共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Prucnal L. Rebohle A.N. Nazarov I.N. Osiyuk I.P. Tjagulskii W. Skorupa 《Applied physics. B, Lasers and optics》2008,91(1):123-126
Charge trapping and quenching of electroluminescence (EL) in SiO2 layers implanted by Ge and rare earth (RE) ions during hot electron injection were investigated. In case of the SiO2:Ge layer the EL quenching is caused by the transformation of the luminescent defects (Ge–Si or Ge–Ge) to optically inactive centers during hot electron excitation, whereas the EL from rare earth centers is quenched due to
the electron trapping by RE-centers or their surroundings, but not due to their optical deactivation. Therefore, the flash
lamp post-injection annealing releasing trapped electrons reactivates RE centers and increases the operating time of metal–oxide–silicon
light emitting devices (MOSLEDs).
PACS 72.20.Jv; 73.40.Qv; 73.50.Gr 相似文献
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Raman spectroscopy was used for rapid in-situ measurement of alcohols in ethanol-methanol-water ternary systems. Mass fractions of the individual components were determined using calibration curves for binary systems of ethanol-water, methanol-water, and ethanol-methanol. Calibration curves were constructed by calculating the ratio of the Raman peak intensity of a component and that of an external standard (acetonitrile). Assuming additivity of the spectra, simultaneous equations were written, and mass fractions of ethanol, methanol, and water in the ternary solutions were determined by solving the system of equations through calculating an inverse matrix. The relative errors between the mass fractions obtained from the Raman spectra and those obtained from mass measurements were <0.6%. 相似文献
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V. L. Vaks A. N. Panin S. A. Basov A. V. Illyuk S. I. Pripolzin D. G. Peveliev Yu. I. Koshurinov 《Radiophysics and Quantum Electronics》2009,52(7):511-517
We develop the principles of construction of a gas spectrometer based on nonstationary effects (freely decaying polarization,
fast sweep, etc.) with the use of solid-state devices in the terahertz frequency band. A spectrometer based on quantum semiconductor
superlattices (QSSLs), which is operated at up to 2.5 THz and meets the requirements of high and ultra-high resolution spectroscopy
is implemented. As the radiation source in this spectrometer, we use a frequency synthesizer which was developed by the authors
of this paper. The device is based on a phase-shift keyed Gunn oscillator and a QSSL frequency multiplier. As the receiving
system, a QSSL mixer operated in harmonic mode was employed. The possibilities of harmonic generation by using the radiation
of a spectrally pure Gunn oscillator and a QSSL frequency multiplier are studied with the help of the IR Fourier spectrometer
“BOMEM” DA3.002 with Si-composite bolometer operated at a temperature of 4.2 K. The 45th harmonic at a frequency of about
6.5 THz was reached in the experiment. The spectral absorption lines of NH3 and CO at 2400017.632 and 1841345.506 MHz, respectively,
were measured. 相似文献
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Mallar Ray Kakali Jana N.R. Bandyopadhyay S.M. Hossain Daniel Navarro-Urrios P.P. Chattyopadhyay Martin A. Green 《Solid State Communications》2009,149(9-10):352-356
We report room temperature visible photoluminescence (PL), detectable by the unaided eye, from colloidal suspension of silicon nanocrystals (nc-Si) prepared by mechanical milling followed by chemical oxidation. The PL bands for samples prepared from Si wafer and Si powder peak at 3.11 and 2.93 eV respectively, under UV excitation, and exhibit a very fast (~ns) PL decay. Invasive oxidation during chemical treatment reduces the size of the nc-Si domains distributed within the amorphous SiO2 matrix. It is proposed that defects at the interface between nc-Si and amorphous SiO2 act as the potential emission centers. The origin of blue–violet PL is discussed in relation to the oxide related surface states, non-stoichiometric suboxides, surface species and other defect related states. 相似文献
7.
Photoelectric characteristics of silicon P–N junction with nanopillar texture:Analysis of X-ray photoelectron spectroscopy
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Silicon nanopillars are fabricated by inductively coupled plasma(ICP) dry etching with the cesium chloride(CsCl)islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus(P) diffusion by liquid dopant source(POCl3) at 870℃ to form P–N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy(XPS) is used to measure the Si 2p core levels of P–N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P–N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light.The energy shift of the Si 2p core level is-0.27 eV for the planar P–N junction and-0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one. 相似文献
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The formation and growth of titanium dioxide nanoparticles in two-dimensional, non-premixed methane–air flames is investigated
via direct numerical simulation. The simulations are performed by capturing the spatio-temporal evolution of the fluid, chemical,
and particle fields. The fluid is described by the conservation of mass, momentum, and energy equations; species transport
is augmented by the effects of methane–air combustion and the oxidation of titanium tetrachloride; and a nodal approximation
to the general dynamic equation is used to represent the effects of nucleation, condensation and coagulation. Simulations
are performed for two initial reactant concentration levels, 20% and 30% titanium tetrachloride by mass. The evolution of
the temperature, chemical and particle fields as a function of space and size are presented. Results indicate that particle
formation and growth is mixing limited in this study and the mean particle diameter and geometric standard deviation increase
as the concentration level of the initial reactants increases. In general, high geometric standard deviations correspond to
a large particle sizes. 相似文献
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Ipsocentric calculations of current density at the B3LYP/6-311++G(2d,2p) level show that the planar Si6 ring supports a diatropic π ring current of about half the strength of the equivalent π current in benzene, both in the presumed global optimum geometry of Si6Li6 and in geometries occupying higher-energy local minima, corroborating the attribution of aromaticity to this silicon analogue of benzene. 相似文献
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The effect of changes in laser-induced stress upon irradiation of monocrystalline silicon was studied in detail using Mach–Zehnder interferometer, high speed camera and computer processing system, real-time detection of stress distribution and stress evolvement under different laser fluences and pulse widths. After irradiation, the changes of interference fringes were used to calculate the stress value. The results show that the stresses increased with the increase of the laser fluence. The formation of stress could be explained using thermoelastic theory. The cleavage plane’s dislocation appears in the following sequence: (1 1 1) plane appears and then the dislocation slip of (1 1 0) cleavage plane appears. In addition, it is found that cleavage plane of (1 1 1) mainly exist in the spot and cleavage plane of (1 1 0) mainly exists in the vicinity of spot radius. Stress areas mainly exist in the thin layer on the surface of silicon. Furthermore, stress field was analysed by the finite-element method to get a better understanding of the formation and distribution of stress. Under the same experimental conditions, the numerical results are in agreement with the experimental values. 相似文献
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Silicon p–i–n diodes with different i-region widths are fabricated and tested. It is found that the current shows the non-monotonic behavior as a function of i-region width at a bias voltage of 1.0 V. In this paper, an analytical model is presented to explain the non-monotonic behavior, which mainly takes into account the diffusion current and recombination current contributing to the total current. The calculation results indicate that the concentration ratio of p-region to n-region plays a crucial role in the non-monotonic behavior, and the carrier lifetime also has a great influence on this abnormal phenomenon. 相似文献
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K. Suzuki Y. Yoshida K. Hayakawa K. Yukihira M. Ichino K. Asahi 《Hyperfine Interactions》2010,195(1-3):213-217
In the present work, the formation of the Al70Cu20Fe10 icosahedral phase by mechanical alloying the elemental powders in a high-energy planetary mill was investigated by X-ray diffraction and Mössbauer spectroscopy. It was verified that the sample milled for 80 h produces an icosahedral phase besides Al(Cu, Fe) solid solution (β-phase) and Al2Cu intermetallic phase. The Mössbauer spectrum for this sample was fitted with a distribution of quadrupole splitting, a doublet and a sextet, revealing the presence of the icosahedral phase, β-phase and α-Fe, respectively. This compound is not a good hydrogen storage. The results of the X-ray diffraction and Mössbauer spectroscopy of the sample milled for 40 h and annealed at 623°C for 16 h shows essentially single i-phase and tetragonal Al7Cu2 Fe phase. 相似文献
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Alfadhl Yahya Khaled Siti Khairunniza Bejo Nazmi Mat Nawi Idris Abu Seman Daniel Iroemeha Onwude 《应用光谱学评论》2018,53(1):36-64
Plant diseases can greatly affect the total production of food and agricultural materials, which may lead to high amount of losses in terms of quality, quantity and also in economic sense. To reduce the losses due to plant diseases, early diseases detection either based on a visual inspection or laboratory tests are widely employed. However, these techniques are labor-intensive and time consuming. In a view to overcome the shortcoming of these conventional approaches, several researchers have developed non-invasive techniques. Recently, spectroscopy technique has become one of the most available non-invasive methods utilized in detecting plant diseases. However, most of the studies on the application of this novel technology are still in the experimental stages, and are carried out in isolation with no comprehensive information on the most suitable approach. This problem could affect the advancement and commercialization of spectroscopy technology in early plant disease detection. Here, we review the applications and limitations of spectroscopy techniques (visible/infrared, electrical impedance and fluorescence spectroscopy) in early detection of plant disease. Particular emphasis was given to different spectral level, challenges and future outlook. 相似文献
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In this paper, blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have been elucidated, with a focus on the degradation characteristics of the emission layer (EML). The operational stability against electrical stress was investigated for two host materials and four doping concentrations, which were used as the EML. The operating stability of the devices was confirmed by comparing the peak capacitance before and after degradation. Devices using bis [2-(diphenyl-phosphino) phenyl] ether oxide (DPEPO) as a host exhibited poor degradation characteristics. However, high stability was confirmed when 3,3-di (9H-carba-zol-9-yl)-biphenyl (mCBP) was used. DPEPO host devices are most resistant against performance degradation when they are doped with 10 wt% 10,10'-(4,4′-sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine (DMAC-DPS). We successfully determined the electroluminescence characteristics of the device depending on the host material, as well as the doping concentration, using the capacitance–voltage method. 相似文献
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One of the key aspects regarding the technological development of nuclear fusion reactors is the understanding of the interaction between high-energy ions coming from the confined plasma and the materials that the plasma-facing components are made of. Among the multiple issues important to plasma–wall interactions in fusion devices, physical erosion and composition changes induced by energetic particle bombardment are considered critical due to possible material flaking, changes to surface roughness, impurity transport and the alteration of physicochemical properties of the near surface region due to phenomena such as redeposition or implantation. A Monte Carlo code named MATILDA (Modeling of Atomic Transport in Layered Dynamic Arrays) has been developed over the years to study phenomena related to ion beam bombardment such as erosion rate, composition changes, interphase mixing and material redeposition, which are relevant issues to plasma-aided manufacturing of microelectronics, components on object exposed to intense solar wind, fusion reactor technology and other important industrial fields. In the present work, the code is applied to study three cases of plasma material interactions relevant to fusion devices in order to highlight the code’s capabilities: (1) the Be redeposition process on the ITER divertor, (2) physical erosion enhancement in castellated surfaces and (3) damage to multilayer mirrors used on EUV diagnostics in fusion devices due to particle bombardment. 相似文献
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Shinho Kim Chansu Park Jung-Chul Lee Jun-Sik Cho Yangdo Kim 《Current Applied Physics》2013,13(3):457-460
Hydrogenated microcrystalline silicon germanium (μc-Si1?xGex:H) films were investigated as a bottom cell absorber in multi-junction solar cells. μc-Si1?xGex:H films were prepared using very high frequency (VHF, 60 MHz) plasma enhanced chemical vapor deposition (PECVD) systems working pressure of about 1.5 Torr. The precursor flow rates were carefully controlled to determine the phase transition point and to improve the crystallinity of μc-Si1?xGex:H. A relatively high plasma power was necessary to have the high hydrogen (H2) dilution. Raman spectroscopy study showed transition steps from amorphous to microstructure morphology as hydrogen dilution increasing. Crystallite Si–Ge and Ge–Ge bonds were occurred at relatively higher H2 dilution compare to crystallite Si–Si bond. The rapidly increased Ge content as increasing the H2 dilution is believed mainly due to the different decomposition rate of silane (SiH4) and germane (GeH4). The other reason of high Ge content even at the low GeH4 precursor flow rate is probably due to the preferential etching of silicon atom by H2. The preferential etching of Si–H possibly occurred in very highly concentrated H2 plasma due to the preferential attachment of Si–H. The compositions of μc-Si1?xGex:H films measured using RBS were Si0.83Ge0.17, Si0.67Ge0.33 and Si0.59Ge0.41 at H2/SiH4 flow rate of 60, 80 and 100, respectively. μc-Si1?xGex:H films showed the dark (σd) and photo conductivity (σp) of about 10?7 and 10?5 S/cm, respectively and photo response (σp/σd) was about 102. This study will present the comprehensive evaluation of crystallization behavior of μc-Si1?xGex:H films. 相似文献
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Shallow donors in silicon related to nitrogen–oxygen complexes have been investigated by piezospectroscopy of their hydrogenic transitions in the far infrared. Complete stress dependences up to 0.25 GPa were obtained for the 1s→2p0 and 1s→2p± transitions of the most prominent members of the (N, O)-family, N–O-3 and N–O-5. Very unusual for shallow donors in silicon, the symmetry of the ground state wave function is T2-like. The lifting of orientational degeneracy for stress in the 〈1 0 0〉, 〈1 1 1〉, and 〈1 1 0〉 directions is compatible with a C2v defect symmetry. Data from the other species of the (N, O)-family are indicative for the same symmetry. The microscopic structure of these centers, in part contradictory to present theoretical models, is discussed. 相似文献