高纯锗中浅受主的光热电离光谱

在液氦温度附近, 运用傅里叶变换光谱以及与之相连的磁光光谱系统, 对室温电阻率约为50Ω·cm的p型高纯锗样品进行了高灵敏度的光热电离光谱的研究.从实验上确定了高纯锗样品中浅杂质光热电离的最佳温度范围, 在该温度范围内测量了样品的光热电离光谱, 指出该样品中主要杂质为浅受主硼与铝. 对杂质谱线发生分裂的两种原因, 补偿性杂质导致的快速复合以及随机应力等, 进行了分析讨论. 关键词： 高纯锗 光热电离光谱 元素半导体中的杂质和缺陷能级     

高纯硅中补偿性杂质的光热电离光谱

首先测量了高纯n型硅样品在接近液氦温度区域内随温度变化的光热电离光谱,确定了硅样品的最佳光热电离温度范围. 在该温度范围内,在有本征带隙光照射条件下,测量了样品的高分辨率光热电离光谱,同时观察到了来自主要浅杂质施主磷以及补偿性杂质硼的正信号. 随后,应用外加磁场,对硼的光热电离光谱进行了研究,发现来自硼的光热电离信号,在外加磁场作用下,发生了由正向负信号的转变. 通过对该现象进行分析讨论,排除了该现象是温度效应的可能,指出普遍用来解释补偿性杂质光热电离响应的Darken模型存在不足,而少数载流子快速复合模 关键词： 高纯硅 光热电离光谱 元素半导体中的杂质和缺陷能级 少数载流子快速复合     

高纯硅中补偿性杂质的光热电离光谱

首先测量了高纯n型硅样品在接近液氦温度区域内随温度变化的光热电离光谱，确定了硅样品的最佳光热电离温度范围. 在该温度范围内，在有本征带隙光照射条件下，测量了样品的高分辨率光热电离光谱，同时观察到了来自主要浅杂质施主磷以及补偿性杂质硼的正信号. 随后，应用外加磁场，对硼的光热电离光谱进行了研究，发现来自硼的光热电离信号，在外加磁场作用下，发生了由正向负信号的转变. 通过对该现象进行分析讨论，排除了该现象是温度效应的可能，指出普遍用来解释补偿性杂质光热电离响应的Darken模型存在不足，而少数载流子快速复合模     

半导体中浅杂质的傅里叶变换光热电离光谱

本文报道与快扫描傅里叶变换红外光谱仪相结合的光热电离光谱实验装置和测量系统。采用该系统高分辨率、高灵敏度地研究和测量高纯锗和高纯硅中的剩余浅杂质获得成功。在P型超纯Ge中发现浓度低达10⁸cm^-3的硼受主杂质的光热电离谱线,而探测灵敏度则至少可达10⁷cm^-3;在n型高纯Si中观测到Li-O复合型浅施主中心D(Li,O);施加本征激发光后在P型高纯Si中同时观察到B受主和P施主的跃迁谱线系。此外,在Si,Ge中均观察到 关键词：     

ZnSe:Al发光光谱的研究

本文用热扩散的方法在Zn饱和蒸气压下,把Al掺杂到高纯ZnSe单晶中,通过77K下的光致发光光谱研究了Al杂质的发光行为,讨论了施主一受主对发射强度、自激活中心发射强度随掺杂温度的变化规律以及与Zn饱和蒸气压的关系.本文首次报道了在300℃～900℃温度范围内进行Al掺杂的ZnSe的发光规律.     

发射光谱测定微量稀土杂质用的一种新的载体KBH4的研究

介绍了高纯稀土氧化物中微量稀土杂质的光谱测定方法，本工作用碳粉做缓冲剂，ＫＢＨ４做载体，用化学方法将大量稀土分离掉，而后对余下微量和稀土杂质进行光谱测定。只要取样量不少于１克，则可测定的纯度为９９．９９９９５％的稀土样品。     

井型高纯锗探测器体源样品无源效率刻度

采用蒙特卡罗程序MCNP建立物理模型,对井型高纯锗探测器的效率进行虚拟刻度。模拟计算在密度为0.4,1.2 gcm-3的6种不同成分环境样品中,探测器对射线的探测效率,当能量高于0.10 MeV时,体源样品的探测效率主要与样品密度、射线能量相关。以土壤、水和植物油样品为代表,结合所选取的函数模型,确定了密度范围0.1~1.6 gcm-3的固体源、密度1.0 gcm-3的水溶液和密度0.92 gcm-3的油溶液体源的效率函数及参数。实验采用标准源,对探测效率模拟结果进行了验证,探测效率的模拟值与实验值符合较好,二者误差均在3%以内。说明MCNP程序可以较为准确地模拟计算井型高纯锗探测器对射线的探测效率,验证了该无源效率刻度方法的准确性和可行性。     

应变Si1-xGex层中p型杂质电离常温和低温特性

本文采用解析的方法计算了应变Si1-xGex层中p型杂质电离度与Ge组分x、温度T以及掺杂浓度N的关系.发现常温时,在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度的先变小,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加先变大,而后几乎不变;重掺杂时,杂质电离能变为0后,杂质电离度为1.低温下,轻掺杂时,载流子低温冻析效应较为明显,杂质的电离度普遍较小,当掺杂浓度大于Mott转换点时,载流子冻析效应不再明显,电离率迅速上升到1.在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度先变小,后变大,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加变大;重掺杂时,杂质电离能变为0后,杂质电离度为1.     

激光剥蚀-电感耦合等离子体质谱法测定高纯铪中10种杂质元素

高纯铪由于具有独特的理化性质,在核反应堆、等离子切割机、光学元件等方面有着重要的应用。高纯铪中杂质的种类和含量会影响高纯铪的物理化学性能,应用中对高纯铪纯度的要求也越来越高,这就对高纯铪的分析检测技术提出了更高的要求。激光剥蚀-电感耦合等离子体质谱法（LA-ICP-MS）是激光剥蚀进样技术与电感耦合等离子体质谱联用,可以直接分析固体样品,并且方法前处理简单,可以避免样品前处理过程中引入杂质,是一项高效、快速、精密的分析技术,在环境、地质、冶金、燃料能源、材料、生物医药、考古等领域广泛应用。所以,激光剥蚀-电感耦合等离子体质谱法（LA-ICP-MS）是高纯金属杂质元素最佳检测方法之一。还未见有应用LA-ICP-MS于高纯铪样品的报道。用LA-ICP-MS对高纯铪中10种杂质元素（Al,Sc,Ti,Fe,Ni,Cu,Mo,Ag,Sn,W）进行定量分析。为了降低激光剥蚀过程中元素的分馏效应,提高信号灵敏度和稳定度,对激光剥蚀参数进行优化实验。确定了激光剥蚀的最优仪器参数为：氦气流量600 mL·min-1,激光能量90%,剥蚀孔径150 μm,激光扫描速度60 μm·s-1,激光脉冲频率20 Hz。经实验优化后的ICP-MS仪器工作参数为：RF功率1 450 W,射频匹配电压1.8 V,载气流量0.85 L·min-1,冷却器流量0.85 L·min-1,采样深度7.5 mm。在最优参数条件下,利用内控标样建立工作曲线,各杂质元素标准曲线的线性相关系数为0.993 6～0.999 8。采集载气空白的信号强度,平行测定11次,以3倍空白信号的标准偏差所对应的含量作为元素的检出限,得到各元素的检出限为0.001~0.08 μg·g-1。将高纯铪制成尺寸合适的样品,用硝酸洗去样品表面的氧化物,将其装入剥蚀池中,运用线扫描剥蚀方式,在最佳仪器工作条件下,对三个高纯铪样品中的10种杂质元素进行定量分析。实验结果显示,杂质元素含量为0.17～36.76 μg·g-1,相对标准偏差为1.4%～20%,精密度良好。以184W为例,将LA-ICP-MS法和ICP-MS法的测定结果进行t检验,三个样品的t值分别为2.14,1.64和2.11,均小于显著性水平为0.05时的临界值（t_{0.05, 12}=2.18）,说明LA-ICP-MS法和ICP-MS法的测定结果在置信度为95%时没有显著性差异,即正确度良好。所以,该方法正确度和精密度良好,可用于高纯铪中杂质的定量分析。     

IC用高纯试剂中金属杂质分析

对ＨＣｌ，ＨＦ和ＨＮＯ３三种ＭＯＳ级高纯试剂中１８种金属杂质用发射光谱进行分析研究，取２０ｍｌ样品，加入适量甘露醇络合硼杂质，在有机玻璃防尘罩内低温挥发基体富集杂质，最后将杂质溶液转移到一对平头电极上，用电弧光谱进行测定。检测限为０．２－４．０（ｎｇ／ｍｌ），加入标准的回收率绝大部分在９０％以上。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.