固态微波功率器件测量夹具及其校准技术研究

固态微波功率器件由于其封装形式的特殊性,测量过程中必须引入测量夹具作为桥梁,才能完成接口形式的转换,进而开展测试工作。针对固态微波功率器件微波电参数在测试中,测量夹具给测量结果带来影响的问题,对固态微波功率器件测量夹具及其校准技术进行了研究。文章介绍了采用TRL校准方法,并利用矢量网络分析仪的误差修正功能来去除测量夹具误差,从而得到被测器件的真实性能参数。通过具体试验数据表明,对测量夹具的校准和误差的去除是可行有效的,从而可以在测量结果中去除测量夹具的影响而得到被测器件的"净"参数。     

Ag纳米颗粒等离激元光散射增强对Si刻蚀形貌的影响机制

通过实验与有限元(FDTD)模拟系统研究了不同粒径尺寸的Ag纳米颗粒在P(100)Si表面刻蚀过程中等离激元光散射增强对刻蚀孔形貌的影响。SEM结果表明,刻蚀孔由与粒径尺寸接近的垂直孔演化为一种上大下小的火炬状形貌特征孔,该孔的直径与纳米颗粒尺寸散射半径相仿。模拟不同粒径的Ag纳米颗粒进入刻蚀孔后的光散射特征,证实了Ag纳米颗粒等离激元散射对刻蚀孔初期形成的重要作用。分析表明,基于光照条件下电子-空穴的激发特征,刻蚀孔的形貌主要依赖Ag纳米颗粒等离激元散射的光增强,即通过改变入射光频率以及Ag纳米颗粒粒径可以有效地调控Si表面形貌特征。Ag纳米颗粒等离激元光散射增强技术在Si基太阳能电池、发光二极管(LED)器件等领域有潜在应用前景。     

墨水直写、喷墨打印和激光直写技术及其在微电子器件中的应用

直写技术是一种新型微加工技术,其加工过程不需模板并可在亚微米至厘米范围实现材料加工成型.墨水直写、喷墨打印和激光直写作为最常用的直写技术,具有强大的二维、三维成型能力和优异的成型精度,可实现金属、陶瓷、聚合物、水凝胶等复杂构型的程序化构筑,被广泛应用于微电子、组织工程、微流控等领域.阐述了这3种直写技术的构型原理和材料选择,重点介绍了其在微电子器件制造中的应用,讨论了当前研究的难点和热点问题,并对其未来发展趋势进行了展望.     

Routes for high-performance thermoelectric materials

Thermoelectric materials can be used in direct conversion of heat to electricity and vice versa. The past decade has witnessed the rapid growth of thermoelectric research, targeting high thermoelectric performance either via reduction in the lattice thermal conductivity or via enhancement of the power factor. In this review, we firstly summarize the recent advances in bulk thermoelectric materials with reduced lattice thermal conductivity by nano-microstructure control and also newly discovered materials with intrinsically low lattice thermal conductivity. We then discuss ways to enhance the electron transport abilities for achieving higher power factor by both novel and traditional methods. Finally, we highlight the recent development in single-crystal thermoelectric materials. These strategies are successful in synergistically manipulating the thermal conductivity and electron transport properties, which have significantly advanced thermoelectric performance on materials. For device applications on these high-performance materials, new opportunities may arise though stability, electrode contacts, mechanical properties, and other problems need to be solved in the near future.     

Gas formation and biological effects of biodegradable magnesium in a preclinical and clinical observation

Magnesium alloys are biodegradable metals receiving increasing attention, but the clinical applications of these materials are delayed by concerns over the rapid corrosion rate and gas formation. Unlike corrosion, which weakens mechanical properties, the gas formation issue has received little attention. Therefore, we evaluated the gas formation and biological effects for Mg implants through preclinical (immersed in Earle’s balanced salt solution and in vivo) and clinical studies. The immersion test examined the gas volume and composition. The in vivo study also examined gas volume and histological analysis. The clinical study examined the gas volume and safety after Mg screw metatarsal fixation. Gas was mainly composed of H₂, CO and CO₂. Maximum volumes of gas formed after 5 days for in vivo and 7 days in clinical study. Within the clinical examination, two superficial wound complications healed with local wound care. Osteolytic lesions in the surrounding metaphysis of the Mg screw insertion developed in all cases and union occurred at 3 months. Mg implants released gas with variable volumes and composition (H₂, CO, and CO₂), with no long-term toxic effects on the surrounding tissue. The implants enabled bone healing, although complications of wound breakdown and osteolytic lesions developed.     

Nanoscale Lacing by Electrons

The ability to harness the optical or electrical properties of nanoscale particles depends on their assembly in terms of size and spatial characteristics which remains challenging due to lack of size focusing. Electrons provide a clean and focusing agent to initiate the assembly of nanoclusters or nanoparticles. Here an intriguing route is demonstrated to lace gold nanoclusters and nanoparticles in string assembly through electron‐initiated nucleation and aggregative growth of Au(I)‐thiolate motifs on a thin film substrate. This size‐focused assembly is demonstrated by controlling the electron dose under transmission electron microscopic imaging conditions. The Au(I)‐thiolate motifs, in combination with the molecularly mediated alignment, facilitate the interstring electrostatic and intrastring aurophilic interactions, which functions as a molecular template to aid electron‐initiated 1D lacing. The findings demonstrate a hierarchical route for the 1D assemblies with size and spatial tunable catalytic, optical, sensing, and diagnostic properties.     

Pseudocapacitive Sodium Storage by Ferroelectric Sn2P2S6 with Layered Nanostructure

Sodium ion batteries (SIB) are considered promising alternative candidates for lithium ion batteries (LIB) because of the wide availability and low cost of sodium, therefore the development of alternative sodium storage materials with comparable performance to LIB is urgently desired. The sodium ions with larger sizes resist intercalation or alloying because of slow reaction kinetics. Most pseudocapacitive sodium storage materials are based on subtle nanomaterial engineering, which is difficult for large‐scale production. Here, ferroelectric Sn₂P₂S₆ with layered nanostructure is developed as sodium ion storage material. The ferroelectricity‐enhanced pseudocapacitance of sodium ion in the interlayer spacing makes the electrochemical reaction easier and faster, endowing the Sn₂P₂S₆ electrode with excellent rate capability and cycle stability. Furthermore, the facile solid state reaction synthesis and common electrode fabrication make the Sn₂P₂S₆ that becomes a promising anode material of SIB.