电离光电子的干涉效应与空间角分布

基于光电子角分布成像光谱技术的基本原理,讨论了单光子共振三光子电离方法获得的光电子成像图,同时也分析了光电子角分布的物理含义.着重研究了多通道电离过程中光电子的干涉作用对成像光谱的影响;分析了光电子空间角分布以及光电成像光谱与原子能态信息的关系.     

表面性质对扫描力显微术成像的影响

利用微接触印刷的方法制备了图形化的自组装膜,考察了膜的表面性质对接触式原子力显微镜（ＡＦＭ）,摩擦力显微镜（ＦＦＭ）和剪切力显微镜（ＳＦＭ）的成像的影响。发现ＡＦＭ能反映样品的表面形貌,而ＦＦＭ和ＳＦＭ的以表面性质的影响较大,在表面性质差别很大的图形表面上会出现图像衬底与表面形貌反转的现象。     

用于多光子显微术的飞秒近红外Cr：镁橄榄石激光器

日本大阪大学的科学家运用Cr：镁橄榄石激光器作为近红外激励源，研制出一种多光子显微镜，它在对不透明、脆弱的生物样品的成像方面非常有用。     

可逆饱和光转移过程的荧光超分辨显微术

基于可逆饱和光转移过程的荧光超分辨显微技术,从原理上打破了原有的光学远场衍射极限对光学系统极限分辨率的限制,在生物、化学、医学等多个学科拥有广泛的应用前景。回顾了近年来超分辨显微研究的历史,综述了目前常见的几种基于可逆饱和光转移过程的荧光超分辨显微方法,详细描述了各自的技术特点并对比了其优缺点,阐述了相关领域内最新的研究工作进展。     

化学镀层的扫描开尔文力显微术(SKFM)研究

首次在化学镀样品上成功地实现了扫描开尔文力显微镜的测量，得到了化学镀层表面形貌以及与微观组分分布相关的表面电势差信息。该分析方法没有复杂的样品制备过程，不会破坏样品的原始状态，对于宏观上具有确定组分的微观相分离样品，可以由表面电势差得到不同相的微区分布。比其它的常规分析手段有更高的空间分辨率，能获得更多的材料微区结构、组分与性能间关系的信息。     

微型化显微成像系统的关键技术及研究进展（特邀）

神经环路动态功能的解析是当前脑科学领域的重点和难点,微型化显微成像技术为其研究提供了重要手段。相较于双光子荧光成像和光纤光度法,微型化显微系统能够在模式动物自由活动状态下进行长时程、单细胞分辨率、实时成像。近十几年来,科学家们围绕可穿戴、高稳定性要求,先后研制了单光子、多光子成像系统,并从荧光探针、光电子元件、数据传输等方面进行不断优化,提升系统性能,扩展应用范围。将从成像原理、基本结构、系统优化、应用方案及未来发展方向等方面对微型化显微成像系统进行分析和讨论,综述各方向研究进展,旨在为该领域技术提升和神经科学应用提供参考。     

InP基光电子和微电子器件的应用潜力及开发现状

讨论了ＩｎＰ基光电子和微电子器件的应用潜力和开发现状，指出可靠性和价格问题是ＩｎＰ技术产业化的两个主要障碍。     

集成电路失效定位技术现状和发展趋势

集成电路(IC)失效分析包含了不同的分析流程,但所有的步骤都是以失效定位和故障隔离作为第一步工作。失效定位指的是不断地缩小半导体器件故障范围直至可以进行破坏性物理分析的过程。根据IC的结构特点和分析思路,将整个失效分析流程中失效定位分为封装级失效定位、器件级失效定位和物理分析失效定位。通过定位技术结合案例分析的形式,重点介绍了时域反射、X射线断层扫描、扫描声学分析、锁相红外成像、光发射分析、激光激发技术和电压衬度等关键的失效定位技术原理和方法。总结了不同失效定位技术的适用范围和面临的挑战。同时,也对未来失效分析技术发展趋势进行了展望。     

光子晶体光纤的原理、应用和制作

光子晶体光纤是一种新型光纤,它与传统光纤相比在结构和性能上有显著的差别和优势。简要分析了光子晶体光纤的原理,并介绍了其特性、应用、分析和制作方法。     

基于SEM电压衬度的缺陷定位方法研究

光发射显微分析、光致电阻变化技术两种电失效定位方法在精确定位缺陷上存在局限性,为此提出了基于SEM电压衬度的联用方法用于精确定位集成电路缺陷.首先根据电特性测试进行光发射显微分析或者光致电阻变化分析,结合电路原理和版图,提出失效区域的假设,再进行电压衬度像分析,通过衬度翻转可精确和快速确定缺陷位置,最后通过FIB或者T...     

Chemical-Mechanical polishing of parylene- n films: evaluation by X-Ray photoelectron spectroscopy and atomic force microscopy

The surface quality of parylene-N(PA-N) films, as determined by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), after chemical-mechanical polishing (CMP), is influenced mostly by two factors: quality of the as-deposited film and the slurry composition. The higher the quality of the as-deposited film (more specifically, less oxygen content), the higher the quality of the polished film. The XPS and AFM results show that PA-N film polished in 1% A1₂O₃ abrasive (0.3 Μm particles), NH₄OH (2% by volume), and water, has better quality compared to the other slurries investigated. With high quality PA-N films, the film surface quality affected by CMP is relatively independent of polishing time, indicating that changes in surface chemistry occur in the initial seconds of polishing.     

Nanometer-scale investigation of metal-SiC interfaces using ballistic electron emission microscopy

We report ballistic-electron emission microscopy (BEEM) investigation of Pd, Pt Schottky contacts on 6H-, 4H-SiC, and Pd/15R-SiC. Measured Schottky barrier heights of 6H- and 4H-SiC samples appear spatially uniform up to the fitting error due to noise (0.03–0.04 eV and 0.1–0.2 eV for 6H- and 4H-SiC, respectively). In 4H-SiC, we observed an additional conduction band minimum (CBM) ∼0.14 eV above the lowest CBM, which provide direct experimental verification of band theoretical calculation results. Additionally, we sometimes observed enhancement in ballistic transmittance over regions intentionally stressed by hot electron injection using BEEM. We also report recent results on Pd/15R-SiC sample indicating a higher CBM ∼0.5 eV above the lowest CBM. In Pd/15R-SiC, interesting large variations in BEEM spectra at different locations were observed, possibly suggesting an inhomogeneous metal/semiconductor interface.     

On-chip silicon light source: from photonics to plasmonics

Practical silicon photonic interconnects become possible nowadays after the realization of the practical silicon light sources,where the hybrid integrations of Ⅲ-Ⅴ semiconductors and silicon by bonding...     

Study of schottky barrier heights of indium-tin-oxide on p-GaN using x-ray photoelectron spectroscopy and current-voltage measurements

In this study, the current density-voltage (J-V) characteristic of Schottky diodes of indium-tin-oxide (ITO) contacts to p-type GaN (p-GaN) has been investigated. The calculated barrier-height value of ITO/p-GaN samples using the thermionic field-emission (TFE) model is 3.2 eV, which implies that the work function of ITO is equal to 4.3 eV. The result is supported by J-V measurements of ITO/n-type GaN Schottky diodes. On the other hand, the barrier height of ITO/p-GaN was also determined from x-ray photoelectron spectroscopy (XPS) data. The analysis of the XPS spectral shifts indicated that this observed barrier-height value of ITO/p-GaN by XPS is in good agreement with the value of 3.2 eV obtained from J-V measurements.     

扫描离子电导显微镜及其在医学研究中的初步应用

扫描离子电导显微镜(scanning ion conductance microscopy,SICM)是一种非接触式的扫描探针显微技术(scanning probe microscopy,SPM),可以实现生物样品在近生理条件下的成像.随着技术发展,目前广泛应用于生物医学领域的SICM主要包括两种:跳跃式离子电导显微技术(hopping probe ion conductance microscopy,HPICM)和外加压力模式的SICM.前者可以应用于软的、黏的、对外力或其它机械信号敏感的样品的高分辨成像;后者可以通过探针微管对样品局部施加外力刺激或化学、电学、光学或生物分子等信号,实现对样品动力学性质或相关生理过程局部的原位研究.此外,SICM技术具有良好的开放性,能够越来越多地与其它技术手段联用,极大地丰富了其在生物医学领域的应用,可用于疾病发病机理、药物作用以及临床诊断等的研究.但是,目前SICM时间分辨率较低,这制约了它在生物体系动力学行为方面的研究.     

场发射扫描电镜在现代河流沉积石英颗粒表面形态特征研究中的应用

石英具有稳定的物理化学性能,能够较好地保存各种地质营力在搬运和沉积过程中形成的微观形貌特征.这些表面形态特征可以用来反映沉积物的源区、搬运动力、沉积环境与演化历史等信息.利用场发射扫描电镜对黄河下游边滩沉积物中石英颗粒表面形态特征进行了观察研究,并统计计算了35种表面形态特征出现的频率分布.结果表明,其发育机械成因、化学成因及机械+化学成因3大类共22种表面形态特征.其中V型撞击坑大量出现;棱角—半棱角轮廓、中贝壳状断口、直形阶梯、溶蚀坑、中浮雕和高浮雕一般发育;圆形轮廓、小贝壳状断口、大贝壳状断口、弓形阶梯、曲型脊线、平行节理面、翻板、新月型撞击坑、定向溶蚀坑、溶蚀裂缝、低浮雕和弓形曲型多边形裂纹少量出现;碟形坑和黏附颗粒极少量出现.其总体表面形态特征表明其搬运时间和长距较短,在流水中并未经过长期磨蚀,棱角轮廓被保留,表面形态改造程度较弱,表面起伏程度较高.其机械形态组合说明石英颗粒处于高能水动力条件下搬运,发生过强烈地机械碰撞与磨损.发育的溶蚀坑证明搬运水体化学性质活泼,石英颗粒在受到强烈机械作用的同时,化学作用亦十分明显.获得了典型河流沉积的标志性形态特征:颗粒一般均有磨圆,以半棱角轮廓为主,随搬运距离越远磨圆度越高;表面起伏程度较高,以高、中浮雕为主;最重要的特征是机械成因形成的V型撞击坑大量发育;各种大小的贝壳状断口及阶梯共生在一起,较发育;水下化学作用明显,溶蚀现象大量出现,溶蚀坑较发育.该研究弥补了国内现代河流沉积物石英颗粒表面研究空白,虽然这些微观形貌的深层意义还有待进一步研究,但这将为沉积过程及其环境意义的研究提供新的思路和证据.     

Preparation of ultrasmooth and defect-free 4H-SiC(0001) surfaces by elastic emission machining

In this work, elastic emission machining (EEM), which is a precise surface-preparation technique using chemical reactions between the surfaces of work and fine powder particles, is applied to the flattening 4H-SiC (0001) surface. Prepared surfaces are observed and characterized by optical interferometry, atomic force microscopy (AFM), and low-energy electron diffraction (LEED). The obtained images show that the processed surface has atomic-level flatness, and the subsurface damage and surface scratches of the preprocessed surface are almost entirely removed.     

X-ray photoelectron spectroscopy study of oxide and Te overlayers on as-grown and etched HgCdTe

X-ray photoelectron spectroscopy has been used to study the low-temperature (<80°C) preparation of HgCdTe surfaces with atomic hydrogen for the purpose of CdTe passivation. Atomic hydrogen was used to etch overlayers and surfaces of liquid phase epitaxy and molecular beam epitaxy HgCdTe, CdTe, HgTe, and Te. Oxide layers were easily removed, while carbon overlayers were resistant to atomic hydrogen etching at low temperature. Both Te and HgTe are etched by atomic hydrogen, with the HgTe etch rate about twice that of Te, while CdTe and ZnTe are not etched. Chemi-mechanical polishing of liquid phase epitaxy HgCdTe left a 10 to 20Å Te overlayer that could be removed with atomic hydrogen. In all cases, exposure of HgCdTe to atomic hydrogen led to surface composition shifts to higher x-value, with an x-value plateau near x～0.6. All observations could be explained in terms of the formation of a 15Å surface layer of CdTe which blocks further etching.     

Exploring How to Increase the Brightness of Surface‐Enhanced Raman Spectroscopy Nanolabels: The Effect of the Raman‐Active Molecules and of the Label Size

Due to the surface‐enhanced Raman scattering (SERS) effect, SERS labels based on noble‐metal nanoparticles loaded with Raman‐active molecules are good candidates for ultrasensitive multiplexed assays and in vitro/in vivo imaging. However, understanding how to maximize the brightness of such labels is of paramount importance for their widespread application. The effective differential Raman scattering cross‐section (dσ_R/dΩ) of SERS labels made of pegylated gold nanoparticles loaded with various Raman active molecules (Raman reporters) is studied. It is found that proper choice of the Raman reporter and of nanoparticle size can enhance the dσ_R/dΩ by several orders of magnitude. The experimental results are understood by considering the molecular cross‐section for resonant Raman scattering and the local electromagnetic enhancement factor (G_SERS) in the nearby of gold nanoparticles. These results are useful to guide the design of SERS labels with improved performances and to provide a reference for the comparison of the absolute value of the dσ_R/dΩ of SERS labels based on metal nanoparticles.     

A review on SRAM-based computing in-memory: Circuits,functions, and applications

Artificial intelligence (AI) processes data-centric applications with minimal effort. However, it poses new challenges to system design in terms of computational speed and energy efficiency. The traditional von Neumann architecture cannot meet the requirements of heavily data-centric applications due to the separation of computation and storage. The emergence of computing in-memory (CIM) is significant in circumventing the von Neumann bottleneck. A commercialized memory architecture, static random-access memory (SRAM), is fast and robust, consumes less power, and is compatible with state-of-the-art technology. This study investigates the research progress of SRAM-based CIM technology in three levels: circuit, function, and application. It also outlines the problems, challenges, and prospects of SRAM-based CIM macros.