了 一种基于非晶锗(a-Ge)薄膜热电阻的低功耗、宽量程柔性MEMS流速传感器.非晶锗热电阻材料具有较高的TCR系数(约为-0.02/K)和室温电阻率(5Ω·m),传感器在较低的工作温差和功耗下可获得宽量程的流速测量.阐述了该柔性MEMS流速传感器的设计结构、工作原理、3D有限元建模和热-流场仿真结果.利用聚酰亚胺衬底空腔膜上的四个非晶锗热电阻同时作为自加热热源和测温元件.四个非晶锗热电阻组成一个惠斯通电桥,同时结合热损失和热温差原理来实现宽量程流速测量和测向.仿真结果表明,惠斯通电桥采用恒电流供电只需120μA,使得非晶锗热阻的工作温度与环境温度之间的温差不高于6 K,就可对0～50 m/s范围内的流速进行测量,且功耗在1.368 mW以内.该柔性流速传感器易于采用MEMS技术批量制造,可贴于曲面应用,非常适于物联网等低功耗流速传感领域.     

由硫酸锌废渣制备二氧化锗的研究

采用催化、酸浸、蒸馏等工艺，有效地回收了硫酸锌废渣中的锗，为锗的获取提供了一条经济、可行的途径。     

Glass–Crystal Transition in II-IV-V2 Semiconducting Compounds

The crystallization behavior of amorphous CdGe_xAs₂, where the x values were varied from 0 to 1.2, was studied in order to document the effect of germanium on the amorphous structure. The glass-forming tendency of amorphous CdGe_xAs₂ was evaluated by Hruby's criterion. The crystallization mechanism of each group was proposed, interpreting DSC, XRD, EDS, and TEM data, interactively. The crystallization behavior appeared as two distinct groups: those based on the CdAs₂ structure and those on the CdGeAs₂ structure (chalcopyrite), depending on Ge content. Ge atoms were found to suppress a glass-to-glass exothermic transformation to higher temperatures in the CdAs₂ group, and crystallization in both groups. Proposed models of amorphous structure from previous investigators, measuring the radial distribution function, magnetic susceptibility, and macroscopic density, were correlated to the crystallization studies herein. A model of the transformation of glass structure with increasing Ge content from a CdAs₂ to a CdGeAs₂-like structure was established by extrapolation of experimental results indicating this behavior in crystalline CdGe_xAs₂ compounds with varying x .     

小型准直式红外地球模拟器研究

地球模拟器是卫星姿态测量控制关键部件—摆动扫描式红外地球敏感器的一种重要地面模拟试验与精度标定仪器。本文针对卫星同步轨道高度(35786km),采用准直式方案,研制了一种口径为Φ150mm的准直式红外地球模拟器,它能提供17.46°的地球张角,实现了地面上模拟卫星在太空中所看到的地球。文中详细介绍了准直式红外地球模拟器的组成和总体结构,采用红外光学技术,设计了锗准直透镜,通过理论分析得出地球光阑、热地球位置和大小与地球张角、锗准直透镜光学参数之间的关系,为地球模拟器的研制提供了设计依据。地球张角是衡量地球模拟器精度的指标,通过实验对地球张角进行了测试,结果表明地球张角误差小于±0.05°。     

Selective sorption of a Ge(IV) oxoanion by composite sorbent with hydrous oxide of cerium

In this work, composite sorbent based on hydrous cerium oxide was used for selective removal of a Ge (IV) oxoanion. Experiments were carried out by batch equilibrium tests and dynamic column sorption. The best sorption capacity of the Ge(IV) anion was reached at a pH of 9, where the sorption capacity was about 1.1 g/L. The negative effect of chlorides and sulfates was not observed in the concentration range of 100–1000 mg/L. The optimal flow rate for Ge(VI) sorption by sorbent CeO₂/XAD-7 was determined to be 6–12 BV/h. For regeneration, 10 BV of 1 mol/L HCl solution was used.     

不同直径张应变锗材料对光谱和晶体质量的影响

绝缘体上张应变锗材料是通过能带工程提高锗材料光电性能得到的一种新型半导体材料,在微电子和光电子领域具有重要的应用前景.采用微电子技术中的图形加工方法以及利用锗浓缩的技术原理,在绝缘体上硅(SOI)材料上制备了绝缘体上张应变锗材料.喇曼与室温光致发光(PL)测试结果表明,不同圆形半径的绝缘体上锗材料张应变均为0.54％.对于绝缘体上张应变锗材料,应变使其发光红移的效果强于量子阱使其发生蓝移的效果,总体将使绝缘体上张应变锗材料的直接带发光峰位红移.同时0.54％张应变锗材料的直接带发光强度随着圆形半径的增大而减弱,这主要是因为圆形半径大的样品其晶体质量较差.该材料可进一步用于制备锗微电子和光电子器件.     

锗在湿法炼锌系统的分布及行为

文中指出了锗在湿法炼锌系统走向;说明了锗在湿法炼锌系统分布及行为;重点对浸出阶段最佳除锗条件、锗对电解工序的危害以及几种富集回收锗工艺做了叙述;强调了生产中应注意几点事项.     

（英）离子束溅射法制备碳化锗薄膜的红外光学特性和力学特性

采用离子束溅射法通过在CH4和Ar 的混合气体中溅射Ge靶材制备碳化锗(Ge1-xCx)薄膜.分别通过原子力显微镜、拉曼光谱和X射线光电子能谱、傅里叶变换红外光谱以及纳米压痕测试研究了薄膜的表面形貌、化学结构、光学特性和力学特性.同时分析了制备薄膜时的离子源束压和薄膜性质之间的关系.结果表明,薄膜的粗糙度随束压的增大而减小.在较高束压下制备的薄膜含有较少的C元素和较多的Ge-C键.薄膜具有非常好的红外光学特性和力学特性.薄膜在较大波长范围内具有良好的透光性能.C元素含量随着束压的升高而降低,进而导致薄膜的折射率在束压从300 V增大到800 V的过程中逐渐升高.薄膜的硬度大于8 GPa.由于薄膜中的Ge-C键代替了C-C 键和C-Hn键,薄膜的硬度随束压的增加逐渐增加.     

Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B₂O₃ encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters.