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We report the experimental results of picosecond pulse laser microstructurlng (pulse duration 35 ps, wavelength 1.06μm, repetition rate 10 Hz) of silicon using the direct focusing technique. Arrays of sharp coldcal spikes located below the initial surface have been formed by cumulative picosecond pulsed laser irradiation of silicon in SF6. Irradiation of silicon surface in air, N2, or vacuum creates ripple-like patterns, but does not create the sharp conical spikes. 相似文献
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J. Frühauf E. Gärtner E. Jänsch 《Applied Physics A: Materials Science & Processing》1999,68(6):673-679
New shapes of silicon microelements which can be partially situated outside the wafer plane can be created by the combination
of wet anisotropic etching and plastic deformation at high temperatures. Therefore new applications become possible.
In order to characterize the plastic behaviour of the silicon microelements bending tests in the 3-point manner were carried
out at monocrystalline, differently orientated beams with variation of temperature, bending rate and maximum bending. Additionally
the fracture strength at room temperature of deformed and undeformed beams was determined. The dislocation content introduced
during the deformation was analysed by the etch pit technique.
The deformation is characterized by the formation of dislocations, a pronounced yield point effect, and an orientation-dependent
strengthening. The yield points depend strongly on temperature. Because of the strong dependence on the deformation parameters
it is possible to create the same amount of irreversible deformation at different stages of the stress–bend diagrams resulting
in different dislocation contents and therefore different properties. The analysis of the fracture strength values by means
of the Weibull statistics shows a slightly decreased average fracture strength of the deformed material in comparison to the
undeformed silicon but a strongly increased Weibull modulus.
Received: 22 September 1998 / Accepted: 29 January 1999 / Published online: 28 April 1999 相似文献
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M. Naddaf O. Mrad A. Al-zier 《Applied Physics A: Materials Science & Processing》2014,115(4):1345-1353
A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO–PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO–PS matrix exhibits an additional weak ‘blue’ PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO–PS matrix. 相似文献
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《声学学报:英文版》1999,(4)
lIntroductionIntheelectroaconsticequlmeatandsyStem,theelectroacousticdevices(suchasndcro-phone,loudspeakerl1])telephonetransedterandreceiver,etc,)playveryhaPortantrole.Thirperformancesandqualltygenerallydeterminthelevelofthewholeequlpmentandsystem.So,theresearchworkanddevelopndofelectroacousticdevicesareinterestedbyacousticiansincoIIUnwhcationwork.Atthe25thGermanAcousticsDAGACooferense,*heldinBerlinonMarch1999,severalgroupsreportedprogressincoDyertingthestandardelemelltsofandcro-phones.2… 相似文献
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For x rays the real part of the refractive index, dominated by Rayleigh scattering, is negative and converges to zero for higher energies. For γ rays a positive component, related to Delbrück scattering, increases with energy and becomes dominating. The deflection of a monochromatic γ beam due to refraction was measured by placing a Si wedge into a flat double crystal spectrometer. Data were obtained in an energy range from 0.18?MeV to 2?MeV. The data are compared to theory, taking into account elastic and inelastic Delbrück scattering as well as recent results on the energy dependence of the pair creation cross section. Probably a new field of γ optics with many new applications opens up. 相似文献
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Porous silicon (PS) light-emitting diode (LED) with an ITO/PS/p-Si/Al structure was fabricated by anodic oxidation method. Photoluminescence (PL) of the PS LED was measured with a peak at 593 nm, and electroluminescence (EL) was measured with a peak at 556 nm under the conditions of 7.5-V forward bias and 210-mA current intensity. The spectral width of EL was measured to be about 160 nm. 相似文献
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Jiahe Chen Deren Yang Xiangyang Ma Duanlin Que 《Applied Physics A: Materials Science & Processing》2009,94(4):905-910
The internal gettering (IG) effects involved with a rapid thermal anneal (RTA) in germanium-doped Czochralski silicon (GCz-Si)
wafer have been investigated. It was found that germanium doping could enhance the oxygen precipitation in bulk while shrinking
the denuded zone width near the surface through pre-RTA at high temperature plus low–high temperature conventional furnace
anneals. Rapid cooling rate after RTA was clarified to be beneficial for oxygen precipitation for GCz-Si wafer. It was suggested
that the germanium doping could increase the vacancy concentration in Cz-Si during RTA by forming the germanium–vacancy complexes.
In contrast to that in Cz-Si wafer, the smaller-sized higher-density oxygen precipitates were presented in the nucleation
anneals, then followed RTA pretreatment while more oxygen precipitates survived during ramping processes after nucleation
anneals in the GCz-Si wafer. Enhanced heterogeneous nucleation and reduced critical radius of precipitates associated with
the germanium–vacancy complexes have been proposed for the oxygen precipitation enhancement. 相似文献
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V. ?vr?ek T. Sasaki R. Katoh Y. Shimizu N. Koshizaki 《Applied physics. B, Lasers and optics》2009,94(1):133-139
Blue luminescent colloidal silicon nanocrystals (Si-ncs) were synthesized at room temperature by nanosecond pulsed laser ablation
of a single-crystal silicon target in de-ionized water. Irregular Si-nc fragments obtained by laser ablation are stabilized
into regularly shaped, spherical, and well-separated aggregates during the aging process in water. Aging in de-ionized water
for several weeks improved the photoluminescence (PL) intensity. At least two weeks of aging are necessary for observation
of broad blue room temperature PL with a maximum centered at 420 nm. Detailed structural analysis revealed that agglomerates
after aging for several months contain Si-ncs with irregular shape smaller than the quantum confinement limit (<5 nm). These
blue luminescent Si-ncs dispersed in de-ionized water exhibited a PL decay time of 6 ns, which is much faster than that of
Si-ncs prepared in traditional ways (usually on the order of microseconds). The oxidized Si-ncs with quantum confinement effects
are responsible for a PL band around 400 nm visible to the naked eye at room temperature. 相似文献
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Hydrogenated amorphous silicon (a-Si:H) films with high and same order of magnitude photosensitivity (-10^5) but different stability were prepared by using microwave electron cyclotron resonance chemical vapour deposition system under the different deposition conditions. It was proposed that there was no direct correlation between the photosensitivity and the hydrogen content (CH) as well as H-Si bonding configurations, but for the stability, they were the critical factors. The experimental results indicated that higher substrate temperature, hydrogen dilution ratio and lower deposition rate played an important role in improving the microstructure of a-Si:H films. We used hydrogen elimination model to explain our experimental results. 相似文献
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We report an 8-channel wavelength-mode optical pulse interleaver on a silicon photonic chip.Wavelength-and mode-division multiplexing techniques are combined to increase the repetition rate of the pulses without adding the complexity of a single dimension.The interleaver uses a cascaded Mach–Zehnder interferometer architecture as a wavelength-division(de)multiplexer,an asymmetric directional coupler as a mode(de)multiplexer,and various lengths of silicon waveguides as delay lines.A pulse sequence with a time interval of 125 ps is implemented with the repetition rate being eight times that of the initial one.The demonstrated wavelength-mode multiplexing approach opens a new route for the generation of high-speed optical pulses. 相似文献
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Fuchao Yang Shuyi MaXiaolei Zhang Meng ZhangFaming Li Jing LiuQiang Zhao 《Superlattices and Microstructures》2012
Both ZnO and Cu doped ZnO films with strong c-axis preferred orientation have been successfully prepared on porous silicon substrate, formed by electrochemical anodization, using radio frequency reactive magnetron sputtering method. X-ray diffraction measurements showed that the intensity of (0 0 2) diffraction peak first decreased and then increased with the Cu doping content increasing. Meanwhile new weak (1 0 0), (1 0 1), (1 0 2) and (1 1 0) diffraction peaks appeared after doping. The optical band edge of ZnO:Cu films, deduced from the optical absorption spectra, shifted to a longer wavelength comparing with the undoped sample and we attributed this red shift phenomenon to the decreasing of carrier concentration. The broad light emission from 350 to 800 nm was obtained by combining the blue–green emission from ZnO with red–orange emission from porous silicon. This could be used as a source of white light emitting diode chips underlying the importance of our work. The variation and origin of the emission peaks were discussed through the Gaussian deconvolution, and the Raman scattering spectral revealed the characteristics of porous silicon and multiphonon processes. 相似文献
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Role of amorphous silicon domains of Er^3+ emission in the Er—doped hydrogenated amorphous silicon suboxide film 下载免费PDF全文
An investigation on the correlation between amorphous Si (a-Si) domains and Er^{3+} emission in the Er-doped hydrogenated amorphous silicon suboxide (a-Si:O:H) film is presented. On one hand, a-Si domains provide sufficient carriers for Er^{3+} carrier-mediated excitation which has been proved to be the highest excitation path for Er^{3+} ion; on the other hand, hydrogen diffusion from a-Si domains to amorphous silicon oxide (a-SiO_x) matrix during annealing has been found and this possibly decreases the number of nonradiative centres around Er^{3+} ions. This study provides a better understanding of the role of a-Si domains on Er^{3+} emission in a-Si:O:H films. 相似文献
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N. B. Urli 《辐射效应与固体损伤》2013,168(1-2):93-97
Abstract Annealing behavior of electrical properties and photoluminescence spectra both at 77 °K in electron-irradiated melt-grown n-GaAs were investigated. Defects electrically active in the Hall mobility and carrier removal anneal through two stages centered at 250° and 460 °K. From the temperature dependence of carrier concentration the existence of a defect level located near 0.15 eV below the conduction band is supposed. Several emission bands are resolved at 1.51, 1.47, 1.415, 1.305 and ~1.2 eV in photoluminescence experiments. Electron irradiation (1.5–2.0 MeV) causes a remarkable decrease in emission intensity of 1.51 and ~1.2 eV bands. Recovery of emission intensity occurs remarkably when samples are annealed to 520 °K which would correspond to the 460 °K annealing stage for carrier concentration and Hall mobility. The 250 °K annealing stage is not observed in photoluminescence experiments. The 1.415 eV peak appears clearly after irradiation and grows remarkably with the 520 °K annealing, especially in Si-doped samples, resulting in large reverse annealing. This band is tentatively speculated to be a complex of Si on As site with As vacancy. Moreover, in samples doped with Te a new emission band at 1.305 eV (9500 Å) is observed after 470°–620 °K annealing. 相似文献
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GUO Hengqun 《Chinese Journal of Lasers》1994,3(6):557-563
Photoluminescence quenching of porous silicon by noble metal adsorbates¥GUOHengqun(DepartmentofAppliedPhysics,HuaqiaoUniyersi... 相似文献