先进工艺对MOS器件总剂量辐射效应的影响

器件栅氧厚度的减小、场氧工艺的改变以及衬底材料的不同等都将导致MOS器件的总剂量辐射效应发生改变.亚阈斜率、阈值电压漂移、衬底技术和场氧抗辐射能力已经成为器件按比例缩小给器件带来冲击的最主要的四个方面.综述了上述条件、高k介质/硅系统以及选择SOI材料作为衬底材料对MOS器件总剂量辐射效应的影响.     

半导体材料辐射效应的表征与分析

在辐射环境中,电子系统常用的半导体器件及电路会出现不同程度的性能退化,甚至发生失效.其根本原因来源于辐射致组成半导体器件的材料内部缺陷的产生和积累.表征和分析辐射致材料内部缺陷的种类、浓度、分布等信息,是半导体材料辐射效应研究的重要内容.从辐射致缺陷微观形貌、结构特征,及其引起的宏观电效应三方面,归纳总结了几种重要的半导体材料辐射效应的表征和分析方法,分析了每种方法的优缺点及适用范围,并指出半导体材料辐射效应表征与分析技术发展的方向,可为电子器件、半导体材料辐射效应领域的研究人员提供参考.     

Al/SRO/Si结构中横向电压作用下的电荷俘获效应

利用Al/SRO/Si MOS,对富硅二氧化硅(SRO)材料在横向电压作用下的电荷俘获效应进行了研究.用LPCVD法在n型Si衬底上沉积SRO材料,通过C-V测量研究其电荷俘获性质.发现对于n型Si衬底,在横向电压作用下,SRO层能够俘获正电荷,电荷俘获效应与SRO层的性质有关.基于电位在器件内部的分布及诱导pn结的形成,提出了一个简单的物理模型来解释所得到的实验结果.     

Al/SRO/Si结构中横向电压作用下的电荷俘获效应

利用Al/ SRO/ Si MOS,对富硅二氧化硅(SRO)材料在横向电压作用下的电荷俘获效应进行了研究.用L PCVD法在n型Si衬底上沉积SRO材料,通过C- V测量研究其电荷俘获性质.发现对于n型Si衬底,在横向电压作用下,SRO层能够俘获正电荷,电荷俘获效应与SRO层的性质有关.基于电位在器件内部的分布及诱导pn结的形成,提出了一个简单的物理模型来解释所得到的实验结果     

红外焦平面空间抽样特性分析与测试

尽管自然场景热像的空间频率远小于其可见光图像,在凝视型红外焦平面空间积分抽样过程中,被探测场景的空间频率也往往要远高于红外焦平面阵列探测单元重复频率的一半,这种欠抽样所产生的折叠混淆效应将严重地损害红外热图像的质量。本文建立了空间积分抽样的相位理论模型,分析了该模型在空间积分抽样折叠混淆效应的消减,以及对中心布里渊区中真假频谱积分比的测试等方面的应用。     

电影胶片数字扫描图像分辨力的选择

主要论述了35 mm胶片的信息存储容量和调制传递函数(MTF)特性,通过综合分析MTF曲线、空间频率、清晰度和混叠失真等参数来确定最适合数字中间片的扫描分辨力,以及选择4k扫描分辨力的优势.     

色散效应对GaAs太阳电池双层减反射膜的影响

考虑双层减反射膜材料的折射率色散效应,采用光学干涉矩阵法计算了SiO2/ZnSe和SiO2/ZnS两种GaAs太阳电池双层减反射膜的反射率与波长的函数曲线,以及加权平均反射率随着顶层减反射膜SiO2厚度变化的函数曲线,并与未考虑色散效应的情况进行了对比.计算结果表明,色散效应对双层减反射膜的反射率有较大的影响,特别是对300～500nm波长范围的影响更大,且对不同材料的减反射膜的影响也是不同的.与未考虑色散效应的情况相比,考虑色散效应后,SiO2/ZnSe双层减反射膜的最小加权平均反射率从1.14%增加到1.55%,而SiO2/ZnS双层减反射膜的最小加权平均反射率却从1.49%减小到1.46%.     

色散效应对GaAs太阳电池双层减反射膜的影响

考虑双层减反射膜材料的折射率色散效应,采用光学干涉矩阵法计算了SiO2/ZnSe和SiO2/ZnS两种GaAs太阳电池双层减反射膜的反射率与波长的函数曲线,以及加权平均反射率随着顶层减反射膜SiO2厚度变化的函数曲线,并与未考虑色散效应的情况进行了对比.计算结果表明,色散效应对双层减反射膜的反射率有较大的影响,特别是对300～500nm波长范围的影响更大,且对不同材料的减反射膜的影响也是不同的.与未考虑色散效应的情况相比,考虑色散效应后,SiO2/ZnSe双层减反射膜的最小加权平均反射率从1.14%增加到1.55%,而SiO2/ZnS双层减反射膜的最小加权平均反射率却从1.49%减小到1.46%.     

高k栅介质MOSFET的栅电流模型

提出了包括有限势垒高度下反型层量子化效应以及多晶硅耗尽效应在内的直接隧穿电流模型.在该模型的基础上,研究了采用不同高介电常数栅介质材料时MOSFET的栅电流与介质材料的介电常数、禁带宽度及和Si导带不连续等参数之间的关系.所获得的结果能够为新型栅介质材料的选取提供依据.     

高k栅介质MOSFET的栅电流模型

提出了包括有限势垒高度下反型层量子化效应以及多晶硅耗尽效应在内的直接隧穿电流模型.在该模型的基础上,研究了采用不同高介电常数栅介质材料时MOSFET的栅电流与介质材料的介电常数、禁带宽度及和Si导带不连续等参数之间的关系.所获得的结果能够为新型栅介质材料的选取提供依据.     

光致聚合物全息光栅曝光特性的研究

为了研究采用由曙红做染料、丙烯酰胺和亚甲基双丙烯酰胺构成的光致聚合物制成的全息透射光栅的曝光特性,用实验的方法探索了光栅空间频率、曝光强度、曝光时间等因素对该透射光栅衍射效率的影响。实验表明,聚合物全息透射光栅空间频率,曝光强度,曝光时间都有一个互相关联的最佳范围,在这一范围内衍射效率能达到最大值。当聚合物光栅在空间频率为2751 line/mm附近,曝光强度在12mW~15mW之间,曝光量在770mJ/cm2左右时,衍射效率最大。最大衍射效率能达到75%左右,在全息光栅中衍射效率较高。     

任意三维表面微型光器件的灰度光刻技术

使用传统的微加工技术,如各向异性或各向同性干刻蚀、湿刻蚀只能加工有限形貌的表面,为了克服这一缺点,发展了多层掩模技术、激光三维立体光刻、电子束直接写入技术等许多三维微加工技术。灰度光刻最被看好,它通过灰度掩模把加工光束能量密度分布调制成不同的形状,对光刻胶进行曝光,微型器件一次成形,不需要移动掩模或移动加工晶片,也不需要对光刻胶进行热处理,只需要对掩模版进行一定的编码和标准的光刻设备,容易和其他IC工艺相兼容,实现系统芯片结构的制作。本文分析了它的物理机制、掩模类型、编码过程、约束条件和优化方法。     

MMSE techniques for space diversity receivers in OFDM-based wireless LANs

This paper studies the application of the minimum mean square error (MMSE) beamformer to orthogonal frequency division multiplexing (OFDM)-based wireless local area networks. The questions here addressed are mainly the design with finite-length data and the choice of the OFDM signal domain where the beamformer is applied, either frequency or time. As OFDM signals need more samples than other modulations to stabilize the estimation of the signal statistics, how to exploit the finite-length training sequence provided for the design of equalizers becomes an important issue. The paper also shows that the usual frequency processing in OFDM is not always the best choice for the spatial beamforming, mainly for channels with a very high delay spread. Then, time processing turns out to be the best suited approach in terms of the tradeoff between performance and complexity. Additionally, novel modifications of the MMSE spatial filter are proposed to improve the raw bit-error rate performance: 1) a temporal semiblind approach that exploits the cyclic prefix and 2) windowing in the frequency domain.     

与光谱色散匀滑技术联用的衍射光学器件的优化设计

基于空间频谱,对光谱色散匀滑(SSD)技术与衍射光学器件(DOE)联用的焦面光强分布进行了严格的理论分析。与光谱色散匀滑技术联用前后,衍射光学器件焦面光强分布均可转化为一系列不同频率、不同复振幅的正余弦函数的叠加。光谱色散匀滑技术对衍射光学器件焦面光强分布空间频谱进行调制,该调制不仅与光谱色散匀滑参数,还与衍射光学器件相位分布有关。该技术使得衍射光学器件焦面光强分布变得更平缓,但要获得良好的联用性能,需根据光谱色散匀滑参数进行衍射光学器件的优化设计。在某一给定的光谱色散匀滑参数条件下,进行了衍射光学器件的优化设计。结果表明,与光谱色散匀滑技术联用后,衍射光学器件对入射波前畸变的宽容度有较大提高。     

Fabrication of Self-Organized Optical Waveguides in Photo-induced Refractive Index Variation Sol–Gel Materials With High-Index Contrast

Using photo-induced refractive index variation sol-gel materials, we fabricated a self-organized lightwave network (SOLNET), which is a concept of optical waveguides self-organized in photosensitive materials, whose refractive index increases by write beam exposure. The refractive index of the sol-gel materials increases from 1.65 to 1.85 when exposed to UV light/blue light and baking. When write beams with a wavelength of 405 nm are introduced into the sol-gel thin film under baking at 200degC, self-focusing is induced and a SOLNET is formed. In this study, we evaluated the light confinement effect and coupling efficiencies of the fabricated SOLNET. The half-width of the output beam spot decreases from 23.8 to 11.8 mum, and the coupling efficiencies increase as write beam intensity decreases from 1.0 to 0.1 mW. These results show that SOLNET widths become narrow when write beam intensity is reduced; thus, SOLNETs formed with a low write beam intensity produce a strong light confinement effect. Furthermore, during their formation, SOLNETs were found to be drawn toward reflective portions of the sol-gel thin film, such as defects or silver paste droplets, indicating that a reflective SOLNET is formed. We have shown that photo-induced refractive index variation sol-gel materials are promising materials for SOLNET fabrication. To create actual connections between nanoscale optical circuits, further work is necessary to optimize the baking temperature and write beam intensity required for nanoscale SOLNET formation.     

共振拉曼光谱法检测人体皮肤中类胡萝卜素的研究

类胡萝卜素作为一种强抗氧化剂在人体的抗氧化防御系统中起重要作用。它在人体中的含量可以用来表征人体的健康状况。为了检测人体中的类胡萝卜素,对用共振拉曼光谱法检测人体皮肤中类胡萝卜素进行了实验研究。经过反复实验获得了最佳实验参数。如选择测量部位拇指内侧,入射波长473nm,入射光强度20mW,曝光时间5s。同时通过甘油匹配的方法增加了探测到的拉曼信号的强度。利用拟合差分算法有效去除了荧光背景噪声,获得了明显的人体皮肤中类胡萝卜素的拉曼光谱。     

Optical wavelength converters

Devices and techniques for shifting the frequency/wavelength of an optical carrier wave are reviewed, with particular reference to applications in wavelength/frequency division multiplexed optical communication systems. Considered first are devices which make use of semiconductor laser amplifiers or oscillators. Some of these techniques come close to satisfying the requirements for a suitable wavelength shifter, though none appear to offer the potential for a transparent network independent of data modulation format. A second main category, using nonlinear optical materials, promises to satisfy the requirements for frequency translation in a network which is fully transparent to the modulation format. However, the conversion efficiencies currently available appear too low for cost-effective communication systems engineering so that further advances in nonlinear optical materials/techniques are still required. It seems likely that guided wave techniques will provide the best means of improving the efficiency by increasing the interaction length and the optical intensity for a given power. Schematic examples of such a converter are discussed. All of the existing techniques have some deficiencies compared to an ideal system so that wavelength conversion for optical communication systems is still a problem in search of a good solution     

CCD摄像机新型光控技术研究

以往的CCD摄像机通过曝光时间和信号增益调节光照强度时,二者不能被最优配置运用,难以最大限度的发挥它们的调光功效,特别是对于光照强度变化剧烈,动态范围大的状况,画面不清晰。针对上述不足,将直方图均衡化法进行一定的改进,精确配置曝光时间,优化信号增益系数,实现曝光时间与信号增益的最优化配置。经过实验验证,画面效果得到明显改善,调整时间不超过40ms,系统运行稳定、可靠。     

Enhancement of the interaction between low‐intensity R.F. e.m. fields and ligand binding due to cell basal metabolism

Power absorption by biological tissues, due to lowintensity electromagnetic exposure at radio frequencies, as those generated by personal telecommunication systems, is typically negligible. Nevertheless, the electromagnetic field is able to affect biological processes, like the binding of a messenger ion to a cell membrane receptor, if some specific conditions occur. The depth of the attracting potential energy well of the binding site must be comparable with the radio frequency photon energy. The dependance of the binding potential energy on the spatial coordinates must be highly nonlinear. The ion–receptor system, in absence of the exogenous electromagnetic exposure, must be biased out of thermodynamic equilibrium by the cell basal metabolism. When the above conditions concur a lowintensity radio frequency sinusoidal field is able to induce a steady change of the ion binding probability, which overcomes thermal noise. The model incorporates the effects of both thermal noise and basal metabolism, so that it offers a plausible biophysical basis for potential bioeffects of electromagnetic fields, e.g., those generated by mobile communication systems.     

低强度超声对鼻咽癌细胞线粒体膜电位的影响

目的:观察低强度超声对鼻咽癌细胞线粒体膜电位的影响.方法:以低强度超声(频率1.7 MHz,剂量1.35W/cm2)辐照鼻咽癌细胞,采用Rhodamine123染色送CLSM下检测鼻咽癌细胞线粒体膜电位的变化.结果:超声波能够量著损伤鼻咽癌CNE2细胞线粒体,辐照后孵育4h,CLSM 下光吸收值与对照组相比显著降低,结...