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A Novel Contactless Method for Characterization of Semiconductors:Surface Electron Bean Induced Voltage in Scanning Electron Microscopy 下载免费PDF全文
We present a novel contactless and nondestructive method called the surface electron beam induced voltage (SEBIV) method for characterizing semiconductor materials and devices.The SEBIV method is based on the detection of the surface potential induced by electron beams of scanning electron microscopy (SEM).The core part of the SEBIV detection set-up is a circular metal detector placed above the sample surface.The capacitance between the circular detector and whole surface of the sample is estimated to be about 0.64pf.It is large enough for the detection of the induced surface potential.The irradiation mode of electron beam (e-beam) influences the signal generation When the e-beam irradiates on the surface of semiconductors continuously,a differential signal is obtained.The real distribution of surface potentials can be obtained when a pulsed e-beam with a fixed frequency is used for irradiation and a lock-in amplifier is employed for detection.The polarity of induced potential depends on the structure of potential barriers and surface states of samples.The contrast of SEBIV images in SEM changes with irradiation time and e-beam intensity. 相似文献
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La2-xSrxCuO4(以下称LSCO)是最早发现的高温超导体之一.当x≈0.15时,它具有最高的超导转变温度,Tc=33K.对于x<0.02的轻度掺杂,材料的低温相是反铁磁绝缘体.在室温以上时,层状化合物LSCO晶格具有四方对称性;当冷却样品通过特征温度To,将发生从四方到正交的结构相变.此时,晶体发展出一种被称为孪晶的畴结构,被畴壁分开的相邻区域具有不同的晶轴取向.正交结构的晶格常数a=05339nm,b=0.5422nm,两者相差约1%.为了探求高温超导机理,LSCO曾被广泛深入地研究.由于在超导LSCO中根本不存在41meV反铁磁自… 相似文献
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The discovery of the induced magnetic field of Callisto that is a satellite of Jupiter has been interpreted as evidence for a subsurface salty liquid-water ocean,so we consider a layered structure of callisto,i.e.,a rock-metal core,an outer layer of ice and a middle layer of ocean.For the rock-metal core we try to indicate how the temperature,pressure and mass density depend on the depth.Due to motionn across the magnetic field of Jupiter in a plasma environment,the ice shell of Callisto must be broken down by electric current. 相似文献
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Mao Xiang Wang Xiang Ming Meng Man Zhou Zhu Qing Xiang Guo 《中国化学快报》2007,18(11):1403-1406
A novel fluorescence enhancement Cu~(2 ) chemosensor derived from coumarin was prepared.Emission study found that it exhibits evident Cu~(2 )-amplified fluorescence prior to Co~(2 ),Pb~(2 ),Mg~(2 ),Mn~(2 ),Ni~(2 ),Zn~(2 ),Fe~(3 ),Ag~ and Cd~(2 ),and the largest emission enhancement factor is about 9 at a ratio of 2:1 (chemosensor 1/Cu~(2 )). 相似文献
17.
分子印迹智能水凝胶的研究进展 总被引:1,自引:0,他引:1
智能水凝胶可以响应外界环境(如温度、pH、溶剂、离子强度、电场、磁场、光、压力和特异分子等)的变化,发生可逆体积相变,从而具有控制释放的能力.将分子印迹技术引入智能水凝胶,制备分子印迹智能水凝胶,不仅可以保持其环境响应性,更赋予其对特异分子的识别性能,从而可以根据外界环境的变化控制其对特定分子记忆功能的开关,实现自动识别并结合或释放特定分子.它有望应用于药物控释、生物传感和免疫分析等领域.本文综述了分子印迹智能水凝胶的研究现状,讨论了其目前所面临的挑战,并展望了其发展前景. 相似文献
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Hua Lin XIE Yu Jie LI Xi Du NIE Li Bo LI 《中国化学快报》2006,17(7):945-948
Because of its high sensitivity, wide dynamic range and relative freedom from interferences, inductively coupled plasma mass spectrometry (ICP-MS) has been developed for the determination of trace and ultra-trace levels of elements in various fields1. Due… 相似文献
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本文提出在原子吸收光谱测定中,采用Smith-Hieftje法校正背景时,空心阴极灯供电条件(即最佳宽窄脉冲电流)的选择依据和选择方法;并给出24个常见元素的宽窄脉冲电流的选定结果。 相似文献
20.
PengZHANG JiCunREN ZuoJunSHEN 《中国化学快报》2004,15(9):1091-1094
In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma. 相似文献