硅基中长波红外减反微结构研究

采用微加工工艺在Si衬底上制备了微柱和微锥阵列,结合光学建模分析,研究了结构参数对中长波（2.5~9 m）红外光反射率的影响规律。使用严格耦合波分析方法（RCWA）计算的微结构反射光衍射效率与傅里叶红外变换光谱仪（FTIR）测试的反射率结果吻合较好。研究结果表明,Si基微结构对TM及TE偏振光均有良好的红外光减反特性,微锥结构具有更好的减反效果,2.5~6.5 m中红外偏振光的反射率低至2%,同时表现出良好的宽谱与广角度减反特性。     

Silicon carbide and graphene based UV-IR dual-color detector

An ultraviolet-infrared dual-color detector is proposed and realized based on the vertical integration of single-layer graphene and a 4H-SiC layer by semiconductor micro-fabrication technology. The spectral response characteristics of the detector are analyzed. The ultraviolet response range is 208—356 nm with a responsivity larger than 0.4 mA/W and the infrared response range is 1.016—1.17 μm with a responsivity larger than 0.4 mA/W at room temperature and 5 V bias voltage. The peak responsivity of the graphene in the ultraviolet-C band at 232 nm is 0.73 mA/W and in the near infrared band at 1.148 μm is 0.64 mA/W. The peak responsivity of SiC layer in the ultraviolet-B band at 312 nm is 2.27 mA/W. Besides, the responsivity increases with the bias voltage.     

Electrocatalytic MOF-Carbon Bridged Network Accelerates Li+-Solvents Desolvation for High Li+ Diffusion toward Rapid Sulfur Redox Kinetics

Lithium-sulfur batteries are famous for high energy density but prevented by shuttling effect and sluggish electrochemical conversion kinetics due to the high energy barriers of Li⁺ transport across the electrode/electrolyte interface. Herein, the Li⁺-solvents dissociation kinetics is catalyzed and stimulated by designing a carbon bridged metal-organic framework (MOF@CC), aimed at realizing increased bare Li⁺ transport for the rapid conversion kinetics of sulfur species. Theoretical simulations and spectroscopic results demonstrate that the bridged MOF@CC well grants a special transport channel for accelerating Li⁺ benefited from aggregated anion/cation clusters. Moreover, the C N bridge between -NH₂ ligand in MOF and carbon shell enhances electron exchange, and thus promotes polysulfide catalytic efficiency and hinder polysulfide aggregation and accumulation. With the MOF@CC-modified separators, the assembled Li/S batteries deliver a reversible capability of 1063 mAh g^-1 at 0.5 C, a capacity retention of 88% after 100 cycles, and a high-rate performance of 765 mAh g⁻¹ at 5 C. Moreover, the large areal pouch cell with 100 µm Li foil and lean electrolyte is capable of stabilizing 855 mAh g⁻¹ after 70 cycles. These results well demonstrate the efficiency of catalyzing desolvation for fast Li+ transport kinetics and the conversion of polysulfides.     

Biomimetic Natural Biopolymer-Based Wet-Tissue Adhesive for Tough Adhesion,Seamless Sealed,Emergency/Nonpressing Hemostasis,and Promoted Wound Healing

Bioadhesives have been used in clinics among the most prospective alternatives to sutures and staples for wound sealing and repairing; however, they generally have inadequate adhesion to wet surfaces, improper mechanical strength, poor hemostasis, and cytotoxicity. To address these challenges, a robust wet tissue adhesive based on collagen and starch materials (CoSt) is designed in this study. CoSt hydrogels integrate the feature of drainage, molecular penetration and strengthen cross-linking similar to mussel, ivy, and oyster glues, which remove interfacial water quickly, reinforce tough dissipation and involve multiple reversible dynamic interactions. Therefore, they form strong adhesion and sutureless sealing of injured tissues, accompanying actuate robust biointerfaces in direct contact with tissue liquids or blood, resolving the crucial impediments with sutures and commercially accessible adhesives. The novel bioadhesive shows repeatable strong wet tissue adhesiveness (62 ± 4.8 KPa), high sealing performance (153.2 ± 35.1 mmHg), fast self-healing ability, excellent injectability, and shape adaptability. For different hemostatic needs in rat models of tail amputation, skin incision, severe liver, abdominal aorta, and transected nerve injuries, the CoSt hydrogel shows better hemostatic efficiency than fibrin glue because of the coordinate efficacy of tough wound sealing property, outstanding red blood cell arresting capability, and the activation of hemostatic barrier membrane. Moreover, in vivo investigation of the skin injury repair of the rat model validate that CoSt hydrogels accelerate wound healing and functional recovery via skin damage/defects. Tough wet adhesion, quick hemostasis, distinguished biocompatibility, suitability to match irregular-shaped target sites, and good wound healing promotion of the CoSt hydrogel makes it a prospective bioadhesive for various biomedical applications.     

半导体碳纳米管的长度分选及其薄膜晶体管性能研究

半导体型碳纳米管薄膜的高质量制备及其优化对于碳纳米管基电子器件具有重要意义.其中半导体型碳纳米管的长度是影响薄膜质量的重要因素之一.文章通过聚[9-(1-辛酰基)-9H-咔唑-2,7-二基](PCz)成功制备了高纯度半导体型碳纳米管溶液,经过循环沉积工艺,高效地降低了分散液中的短碳管含量,有效地提升了半导体型碳纳米管的平均长度,在此基础上通过标准工艺成功制备了高性能碳纳米管薄膜晶体管.结果显示,优化后的长碳纳米管溶液制备的薄膜晶体管具有优异的电学性能,其开关比高达107,迁移率高达34 cm2·V-1·s-1,比相应的短管性能提升了 3倍.     

Growth,doping and characterization of epitaxial thin films and patterned structures of AlN,GaN, and AlxGa1−xN

Advancements in the doping of GaN and Al_xGa_1−xN thin films, and the growth of GaN and Al_xGa_1−xN structures on patterned heterostructure substrates via metalorganic vapor phase epitaxy are reported. The acceptor-type behavior of Mg-doped GaN films grown in N₂ diluents is presented. Net ionized impurity concentrations up to 8×10¹⁸ cm⁻³ and Hall mobilities up to ≈14 cm² V⁻¹ s⁻¹ were measured for Mg-doped films grown in N₂ in the as-grown condition. Donor and acceptor doping of Al_xGa_1−xN alloys was performed. Acceptor doping of Al_xGa_1−xN for x≤0.13 and donor doping for x≤0.58 were achieved for films deposited at 1100 °C. Lateral epitaxial overgrowth of GaN and Al_xGa_1−xN layers was investigated. The growth and coalescence of GaN and Al_xGa_1−xN stripes patterned in SiO₂ and/or SiN_x masks deposited on GaN, including aligned second lateral epitaxial overgrowth on initial laterally overgrown GaN layers, are discussed.     

Mechanical property improvement and microstructure observation of SiCw–AlN composites

SiCw–AlN composites were produced with different sintering additives. Eight wt% Y₂O₃ was found a suitable sintering additive for mechanical property improvement of SiCw-AlN composites. With the sintering additive, SiCw–AlN composites with whisker content ranging from 10–30 wt% were hot-pressed to high density, and the flexural strength and fracture toughness were significantly improved with the increase of SiC whisker content. SEM and TEM observation indicated that several kinds of toughening mechanism contributed to the increasing toughness, including crack deflection, crack branching and whisker bridging process. The interfacial boundaries of the composites were also discussed in detail. ©     

基于圆形感兴趣区域多路视频实时拼接

针对视频拼接过程中面临的许多挑战,如实时性、有动态物体产生鬼影现象等,提出了一种基于圆形感兴趣区域（ROI）图像配准结合简化处理及图形处理器（GPU）加速的方法。首先,仅在ROI内提取特征点,提高了特征检测效率和匹配准确率。其次,为进一步降低时间开销,满足视频处理实时性需求,采用了两种策略：一方面,通过简化处理仅对首帧作图像配准,后续帧利用得到的单应性矩阵进行图像融合;另一方面,利用GPU多核实现并行化硬件加速。此外,当视场中有动态物体时,采用图形分割和多频带图像融合算法,有效地消除了鬼影。实验对两路640×480的视频进行拼接,该方法的处理速度可达27.8帧/秒。相对于基于加速鲁棒特征（SURF）算法的视频拼接方法,效率提高了26.27倍;相对于基于带方向的加速分段测试特征提取结合旋转的二进制鲁棒独立元素特征描述（ORB）算法的视频拼接方法,效率提高了11.57倍。实验结果表明,该方法可将多路视频实时地拼接为高质量的大场景视频。