共查询到20条相似文献,搜索用时 31 毫秒
1.
利用MgF2作为扩散源进行镁离子内扩散LiNO3单晶基片的研究.经电子探针显微镜分析表明,镁的扩散层镁离子浓度分布具有近似半抛物形和阶跃形分布,并得到镁的激活能为104KJ/mol.X射线衍射分析发现,当镁离子内扩散超过一定程度时,在镁的扩散层出现具有LiNb3O8的物相结构,并发现该物相结构的出现与LiNO3体内锂离子的外扩散和扩散表面氟离子的存在有关.由扫描电子显微镜观察到氟离子以LiF的形式出现,并随着扩散程度的增大,挥发和脱离开扩散层表面.
关键词: 相似文献
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The microstructure deformation of a diffused surface occuring between the first and second exposures causes a decrease of visibility in holographic interference of equal inclination. This phenomenon is analyzed, and its applications to the evaluation of a small deformation in the diffused surface and to a fatigue test are suggested. 相似文献
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通过扫描电子显微镜观察到刚性光纤元器件芯、皮玻璃之间有扩散层,用干涉仪测量了扩散层的折射率范围。本文从玻璃网络结构观点解释了这一扩散机理,并就刚性光纤元器件芯、皮玻璃配方设计中如何使离子扩散减到最小程度提出了可行性措施。 相似文献
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B.K. Meyer J. Stehr A. Hofstaetter N. Volbers A. Zeuner J. Sann 《Applied Physics A: Materials Science & Processing》2007,88(1):119-123
Diffusion of Li, Na and K into single-crystal substrates of ZnO was performed. We compare the results with ZnO epitaxial films
doped with the respective elements during growth. The diffused and in-situ doped layers were studied using mass spectroscopy
and low temperature photoluminescence spectroscopy. Li and Na are known to produce deep acceptor centers which give rise to
shallow donor to deep acceptor recombinations in the visible spectral region. We will demonstrate that shallow acceptors are
also introduced, having binding energies around 300 meV. A donor–acceptor pair recombination (zero phonon line at 3.05 eV)
with LO phonon replica is observed. We further investigated bulk ZnO crystals which contained the deep Li acceptor by thermal
treatments under H2 atmospheres. With increasing annealing temperature shallow donors are introduced as monitored by EPR while the EPR signal
of the neutral Li acceptors decreases. Quite unexpectedly, the shallow Li acceptor centre which is not present in the as-grown
state is also created.
PACS 71.55.Gs; 78.55.Et; 76.30.Da 相似文献
6.
Ag or Au was deposited on a clean Si substrate at room temperature. These systems, Ag/Si and Au/Si, were annealed at various temperatures or various heating times. Due to the annealing, Ag or Au diffused into Si and/or Si diffused into the metal. The changes of the surface composition are analyzed by a quantitative Auger Electron Spectroscopy (AES) method which is newly developed as a non-destructive method. In the case of Ag/Si, Ag migrated into the Si substrate and/or Si diffused into Ag. Then, Ag-Si solid solution was produced. After the annealing, the Ag/Si system is changed into Ag/(Ag-Si)/Si of the three-phase structure. In the case of Au/Si (Au film thickness < 15 Å), the Au film thickness became thinner by annealing. The Au/Si system always keeps the Au/Si phase after annealing, while there was no Au-Si solution area. The difference between the Ag/(Ag-Si)/Si and the Au/Si structure is attributed to the reason that Au diffuses more quickly than Ag into the Si substrate. AES results after annealing cannot be explained by the model of the formation of the three-dimensional island structure which is commonly referenced. 相似文献
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气溶胶前向散射大气能见度测量系统传递系数的标定及校准方法 总被引:4,自引:0,他引:4
分析了气溶胶的前向角散射特性,利用标准的大气透射仪标定前向散射大气能见度测量系统的传递系数。当系统结构发生变化时,传递系数也随之改变,为保证系统测量的准确性和简化系统传递系数的标定过程,提出了一种利用标准漫透射板校准系统传递系数的方法。该方法使用了两块具有相同透射系数的漫透射板,使气溶胶粒子团在前向半球上产生漫散射,此时探测器的测量值即为包含了仪器常数的定值。当系统结构改变时,这个测量值相对于原测量值的变化率作为比例系数代入系统传递系数的计算,实现校准。 相似文献
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Using the hydrodynamical model, we have obtained the surface plasmon dispersion relation for spherical metallic particles
in the following two cases: (1) a sharp surface cut off in electron density and (2) a diffused electron density at the surface.
The diffused density is modelled with a step function. The diffuse nature of the electron density at surface of the metal
particle is necessary to understand the experimental result for particles with small radii. Shift in the absorption frequency
is estimated and found to be small. 相似文献
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用卢瑟福背散射/沟道技术研究了p-GaN上的Ni/Au电极在氧气氛下相同合金温度(500℃)不同合金时间后的微结构演化,以揭示欧姆接触的形成机制.利用背散射随机谱和RUMP模拟程序研究了电极金属之间的互扩散,用沟道谱探测了电极金属中的氧分布.结合不同合金时间下比接触电阻ρc的变化,发现随着合金时间的延长比接触电阻持续降低,在合金时间60 s后降低的速度减慢, Au扩散到GaN的表面,在p-GaN上形成外延结构,O向电极内部扩散反应生成NiO对降低ρ关键词:
GaN
卢瑟福背散射/沟道
欧姆接触 相似文献
11.
The uniform charge distribution inside a nucleus is re-examined by using a diffused charge distribution, which reduces to the uniform charge distribution when the thickness is taken to be zero. Electron radial wave functions and ft values of superallowed Fermi transitions are discussed in terms of these two different charge distributions. 相似文献
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A. Cheriet A. Keffous L. Guerbous Y. Belkacem M. Kechouane H. Menari 《Superlattices and Microstructures》2012
p-Type porous SiC layers were fabricated by anodization of resistive p-type 6H–SiC samples using HF/ethylene glycol solution. Thin films of lithium (Li) and aluminum (Al) as donor and acceptor elements were vacuum deposited and diffused onto SiC substrates prior to anodization. The aim of this work is to investigate the properties of the nanoporous SiC layer formed by this method and to deduce the effect of diffused lithium as donor and Al as acceptor atoms on their photoluminescence response (PL). The profile distribution of lithium and aluminum diffused atoms was carried out using secondary ion mass spectrometry (SIMS). The photoluminescence spectra of the anodized Al-diffused samples exhibit a broad emission band centered at about 475 nm, while the Li-diffused samples exhibit luminescence with one broad peak located at 655 nm, attributed to Li-related defect centers. In addition, the PL intensity of lithium diffused samples varies with varying the etching time. Finally, the results are expected to have important applications in modern optoelectronic devices and electrode materials of lithium batteries. 相似文献
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Perturbed angular correlation of gamma rays (PAC) is applied to study the atomic structure of grain boundaries (gb) in fcc metals using nuclear quadrupole interactions.111In probes were diffused in samples of Au, Cu, Ni and Pt which had first been annealed to form high-angle gbs. Diffusions were carried out at such low temperatures that only gb diffusion should occur (Harrison's type-C kinetic regime), and measurements were made after removing any residual surface activity. For three Pt samples, a unique signal attributed to a gb site was detected with a site fraction of about 50%, coupling frequency 1=80.0(2) Mrad/s and electric-field-gradient asymmetry parameter =0. A Pt sample of 99.9995% purity exhibited much less inhomogeneous signal broadening than 99.998% pure samples, indicating the level of purity necessary to observe the gb sites via quadrupole interactions. The broadening is attributed to gb segregation. For Au, Cu and Ni, only ill-defined, non-unique signals were detected, apparently because of gb segregation. The small broadening in the high-purity Pt sample indicates a high degree of uniformity in the crystal structure of the high-angle gb sites. The large site fraction of the 80 Mrad/s signal demonstrates the dominance of a single site for Cd probes in high-angle gbs. 相似文献
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Yves Rezette 《Optics Communications》1977,22(1):22-25
With a reference beam diffused by a depolarizing diffuser, we reconstruct holographically the polarization form which existed at each object point. 相似文献
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I. Savatinova P. Simova L. Tsonev 《Applied Physics A: Materials Science & Processing》1979,20(3):219-224
It has been shown that the attenuation characteristics of TE modes in diffused waveguides are different from those of a conventional
slab. A simple semiempirical analysis is performed on the base of a ray-optics picture assuming a parabolic index distribution.
Analytical expressions for surface scattering and volume loss are derived. The analysis precisely describes the modal loss
behaviour of Ag+ ion-exchanged waveguides in glass (new results) and Nb diffused waveguides in LiTaO3 (data reported by other authors). 相似文献
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M. Meléndez-Lira I. Hernández-Calderón D. W. Niles H. Höchst 《Applied Physics A: Materials Science & Processing》1994,58(3):219-222
CdTe films have been grown on top of GaAs(100) by means of Molecular Beam Epitaxy (MBE) at 300 °C substrate temperature. Different procedures for the CdTe growth and for the preparation of the GaAs substrates resulted in diverse crystalline qualities of the CdTe films. We present the results obtained from PhotoReflectance (PR) measurements of these films employing HeNe and Ar-ion lasers as modulating excitation. For Ar excitation, the ratio of CdTe to GaAs signal strength for the E
0 transition is enhanced, allowing a differentiation of the contributions from film and substrate. Both the PR line shape and intensity are correlated to the structural quality of the CdTe films. One of the samples presented a below-band-gap transition of the GaAs substrate around 30±5 meV from E
0 which is attributed to donor states produced by Te atoms diffused in the interface; this result demonstrates the high sensitivity of the photoreflectance technique to the structural properties of interfaces. 相似文献
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早期声在厅堂中的分布 总被引:2,自引:0,他引:2
厅堂内早期反射声能分布与厅堂的容积、体形、吸声布置及接收点的位置等有关,其形成的早期声场与完全扩散声场有较大的差别。因而有关与早期反射声能相关的音质参量在厅堂中的分布情况无法用扩散场的理论来预计。本文通过对四个厅的测量结果,来分析早期反射声能在厅堂中分布的特性。 相似文献