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本文叙述测定半导体扩散层表面浓度、P-n结深度及扩散系数的霍耳效应法。导出了求算半导体扩散层表面浓度、P-n结深度及扩散系数的一组积分公式。对砷由气相扩散入锗这一情况进行了详细研究:对上述公式进行数值积分并给出一系列图线,利用这些图线从实验值求得表面浓度等上述参数。实验表明:此法所测得的结深度和表面浓度分别与光干涉法直接测得的结深度和平均电导法测得的表面浓度,在误差范围内很好符合;而且此法所测得的扩散系数与B?senberg用电容法测得的也极为接近。扩散系数与温度的关系为D=2.3exp(-2.36/(kT)),当N0=1014厘米-3;D=1.7exp(-2.36/(kT)),当N0=1016厘米-3。 相似文献
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对132MeV 16O+197Au反应产生的裂变碎片和巨偶极共振γ射线进行了符合测量,得到了E=92MeV的高激发213Fr的γ衰变谱和γ角关联谱.观测到复合核巨偶极共振γ角关联谱存在很大的各向异性.利用改进的统计模型程序分析了实验数据,不考虑裂变延迟时,统计模型计算可以很好拟合地实验结果.通过对γ角关联谱的理论计算与实验结果的比较,可以得出高激发213Fr核(E=92MeV)的形状从集体长椭球向非集体扁椭球变化. 相似文献
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利用能量为60MeV的11B束流, 通过100Mo(11B, 5n)106Ag熔合蒸发反应布居106Ag的高自旋态, 用15台带BGO反康的HPGe探测器进行在束γ谱学测量. 通过γ-γ符合矩阵开窗分析和DCO比值分析, 建立了106Ag新的能级纲图, 观测到26条新γ跃迁. 与相邻同位素奇奇核104Rh比较, 106}Ag中带1和带2具有A≈100区手征二重带的3个特征, 推测它们可能是基于πg9/2⊙υh11/2组态的手征二重带. 但它们的角动量顺排不一致, 在实验上还需进一步的测量研究. 相似文献
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对使用金属有机物汽相沉积法生长的AlGaN/AlN/GaN结构进行的变温霍尔测量,测量结果指出在AlN/GaN界面处有二维电子气存在且迁移率和浓度在2K时分别达到了1.4×104cm2·V-1·s-1和9.3×1012cm-2,且在200K到2K范围内二维电子气的浓度基本不变,变磁场霍尔测量发现只有一种载流子(电子)参与导电.在2K温度下,观察到量子霍尔效应,Shubnikov-de Haas (SdH) 振荡在磁场约为3T时出现,证明了此结构呈现了典型的二维电子气行为.通过实验数据对二维电子气散射过程的半定量分析,推出量子散射时间为0.23ps,比以往报道的AlGaN/GaN结构中的散射时间长,说明引入AlN层可以有效减小合金散射,进一步的推断分析发现低温下以小角度散射占主导地位. 相似文献
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对近几年来清华大学物理系核物理研究组原子核高自旋态实验研究的一些新进展进行了介绍.内容包括两个部分:第一部分介绍通过国际合作,利用测量裂变瞬发γ谱方法对A=140丰中子核区的奇A核143,145Ba,145,147La等的极形变研究的进展.第二部分简述对A=130缺中子核区的134,137,138Ce及122Ba等核高自旋态研究,包括形状驱动、八极关联、集体回弯等效应. 相似文献
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《Solid State Ionics》1988,26(3):237-241
A simple method with three electrodes has been used to measure the diffusion coefficient of the mobile Cu+ ion in the mixed conductor Cu3VS4 on the basis of the ambipolar diffusion theory. By this method we find that the diffusion coefficient is about 1×10−7 cm2/s at 300K with an activation energy of 0.44eV. 相似文献
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《Superlattices and Microstructures》1999,25(1-2):21-27
We report on investigations of the ambipolar diffusion process in n-i-p diodes and n-i-p-i doping superlattices performed by a new all-optical pump-and-probe technique. This new technique allows not only the determination of the ambipolar diffusion coefficient but also the spatially resolved investigation of the stationary distribution of the optically-induced excess carriers. The n-i-p-i doping superlattice exhibited an extremely large ambipolar diffusion coefficient in the range of 104cm2s−1. The ambipolar diffusion coefficient of the n-i-p and n-i-p-i structure was demonstrated not to be a constant but a function of the charge carrier density. This strongly affects the spatial distribution of the excess carriers especially in the large signal regime (density of photo-generated carriers much larger than dark carrier concentration). The spatial distribution of the carriers in the small as well as in the large signal case can be understood theoretically if the real dependence of the ambipolar diffusion coefficient on the carrier density is taken into account. 相似文献
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Herbert Heinrich Brömer 《Zeitschrift für Physik A Hadrons and Nuclei》1960,158(2):133-141
The intensity decay of negative bands of N 2 + and of first positive bands of N2 in the auroral afterglow has been measured. An explanation, seeming possible for the decay curves of the first ones is proposed. By this the intensity decay in the beginning of the afterglow at high ionic densities is determined by the recombination of N 2 + with electrons. Later, the ambipolar diffusion of the charge carriers to the wall causes the time dependance. A value of the ambipolar diffusion coefficient in nitrogen, derived from the measurements is given by the relationD a ·p ≈ 124cm2 sec?1 Torr. The temperature of the charge carriers is estimated to be 313? K. The intensity decay of the pos. group in the afterglow seems mainly to be due to the diffusion of metastable particles to the wall. 相似文献
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发展了一种时-空分辨圆偏振光抽运-探测光谱及其理论,并用于本征GaAs量子阱中电子自旋扩散输运的实验研究.获得室温下本征GaAs量子阱中的“自旋双极扩散系数”为Das=37.5±15 cm2/s.此结果比用自旋光栅法测量到的掺杂GaAs量子阱中电子自旋扩散系数小.解释为是由于“空穴库仑拖曳”效应减慢了电子自旋波包的扩散输运.
关键词:
时-空分辨抽运-探测光谱
电子自旋扩散
GaAs量子阱 相似文献
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《Applied physics. B, Lasers and optics》1976,10(1):33-39
Investigations on the ambipolar diffusion of an electron-hole plasma transverse to a magnetic field have been carried out
in InSb. A plasma layer, produced at the surface of the sample by a short laser pulse, was moved through the sample in crossed
electric and magnetic fields by the Lorentz force. From the broadening of the plasma layer we found at 80K an enhanced diffusion
coefficient which decreased proportional to 1/B for magnetic fields higher than 1T, constrary to the expected classical 1/B
2 dependence. Furthermore, the diffusion coefficient was strongly dependent on the electric field. The ambipolar drift velocity,
measured simultaneously showed a classical behaviour. Together with the enhanced diffusion we observed instabilites in the
electric potential. The instability threshold decreased towards the cathode. 相似文献
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Measurements are reported of ambipolar diffusion coefficients as determined from ion density loss rates, and of electron temperatures determined using the single Langmuir probe technique, in afterglow plasmas of spectroscopically pure neon, argon and krypton. In each gas there was a critical pressure,p 0 c , above which the product of the ambipolar diffusion coefficient,D a , and the reduced gas pressure,p 0, was pressure independent and above which the electron temperature was found to cool asymptotically to the gas temperature. For pressures belowp 0 c ,D a p 0 decreased with decreasing pressure, and the electron temperature cooled asymptotically to a steady equilibrium value,T eq, below the gas temperature, this equilibrium value itself decreasing with decreasing gas pressure. These results clearly show that diffusion cooling of electrons was taking place at these low gas pressures. A detailed study of the krypton afterglow showed that the values ofD a p 0 andT eq for a given gas pressure were related in a manner predicted by simple diffusion theory. During the course of these measurements values for the zero field mobilities of Ne+, Ar+ and Kr+ ions in their parent gases were obtained and are also reported. 相似文献
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G. Waidmann 《Zeitschrift für Physik A Hadrons and Nuclei》1967,198(5):548-558
The time dependence of the electron density in the afterglow period of an electrodeless discharge in hydrogen was measured by means of 4- and 8-mm microwave interferometry. An exponential decay was observed in the late afterglow permitting the evaluation of a time constant in the density range from 1012–1010 electrons per cm3. The decay time of the plasma was influenced by the discharge conditions. Electron losses could be explained by ambipolar diffusion and attachment to impurities. Two diffusion coefficients were found correlated to the discharge duration. The mobility value H0=10.1±1.0 cm2/V · sec calculated from the diffusion coefficient found for short discharge pulses agrees with Saporoschenkos mobility value μ0=10.2 cm2/V · sec for the H 3 + -ion. A second mobility value μ0=14.8±1.2cm2/V · sec found for longer discharge pulses might refer to the H+-ion. 相似文献
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The chemical diffusion coefficient of Cu2O has been obtained for an oxygen partial pressure near 5 10?4 atm as a function of the temperature in the range 700–900°C D? = 1 62 10?4 exp(?5140 ± 600 cal mol ?1)/RT cm2s?1 This was easily achieved according to the electrochemical method used for the preparation of gaseous mixtures whose Po2; is lower than 10?5 atm The slight difference observed with the previously published results by Maluenda, and obtained for Po2 values which increase with T between 10?4 and 0.21 atm, may be due to an oxygen partial pressure effect already observed in the case of CoO. An ambipolar treatment of the chemical diffusion, in the case of p-type semiconductor MaOb, oxides, has allowed us to express the chemical diffusion coefficient as a function of the concentration of the prevailing defects and of their diffusion coefficient In the case where the prevailing defects are cationic vacancies α times ionized we have shown that the expression D? = (1 + α)Dvα can be generalized to the A2O compounds This set of results has allowed us, according to the copper self diffusion data obtained recently by Peterson etal, to estimate the apparent enthalpy of formation of the catiomc vacancies ΔHf 23 ± 0 8 kcal mol?1. 相似文献