Investigation of optical properties of core–shell silicon nanowires

The ability to control the size, orientation, composition and morphology of silicon nanowires (SiNWs) presents an ideal platform for exploring a wide range of potential technological applications. In this work, we demonstrated the detail study of optical properties of highly disordered core–shell SiNWs that were grown by atmospheric pressure chemical vapor deposition. The microstructure of SiNWs was characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The TEM study shows that the SiNWs consists of crystalline core silicon surrounded by thick amorphous silicon oxide. The total diameter including the outer SiO₂ sheath was 60–80 nm. The reflection and absorption of a-SiO₂/c-SiNWs were affected by process parameter like silane flow rate and hydrogen dilution. The optical reflection of SiNWs decreased with increasing photon energy across the visible and near the ultraviolet range, approaching moth's eye antireflection. Specifically, a minimum reflection of 2–3% was observed at 400 nm. The band gap is estimated at ∼1.32 eV by quasi-direct band Tauc's plot. The sum of localized states at the band edge is ∼0.53 eV. Straight SiNWs have lower reflection than those of nanoparticles mixed SiNWs and coil mixed SiNWs. The reflection and absorption of SiO₂/SiNWs were confirmed to respond strongly to infrared with increasing H₂ flow rate.     

基于RDM的动目标检测成像工程实现可行性研究

本文提出了基于RDM算法的动目标检测成像的工程实现方案的原理图,通过对该算法的计算量的估计,证实了该算法用于LSAR实时动目标检测的可行性。     

薄膜膜系计算的计算机程序设计

根据膜堆的特征矩阵,求出单层膜的光学导纳,在单层膜的基础上,进行层层递推,叠加起来,求出膜块的等交内,计算振幅反射系数,最后求出整个膜系的反射率、透射率。     

密斯·凡·德·罗似是而非的对称

通过对有关巴塞罗那馆的照片、文字、图纸的深入分析以及在重建的展馆的现场观察,罗宾·埃文斯探讨了密斯·凡·德·罗的这一重要作品中所暗藏的种种似是而非的属性：对称性与不对称性,结构的逻辑与外表的逻辑,延展的空间与封闭的空间,对体量的压抑与对光线的操纵,打破秩序的反射与创造统一性的反射,等等,并且对巴塞罗那馆的政治性进行了重新的解读——它的美使密斯和他的同代人从政治与暴虐中分神。     

The effect of B site cations on optical properties of paraelectric KTa1/2Nb1/2O3 crystal

The effect of B site cations on the optical properties of paraelectric solid solution KTa_1/2Nb_1/2O₃ crystal has been studied by means of density functional theory. Three arrangements of B site cations are presented. The optimized lattice parameters are in good agreement with the experimental values. Reflectivity, refractive index and optical conductivity are investigated. The calculated optical properties are very close to the results of other researchers. It is found that the B site cations ordering obviously influences the optical properties of KTN crystal.     

微纳结构形式对镍薄膜超快热化动力学的影响

制备了厚、薄、反点阵结构以及颗粒结构镍薄膜分别作为体、面、线和点结构薄膜样品,利用飞秒激光泵浦探测技术,检测了4种镍薄膜的瞬态反射率变化情况,研究了微纳结构形式对镍薄膜超快热化动力学的影响。结果表明对于微纳结构镍薄膜来说,随着结构维数的减小,量子限域效应对电子热化时间有延缓作用。     

Correlation between reflectivity and photoluminescent properties of porous silicon films

Porous silicon (PS) layers were formed on p-type, 〈1 0 0〉 oriented, 1-5 Ω cm resistivity Cz silicon wafers by electrochemical etching in an HF:C₂H₅OH (1:2 by volume) electrolyte at room temperature at a constant current density 20 mA/cm². The etching duration was varied to achieve PS layers of different morphologies and thicknesses. Both the photoluminescence (PL) and the total diffused reflectivity spectra of the PS layers were measured. It was found that for the PS layers grown for etching durations of less than 90 s the PL emission is insignificant and reflectivity is quite low. Such PS layers can be used as antireflection coatings (ARC) on solar cells. The PS layers formed for etching durations greater than 90 s show a significant PL emission in 500-800 nm range with peak lying in 630-660 nm wavelength range. When etching duration increases from 90 s to 8 min the PL intensity increases and the PL peak shows a blue shift. With further increase in etching duration the PL intensity decreases and PL peak shows a red shift. The reflectivity of the photoluminescent layers increases with etching duration showing a highest value for a sample grown for 8 min. Further increase in etching duration up to 20 min the reflectivity decreases and then increases. Striking observation is that both the PL emission intensity and reflectivity in the wavelength range of 550-800 nm are maximum for the PS layer grown for the etching duration of 8 min.     

横向变速小尺度体反射系数变化规律研究

AVO技术的研究已有30多年的发展历程,其中有起有落。近年来AVO技术的应用日趋广泛,发展较快。在寻找非均质油气藏方面,AVO技术具有其他方法不可替代的作用。通过对横向小尺度体的模型设计,正演模拟的计算及与Zoeppriz方程计算理论值的对比,讨论了横向小尺度体大小变化、速度变化对反射系数的影响,得出了横向尺度大小及速度变化对反射系数的影响规律,总结了横向变速时反射系数随偏移距的变化规律。     

A method for AlCu interconnect electromigration performance predicting and monitoring

The physical properties of (bottom)Si/SiO₂/Ti(top) and (bottom)Si/SiO₂/Ti/TiN/Al(0.5 wt.% Cu)(top) structures by different processes were compared and studied. The resistivities of thin Ti films and the reflectivities of thin Al alloy films were found to correlate to their microstructure as well as the mean time to fail (MTTF) in electromigration (EM) testing. A method to predict and monitor the EM performance of the AlCu interconnects was proposed.     

直流反应磁控溅射法制备氮化钛薄膜

研究了采用直流反应磁控溅射法制备TiN薄膜的工艺条件。研究发现：在保持其它工艺参数不变的条件下,溅射的TiN薄膜在不同温度区域存在的物相不同,薄膜的主要成分是多晶立方相TiN,240℃附近是薄膜择优取向由（111）向（200）转变的临界点。随着基底温度升高,薄膜表面粗糙度先变小后变大,沉积最佳基底温度值是330℃,该温度下薄膜的粗糙度最小,膜层致密均匀,没有大尺寸缺陷且光洁度好。