共查询到20条相似文献,搜索用时 93 毫秒
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采用光抽运-太赫兹探测技术研究Cd0.96Zn0.04Te的载流子弛豫和瞬:态电导率特性.在中心波长800 nm的飞秒抽运光激发下,Cd0.96Zn0.04Te的载流子弛豫过程用单指数函数进行了拟合,其载流子弛豫时间长达几个纳秒,且在一定光激发载流子浓度范围内随光激发载流子浓度的增大而减小,这与电子-空穴对的辐射复合有关.在低.光激发载流子浓度(4.51×1016—1.81×1017 cm-3)下,Cd0.96Zn0.04Te的太赫兹(terahertz,THz)瞬态透射变化率不随光激发载流子浓度增大而变化,主要是由于陷阱填充效应造成的载流子损失与光激发新增的载流子数量近似.随着光激发载流子浓度继续增大(1.81×1017—1.44×1018 cm-3),THz瞬态透射变化率随光激发载流子浓度的增大而线性增大,是由于缺陷逐渐被... 相似文献
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对所研制的短波光伏碲镉汞器件进行了变温电流-电压特性和低频噪声研究,测试温度范围255—293K.实验结果表明随着温度的下降,器件的优值因子R0A从45×103Ωcm2增加到7×104Ωcm2.器件在低频区的主要噪 声成分是1/f噪声和产生-复合噪声,在高频区主要是散粒噪声.在测试的偏压内,器件的1/f噪声功率谱密度与流过器件的电流的平方成正比,器件的Hooge系数为3×10-4—7×10-4.从噪声 功率谱密度曲线分析中得到产生-复合噪声的特征时间常数τ,通过τ的温度特性得到了器件的深能级.
关键词:
碲镉汞
优值因子
低频噪声
深能级 相似文献
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本文提出了一种新的测量半导体材料中少数载流子寿命的方法。这方法是测量触针下分布电阻的光电导衰退。这方法具有下列优点:(1)样品不需要切成一定形状;(2)在样品上不需要做固定电极;(3)可以检验不均匀的材料;(4)不需要一定的表面处理;(5)仪器简单,操作方便;(6)有一定的准确度。文中对表面复合速度以及光线在样品中的吸收深度的影响进行了理论分析;同时对Ge和Si样品的实验数据进行了讨论。用这方法测得的寿命基本上与其他方法的结果符合。
关键词: 相似文献
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研究了典型红外激励发光材料XS:Ra,Sm(X=Sr,Ca;Ra=Ce,Eu)的激励发光过程中电子与空穴的俘获中心及其转移过程,通过激发前后的红外吸收光谱的差异及吸收差与光激励谱的细微结构说明,电子俘获中心并不是Sm3+离子,但与Sm3+离子处于相邻的空间位置关系,Sm3+离子在载流子俘获与复合的过程中也没有发生价态或数量的变化,进一步的EPR谱研究表明Eu2+离子的价态在激发前后也没有发生变化。与共价性强的Ⅲ-Ⅴ族半导体晶体不同的是,在这类离子性较强的晶体中,载流子被杂质所引起的晶格缺陷而非杂质本身俘获。在多种发光中心的情况下,不同的激发波长可以使空穴束缚在不同的发光中心附近,随后产生不同的光激励发光。 相似文献
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采用Z扫描和抽运-探测实验技术, 在波长为532 nm、脉冲宽度为41 fs的条件下测得ZnSe晶体的双光子吸收系数, 并获得了不同激发光强下的自由载流子吸收截面、电子-空穴带间复合时间和电子-声子耦合时间. 研究发现, 随着激发光强的增大, 自由载流子吸收截面减小, 复合时间变短. 当激发光强增大导致载流子浓度大于1018 cm-3时, 抽运-探测信号出现明显改变, 原因归结为强光场激发导致样品在短时间内带隙变窄和电子-空穴等离子体的形成. 相似文献
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The influence of anharmonic renormalization effects on the decay dynamics of coherent longitudinal optical phonons is investigated from a microscopic point of view. Time-resolved coherent anti-Stokes Raman signals are calculated for GaP on the basis of a full phonon dispersion calculation, and the relevant decay channels are identified and compared. Anharmonic renormalization effects are found to induce non-Markovian behaviour of the decay dynamics and lead to a decrease of the decay time. The renormalization effects only depend on the special properties of the phonon dispersion of the given material. This underlines the intrinsic nature of the non-Markovian decay dynamics of phonons for any material. Non-Markovian dynamics of the decay of coherent LO-phonons is calculated for GaP and result in a 30% faster decay signal than the corresponding Markovian dynamics. 相似文献
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Elmar Trautenberg 《Zeitschrift für Physik B Condensed Matter》1973,16(2):163-179
Generally electronic processes in semiconductors are accompanied by phonon excitations. These excitations themselves influence
electronic transitions. On the other hand excited phonons decay by interaction with other impurities in the crystal, which
act as a heat-bath. The resulting competition between phonon exciting electronic processes and phonon decay is described by
Pauli's master equation. By expansion of its solutions into phonon decay solutions the problem can be separated into different
decay equations for phonons and electrons as proposed by Stumpf. Assuming linear phonon-heat-bath coupling the phonon decay
equation can be solved exactly by a generating function technique. The appropriate phonon decay frequencies are calculated
for a simple heat-bath model. 相似文献
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The emission spectra and its time decay in PbCl2 at low temperature are reported. Three emission bands lying at 3.81 (uv), 2.93 (blue) and 2.60 eV are found for the photo-excitation in the intrinsic absorption region, at 4.2 K. An exponential decay with decay time of 11.4 μs is observed for the uv emission. For the blue emission two kinds of time decay spectra are observed: a second order process below 10 K and an exponential decay above 14 K. The mechanisms of these emission are discussed by taking into account the above results. 相似文献
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Yu. P. Gangrskii 《Physics of Particles and Nuclei》2007,38(6):743-761
The experimental data on rare modes of radioactive decay of fission fragments is reviewed. These decay modes are due to a large excess of neutrons and a high energy of β decay fragments. They appear in delayed emission of various particles after the β decay (several neutrons, α particles, or heavy clusters) and excitation of unusual states (giant multipole resonances and shape isomers). The β decay and internal conversion of γ radiation into bound states of the atomic electron shell and their influence on the probability of secondary particle emission are considered. The possibility is discussed of observing decays that have not yet been experimentally detected, but theoretically predicted, as well as information on the nuclear structure obtained by studying such decay modes. 相似文献
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α decay energies of 323 heavy nuclei with Z≥82 are evaluated with a macroscopic-microscopic model.In this model,the macroscopic part is treated by the continuous medium model and the microscopic part consists of shell and pairing corrections based on the Nilsson potential.α decay half-lives are calculated by Viola-Seaborg formula.The results of α decay energies and half-lives are compared with experimental values and satisfactory agreement is found.The recoiling effect of the daughter nucleus on α decay half-life is also discussed. 相似文献
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N. G. Kanev 《Acoustical Physics》2017,63(6):731-736
The laws of sound decay in a cubic room, one wall of which is absorbing and the other scattering, are obtained. It is shown that under certain conditions, sound decay in a room occurs nonexponentially and the shape of the decay curve depends on the scattering coefficient of the walls. This makes it possible to suggest a method for measuring the scattering coefficient by the analysis the decay curve when the walls have sound-scattering materials and structures. Expressions are obtained for approximating the measured decay curve, and the boundaries of the method’s applicability are determined. 相似文献
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David Apsel 《General Relativity and Gravitation》1981,13(6):605-607
A number of experiments show that the decay lifetimes of muons bound to atomic nuclei are longer than the decay lifetimes of free muons. The special relativistic time dilation predicts decay lifetime dilations that are substantially smaller than the observed decay lifetime dilations. In this paper it is shown that adding a recently predicted electro-magnetic time dilation (analogous to the gravitational time dilation) to the special relativistic time dilation gives a total time dilation that agrees with the observed decay lifetime dilations. 相似文献
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Alexander D. Panov 《Physics letters. A》1999,260(6):441-446
Different perturbation mechanisms of the spontaneous decay constant are shown: the inelastic interaction of emitted particles with particle detector, decay onto an unstable level, Rabi transition from the final state of decay (electromagnetic field domination) and some others are really the special kinds of one general effect – the perturbation of the decay constant by dissipation of the final state of decay. Such phenomena are considered to be Zeno-like effects and the general formula for the perturbed decay constant is deduced. 相似文献
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For a chaotic, area-preserving map on the torus, we study the decay of correlations in detail. Taking as observables the square-integrable functions, we find examples of decay rates which are algebraic, exponential, and faster than exponential. For correlations that decay exponentially the rate is sensitive to the choice of function. The implications for numerical experiments of this nonuniformity in the decay are discussed. 相似文献