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1.
The cathodoluminescence (CL) from indented Fe doped MgO single crystals has been studied with the scanning electron microscope and the results have been compared with the CL from undoped crystals. As in the undoped crystals, the iron doped crystals show in the deformed regions an enhanced luminescence emission but it has been found that iron acts as a quencher of luminescence. The results indicate that in the blue emission of the deformed crystals there is not a noticeable contribution of iron. From the evolution of CL with the irradiation time in the electron microscope it is concluded that the total Fe content influences the CL emission more than the Fe3+ content. 相似文献
2.
M. Herrera-Zaldívar P. Fernández J. Piqueras V.V. Sukhoveyev V.A. Ivantsov Y.G. Shreter 《Applied Physics A: Materials Science & Processing》2000,71(1):55-58
Cathodoluminescence (CL) in the scanning electron microscope has been applied to study the luminescence emission of GaN single crystals grown by LPE methods. CL spectra show the presence of near band edge and of yellow emissions. The latter has been found to be mainly related to rows of hillocks formed at the growth steps. The origin of the yellow luminescence is discussed 相似文献
3.
表面等离激元以其独特的光学性质广泛应用于纳米尺度的局域电磁场增强、超高分辨成像及微弱光电探测.阴极荧光是电子与物质相互作用而产生的光学响应,利用电子束激发金属纳米结构能够实现局域等离激元共振,并在亚波长尺度实现对共振模式的调控,具有超高空间分辨的成像特点.阴极荧光探测通常结合扫描电子显微镜或透射电子显微镜而实现,目前己被应用于表面等离激元的探测及共振模式的分析.本文从阴极荧光物理机理出发,综述了单一金属纳米结构和金属耦合结构的等离激元共振模式阴极荧光研究进展,并总结了阴极荧光与角分辨、时间分辨以及电子能量损失谱等关键技术相结合的应用,进一步分析了其面临的关键问题,最后展望了阴极荧光等离激元研究方向. 相似文献
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P. S. Vergeles N. M. Shmidt E. B. Yakimov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(6):890-893
The influence of irradiation in a scanning electron microscope on the optical properties inherent to light-emitting diodes (LEDs) with multiple InGaN/GaN quantum wells, assembled by means of the flip-chip mounting technique, has been investigated via the cathodoluminescence (CL) and electron-beam-induced current methods. It is demonstrated that the action of an electron beam qualitatively varies both these LEDs and structures with a thin upper GaN layer only at large beam energies. It has been revealed that irradiation not only leads to changes in the spectrum and intensity of CL but also decreases the energy corresponding to the excitation of emission associated with quantum wells. A similar effect is also observed in structures whose external quantum efficiency has been decreased several times due to long-running tests performed at an injection current density of 35 A/cm2 and a temperature of 100°C. 相似文献
6.
C. Díaz-Guerra A. Mitric J. Piqueras T. Duffar 《Superlattices and Microstructures》2009,45(4-5):407-412
Cathodoluminescence (CL) in the scanning electron microscope and wavelength dispersive X-ray microanalysis (WDX) have been used to assess the homogeneity of a whole Te-doped InxGa1?xSb ingot grown by the vertical Bridgman method under an alternating magnetic field. In particular, WDX has been used to determine the chemical composition of the ingot along the growth axis and several radial directions, while CL has been used to investigate the effective incorporation of In into the alloy, the nature and distribution of extended defects influencing the luminescence of the material and the shape evolution of the growth interfaces along the growth axis. CL spectroscopy reveals that doping with Te influences the band gap energy of this ternary compound through the Moss–Burstein effect. 相似文献
7.
Danielle K. Silletti Sarah A. Brokus Elly B. Earlywine Joshua D. Borycz Graham F. Peaslee Paul A. DeYoung Nickie J. Peters J. David Robertson JoAnn Buscaglia 《Radiation measurements》2012,47(3):195-200
At ambient temperatures, a permanent change due to neutron irradiation has been identified in the luminescent properties of the common mineral calcite. Calcite is one of many ubiquitous minerals that are known to exhibit luminescence under electron bombardment, a process known as cathodoluminescence (CL). The UV–Visible spectra of individual calcite grains were measured with CL spectroscopy before and after neutron irradiation. Exposure to neutrons causes additional crystal lattice defects (beyond those naturally-occurring) that leave a permanent, readily-measurable CL signature in the 515 nm region of the spectrum. Dose response results following irradiation have been measured and a spectroscopic signature is described that increases proportionately to neutron dose. The CL measurements are complicated by a dependence on the orientation relative to direction of excitation. When taken into account, the total dose to the crystal can be estimated, and possibly even the direction of the neutron source can be determined. This signature could potentially be developed into a nuclear forensics tool to help identify locations where special nuclear materials have been stored. 相似文献
8.
Stevens-Kalceff MA 《Physical review letters》2000,84(14):3137-3140
The first direct in situ observations of the production and microsegregation of radiolytic interstitial oxygen resulting from electron beam irradiation of crystal and amorphous oxygen deficient SiO2 polymorphs has been made using cathodoluminescence (CL) microanalysis (spectroscopy and microscopy). Previously unreported near-infrared CL emission is observed at 0.968+/-0.003 eV from crystal alpha-SiO2 (quartz) and at 0.971+/-0.003 eV from amorphous a-SiO2 (fused quartz and silica glasses) at 290 K. The energy and width of the near-infrared CL emission from electron-irradiated alpha-SiO2 polymorphs is consistent with the O2 (1)Delta(g)-->(3)Sigma(-)(g) transition associated with molecular oxygen. 相似文献
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Scattering behaviours to the two-dimensional electron gasinduced by the Al composition fluctuation in AlxGa1-xNbarrier in AlxGa1-xN/GaN heterostructures 下载免费PDF全文
<正>This paper reports that cathodoluminescence(CL) measurements have been done to study the alloy fluctuation of the Al0.3Ga0.7N layer in Al0.3Ga0.7N/GaN heterostructures.The CL images and linescanning results demonstrate the existence of compositional fluctuation of Al in the Al0.3Ga0.7N barrier.A model using aδ-shape perturbation Hamilton function has been proposed to simulate the scattering probability of the two dimensional electron gases (2DEG) induced by Al composition fluctuation.Two factors,including conduction band fluctuation and polarization electric field variation,induced by the Al composition fluctuation have been taken into account.The scattering relaxation time induced by both factors has been estimated to be 0.31 ns and 0.0078 ns,respectively,indicating that the variation of the piezoelectric field is dominant in the scattering of the 2DEG induced by Al fluctuation. 相似文献
11.
Nanostructures of two transition metal oxides, WO3 and α-Fe2O3, have been grown by a thermal deposition method without a catalyst and characterized by x-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy and cathodoluminescence (CL) in the SEM. WO3 micro and nanorods exhibit CL emission two orders of magnitude higher than CL intensity from the untreated oxide. α-Fe2O3 nanostructures with different morphologies (wires, belts, rods, urchins) were grown at different temperatures on Fe substrates. CL spectra of these nanostructures show emission bands related to charge transfer and ligand field transitions. 相似文献
12.
We have obtained intense cathodoluminescence (CL) emission from electron beam modified porous silicon films by excitation with electrons with kinetic energies below 2 keV. Two types of CL emissions were observed, a stable one and a non-stable one. The first type is obtained in well-oxidized samples and is characterized by a spectral peak that is red shifted with respect to the photoluminescence (PL) peak. The physically interesting and technologically promising CL is however the CL that correlates closely with the PL. Tuning of this CL emission was achieved by controlling the average size of the nanostructure thus showing that the origin of this CL emission is associated with the quantum confinement and the surface chemistry effects that are known to exist in the porous silicon system. We also found that the electron bombardment causes microscale morphological modifications of the films, but the nanoscale features appear to be unchanged. The structural changes are manifested by the increase in the density of the nanoparticles which explains the significant enhancement of the PL that follows the electron irradiation. 相似文献
13.
Mariusz Pluska Andrzej CzerwinskiJacek Ratajczak Anna SzerlingJerzy Kątcki 《Physica B: Condensed Matter》2012,407(15):2854-2857
Cathodoluminescence (CL) in scanning electron microscopy (SEM) is commonly accepted as revealing local properties of a specimen region illuminated by an electron beam. CL is widely used to visualize defects in semiconductor structures. However, the presence of a strong electric field in, for example, heterojunctions or p–n junctions causes a separation of generated electron–hole (e–h) pairs and suppresses recombination in the specimen region excited by the beam. As a result CL – a radiative recombination – becomes quenched. At the same time, electron beam-induced current (EBIC) flows throughout the structure, which may produce secondary electroluminescence that is registered by the CL detector. Consequently, the CL measurement is distorted and if there are defects in the structure, they remain unrevealed. The current study shows that registration of the CL signal for different values of electron beam current (including high ones) enables true defect detection in semiconductor layers with built-in electric field. Results for a special test structure prepared with focused ion beam on AlGaAs/GaAs laser heterostructures with an 8 nm InGaAs quantum well are presented. 相似文献
14.
C. Díaz-Guerra J. Piqueras Y.Y. Tomashpolsky N.V. Sadovskaya 《Applied Physics A: Materials Science & Processing》1997,64(4):361-366
2 Sr2CaCu2O8+x superconducting ceramics have been irradiated in the scanning electron microscope (SEM), and the irradiation-induced effects
investigated by cathodoluminescence (CL), secondary electron emission (SEE) and X-ray microanalysis. Electron beam irradiation
causes a slight Bi depletion and an inhomogeneous Ca distribution. A higher CL intensity emission is found in the irradiated
areas, where besides an enhancement of the oxygen content related 2. 4 eV band, another CL bands probably related to new non-superconducting
phases induced by irradiation can be observed. SEE yield measurements allow to detect an oxygen depleted region surrounding
the irradiated areas. X-ray microanalysis shows that this intermediate region retains the cationic composition of the unaffected
material. CL spectra from bright zones inside the same area also show a dominant 2. 4 eV emission band, which supports its
relation with oxygen deficiency or rearrangement in high- superconductors.
Received: 30 July 1996/Accepted: 8 October
1996 相似文献
15.
研究了36种有机化合物对鲁米诺-高碘酸钾-过氧化氢(luminol-KIO4-H2O2)体系化学发光的影响,发现其大部分能抑制或增强体系化学发光强度,并且抑制或增强化学发光强度的能力与化学发光体系的pH值以及有机化合物分子结构中芳香环上功能基(—OH和—NH2)的数目、位置,取代基的电子效应、空间效应等有关。讨论了化学发光强度抑制或增强的机理。基于24种有机化合物对体系化学发光的抑制或增强考察了其分析应用的可能性,发现数个化合物的检测限可达ng·mL-1水平。 相似文献
16.
J. Ma Rincón P. Fernández J. Llopis 《Applied Physics A: Materials Science & Processing》1987,44(4):299-303
Characterization of mullite-ZrO2 ceramics by Cathodoluminescence (CL) technique has been made. The analyses of the CL emission show complex spectra with broad and sharp bands. An attempt has been carried out to relate these bands to the main constitutive phases in the samples. Spatial distribution of the CL is found to be inhomogeneous. 相似文献
17.
M. M. Mikhailov 《Journal of Applied Spectroscopy》2006,73(1):79-84
The diffuse reflectance (DR) spectra and the cathodoluminescence (CL) spectra in the range 0.34–2.10 μm and changes in the
spectra after bombardment by accelerated electrons have been studied as a function of the specific surface area and the grain
sizes of titanium dioxide (rutile) powders of different grades (P1, P2, P02, R10). It has been established that the diffuse
reflection coefficient and the luminescence band intensity increase as the specific surface area decreases and the grain size
of the powder increases. A smaller specific surface area of the powders means lesser initial flareup and subsequent “quenching”
of the CL bands as a function of electron fluence. It has been shown that history-related differences between powders of different
grades is a less significant factor than the specific surface area in determining the diffuse reflectance and luminescence
and also the radiation resistance of the powders.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 73–77, January–February, 2006. 相似文献
18.
Phyllis J. Fisher William S. Wessels Franklyn G. Prendergast 《Optics Communications》2008,281(7):1901-1908
We have combined the specificity of antibody labeling, the power of fluorescence detection, and the resolution of scanning electron microscopy (SEM) to identify antigenic sites on nanometer-scale features of mammalian cells. Cathodoluminescence (CL) detection in SEM was used to locate fluorophores bound to antibodies specific for cell surface epitopes. Sample preparation and instrument setup were optimized to yield the maximum luminescence compatible with a high definition secondary electron image. Separable CL component distances of less than 300 nm have been calculated. Antibody-specific fluorophores are associated with unique morphological features on a human dendritic cell. This technology provides a tool to identify the relationship between cell surface structures and receptor-ligand binding or other antigen-defined physiological states. 相似文献
19.
Cathodoluminescence (CL) measurements have been performed to characterize defects in InP created by reactive ion etching (RIE) in a CH4/H2/Ar plasma. Etching of semi-insulating InP:Fe leads to an increase of CL intensity. After etching of undoped, n-type InP a reduction of band-edge as well as band-acceptor/donor-acceptor-pair emission intensity is detected. No additional emission lines due to etching-induced defects have been detected in the spectral range examined. After a few minutes of electron beam injection the band-edge luminescence recovers to its initial value. Using donor-bound exciton emission, which is especially affected by RIE, mapping of these defects is possible, showing homogeneous defect distribution. In conjunction with other measurements (conductivity, photoluminescence, electron-beam-induced current, Raman scattering, Auger electron spectroscopy depth profiling) these results indicate a nonradiative, donor-like defect created by RIE. 相似文献
20.
Oxidizing anneals have been carried out to test the stability of nickel precipitates previously formed in MgO:Ni by thermochemical reduction. The annealed crystals have been examined by transmission electron microscopy (TEM) and cathodoluminescence (CL). Both techniques, TEM and CL, reveal that the nickel precipitates become unstable under oxidizing annealing at temperatures 1223 K for 30 min. Cathodoluminescence results are analyzed on the basis of anion vacancy complexes and Ni2+ transitions. 相似文献