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ABSTRACT: Thermocapillary and chemicapillary effects are known to coexist in a material molten pool when irradiated by a pulse laser.
According to the effects, we fabricate various patterns with different shapes on a Sb2Te3 phase change thin film by precisely adjusting the pulse energy. In this process, the laser power is fixed at 5.0mW, and
the pulse width is adjusted from 100 ns to 5 ns. The shape of the patterns gradually changes from a dimple-bowl shape, a dome
shape, a “Sombrero” shape to a deep-bowl shape following an increase in the pulse energy, which corresponds to the crystallization-threshold,
bump-threshold, rupture-threshold, and ablation-threshold of the material. The different patterns are the results of the competition
between the thermocapillary and chemicapillary effects in the molten pool, which determine the nature of the flow and lead
to the different patterns in different laser parameters.
Applied Physics A 05/2012; 103(1):139-147. · 1.63 Impact Factor
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ABSTRACT: The eye-beads dating to the early Warring States Period unearthed from Xu Jialing Tomb in Xichuan County of Henan Province,
China are studied. The structure and the chemical composition of the samples are analysed by the undestructive methods of
X-ray diffraction (XRD) and the Proton Induced X-ray Emission (PIXE) technique. The results show that these eye-beads are
of glass state. Its chemical composition indicates that they belong to the glass of soda lime silicate system (Na2O-CaO-SiO2). By comparing the decorative design and the chemical composition of the samples with those from ancient Babylon and ancient
Egypt, we think that these ancient eye-beads in Xichuan were most possibly imported from the West.
Science in China Series E Technological Sciences 05/2012; 52(4):922-927. · 1.02 Impact Factor
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ABSTRACT: Three novel metal(II) complexes, CoL2, NiL2 and CuL2 (L = (Z)-4-(2-(1,3-dimethyl-5-oxo-1H-pyrazol-4(5H)-ylidene)hydrazinyl)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one were
synthesized. Their structures were postulated based on elemental analyses, 1H NMR, ESI-MS, FT-IR spectra and UV-vis spectra. The effect of different central metal(II) ions on absorption bands of the
metal(II) complexes in CHCl3 solutions was researched. The result indicates that the bathochromic shift is CuL2 > NiL2 > CoL2. The absorption properties of thin films and thermal stability of these complexes are also discussed. In addition, the optical
constants (complex refractive index N=n+ik) and thickness of the complex thin films on polished single-crystal silicon substrates were measured by spectroscopic ellipsometry.
Results indicate that the metal(II) complexes would be a promising recording medium candidate for blu-ray recordable optical
storage system due to good absorption at 405nm, high thermal stability and sharp thermal decomposition, and a high n values of 1.35–1.45 and a low k values of 0.33–0.39.
Applied Physics A 05/2012; 102(3):719-724. · 1.63 Impact Factor
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ABSTRACT: In this work, we used the multilayered ZnS–SiO2/AgO
x
/ZnS–SiO2 films as the laser direct writing materials, and pattern structures with different shapes and sizes were directly written
with green laser (λ=488nm). Compared with traditional photoresist materials, the pattern structures can be directly formed in this film structures
without developing and etching procedures and also can be directly written by very low laser power. By tuning the laser parameters
precisely, pattern structures with different sizes and shapes could be obtained as well. The analysis indicates that the formation
mechanism of the pattern structure is mainly due to the volume expansion caused by AgO
x
decomposition into silver particles and oxygen. The oxygen applies pressure to the ZnS–SiO2 layer and makes a hollow shell under the film. The aspect ratios of the patterns rapidly increase from the minimum of 0.012
in laser power of 3.0mW to the maximum of 0.201 in laser power of 5.0mW. The thermal stability of the patterns was also
qualitatively studied.
Applied Physics A 04/2012; 100(2):401-407. · 1.63 Impact Factor
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ABSTRACT: In this note, by using Sb to replace the Al reflective layer in the conventional optical disk, the recording pits with a diameter
380 nm and a depth 50 nm are read out in the device, whose laser wavelength λ is 632.8 nm and numerical aperture (NA) is 0.40.
In the course of reproduction, the readout laser power is 4 mW and the rotation velocity of the disk is 5 m/s. The optimum
Sb film thickness is 28–30 nm and the CNR is 38–40 dB.
Keywordssuper-resolution-optical disk-Sb
Chinese Science Bulletin 04/2012; 47(19):1604-1606. · 1.32 Impact Factor
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ABSTRACT: Based on study of non-isothermal crystallization kinetics and orthogonal test of pulsed-laser crystallization parameters of
Ge1Sb4Te7, minimum nanosecond laser pulse duration (threshold) for crystallization recording was used for optical–electrical hybrid operation. The crystallized bits arrays were optically recorded with minimum pulse duration of 40 ns and
electrically read out with maximum current signal contrast of ∼20 times.
Applied Physics A 04/2012; 98(4):795-800. · 1.63 Impact Factor
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ABSTRACT: A femtosecond laser-irradiated crystallizing technique is tried to convert
amorphous Sb2Te3 film into crystalline film. Sensitive coherent phonon
spectroscopy (CPS) is used to monitor the crystallization of amorphous Sb2Te3
film at the original irradiation site. The CPS reveals that the vibration
strength of two phonon modes that correspond to the characteristic phonon modes
of crystalline Sb2Te3, enhances with increasing laser irradiation fluence
(LIF), showing the rise of the degree of crystallization with LIF and that
femtosecond laser irradiation is a good post-treatment technique. Time-resolved
circularly polarized pump-probe spectroscopy is used to investigate electron
spin relaxation dynamics of the laser-induced crystallized Sb2Te3 film. Spin
relaxation process indeed is observed, confirming the theoretical predictions
on the validity of spin-dependent optical transition selection rule and the
feasibility of transient spin-grating-based optical detection scheme of
spin-plasmon collective modes in Sb2Te3-like topological insulators.
10/2011;
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ABSTRACT: The time-resolved crystallization dynamics of as-deposited amorphous AgInSbTe thin films induced by single picosecond laser pulses has been studied. The crystallization process was shown to be a threshold-dependent multi-stage process. For the same film structure, the total crystallization time does not change significantly with different fluences in a broad fluence range. The total crystallization time can be effectively shortened by an additional thermally conductive silver underlayer. After the film has been primed with a low-fluence single ~30 ps laser pulse, the crystallization process can be simplified to be a monotonic process with a markedly reduced crystallization time.
Journal of Physics D Applied Physics 04/2010; 43(17):175401. · 2.54 Impact Factor
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ABSTRACT: With the development of information, the density and capacity of information storage devices are required to be higher, and the smallest information bit size will be reduced to below the 100 nm accordingly. For the optical data storage and random access memory, the smallest bit size is mainly determined by the optical diffraction limit, which leads to some difficulties to get nanometric information bit by traditional far-field optics method. In order to realize the nano-data storage, one must break the optical diffraction barrier. In this report, we look back the develop story of optical storage, and give novel near-field optics methods for realizing the nano-data storage and nanolithography.
Nanoelectronics Conference (INEC), 2010 3rd International; 02/2010
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ABSTRACT: Multiple Bragg hologram recording was investigated in trimethylolpropane triacrylate based polymer-dispersed liquid-crystal thin films. Ten volume holograms were stored at a single location of less than 0.8 mm2 area with the diffraction efficiencies of 6%–15%, by a simplified method of peristrophic multiplexing, and the formation process of multiple volume holograms was presented. Furthermore, volume hologram capacity was studied both experimentally and theoretically in this film. Based on the maximum of Δn, ∼ 2×10−2, the theoretical capacity of a location could be improved to 25 Bragg holograms with the relatively high diffraction efficiency of 1%, and the holographic storage density of more than 20 Gbits/in.2 was achieved just by peristrophic multiplexing. Finally, electrically switchability for multiple holograms with a low threshold voltage of ∼ 3 V/μm was realized, which demonstrates that this material is a potential medium for electrically controlled holographic storage or diffraction device.
Applied Physics Letters 11/2009; 95(20):201105-201105-3. · 3.84 Impact Factor
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ABSTRACT: Fast phase transition processes on Ge <sub>2</sub> Sb <sub>2</sub> Te <sub>5</sub> film induced by picosecond laser pulses were studied using time-resolved reflectivity measurements. It was found that after picosecond laser pulse priming, reversible switching could be occurred upon picosecond laser pulse irradiation with the same well-chosen fluence. This is very different from general knowledge that reversible phase change process will be induced by laser pulses with different powers; that is, amorphization process needs much higher fluence than crystallization process. The possible mechanism was discussed qualitatively by a melting-cooling model.
Journal of Applied Physics 10/2009; · 2.17 Impact Factor
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ABSTRACT: Using first-principles simulations, we propose a simple mechanism and an easy-controlled method for reversible modification of supported nanoclusters on surfaces with atomic precision. As illustrated, individual atoms at edges of a Al nanocluster on a Al(111) surface can be extracted vertically and repositioned with a Al trimer-apex tip, which allows to rearrange a ten-atom hexagonal nanocluster to a triangular one in a reversible way. The governing mechanism is the atomic tip-surface interaction whose distinct dependence on directions plays a key role in manipulations.
Applied Physics Letters 08/2009; 95(7):073105-073105-3. · 3.84 Impact Factor
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ABSTRACT: We report multiple holographic recording and optical address recognition schemes in Methyl Red-doped liquid-crystal film without an applied electric field. Ten gratings are recorded at a single location of a 5 mm2 area by using optical multiplexing methods, and the diffraction efficiencies are studied for multiplexed gratings. Diffraction behavior of angular and peristrophic multiplexed gratings is discussed, and two methods that involve recording angles and peristrophic rotation angles are presented for optical recognition.
Applied Optics 07/2009; 48(16):3014-8. · 1.41 Impact Factor
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ABSTRACT: The super-resolution of the nonlinear multilayer structure is analyzed, and the results indicate that the super-resolution stems from the internal multi-interference. For the nonlinear Si-based thin film, the reflected spot size can be reduced to 0.5 times that of the original spot, and the super-resolution pit arrays on the discs are dynamically read out experimentally.
Journal of Nanoscience and Nanotechnology 03/2009; 9(2):982-4. · 1.56 Impact Factor
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ABSTRACT: The dependence of thermal properties of Ag8In14Sb55Te23 phase-change memory materials in crystalline and amorphous states on temperature was measured and analyzed. The results show
that in the crystalline state, the thermal properties monotonically decrease with the temperature and present obvious crystalline
semiconductor characteristics. The heat capacity, thermal diffusivity, and thermal conductivity decrease from 0.35J/g K,
1.85mm2/s, and 4.0W/m K at 300K to 0.025J/g K, 1.475mm2/s, and 0.25W/m K at 600K, respectively. In the amorphous state, while the dependence of thermal properties on temperature
does not present significant changes, the materials retain the glass-like thermal characteristics. Within the temperature
range from 320K to 440K, the heat capacity fluctuates between 0.27J/g K and 0.075J/g K, the thermal diffusivity basically
maintains at 0.525mm2/s, and the thermal conductivity decreases from 1.02W/m K at 320K to 0.2W/m K at 440K. Whether in the crystalline or amorphous
state, Ag8In14Sb55Te23 are more thermally active than Ge2Sb2Te5, that is, the Ag8In14Sb55Te23 composites bear stronger thermal conduction and diffusion than the Ge2Sb2Te5 phase-change memory materials.
Applied Physics A 02/2009; 94(3):627-631. · 1.63 Impact Factor
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ABSTRACT: We study the reliability of the lateral manipulation of a single Cu adatom on a Cu(111) surface with single-atom, dimer and trimer apex tips using both semiempirical and first-principles simulations. The dependence of the manipulation reliability on tip height is investigated. For the single-atom apex tip the manipulation reliability increases monotonically with decreasing tip height. For the dimer and trimer apex tips the manipulation reliability is greatly improved compared to that for the single-atom apex tip over a certain tip-height range. Two kinds of mechanism are found responsible for this improvement. One is the so-called enhanced interaction mechanism in which the lateral tip-adatom interaction in the manipulation direction is improved. The other is the suspended atom mechanism in which the relative lateral trapping ability of the tip is improved due to the strong vertical attraction of the tip on the adatom. Both mechanisms occur in the manipulations with the trimer apex tip, while in those with the dimer apex tip only the former is effective. Moreover, we present a method to realize reversible vertical manipulation of a single atom on a Cu(111) surface with the trimer apex tip, based on its strong vertical and lateral attraction on the adatom.
Nanotechnology 08/2008; 19(33):335710. · 3.98 Impact Factor
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ABSTRACT: A new chelating ligand, 2-(2-(5-tert-butylisoxazol-3-yl)hydrazono)-N-(2,4-dimethylphenyl)-3-oxobutanamide (HL), and its four binuclear transition metal complexes, M(2)(L)(2) (micro-OCH(3))(2) [M=Ni(II), Co(II), Cu(II), Zn(II)], were synthesized using the procedure of diazotization, coupling and metallization. Their structures were postulated based on elemental analysis, (1)H NMR, MALDI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films of these complexes on K9 glass substrates were prepared using the spin-coating method and their absorption properties were evaluated. The thermal properties of the metal(II) complexes were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Different thermodynamic and kinetic parameters namely activation energy (E*), enthalpy of activation (DeltaH*), entropy of activation (DeltaS*) and free energy change of activation (DeltaG*) are calculated using Coats-Redfern (CR) equation.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 12/2007; 68(3):918-26. · 2.10 Impact Factor
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ABSTRACT: Aluminum-doped Ge(2)Sb(2)Te(5) (Al(x)GST) films were deposited on Si(100) substrates by co-magnetron sputtering system. The Aluminum concentrations in these films are determined by X-ray photoelectron spectroscopy (XPS). The influence of Al doping upon phase change characteristics of these Al(x)GST alloy films has been investigated by X-ray diffraction (XRD) and a temperature-regulable UVISEL(TM) typed spectroscopic ellipsometry (TRSE). With the augment of Al doping concentration, the crystalline temperatures of Al(x)GST films went up while annealing, and the face-centered-cubic (fcc) phase had high thermal stability. The reflectivity contrast of the films increases obviously, which is effective to improve the signal to noise ratio (SNR) for optical phase-change storage.
Optics Express 09/2007; 15(17):10584-90. · 3.59 Impact Factor
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ABSTRACT: Two kinds of nickel(II) and copper(II) beta-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2007; 66(4-5):1024-9. · 2.10 Impact Factor
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ABSTRACT: In this comment, problems associated with an oversimplified FDTD based model used for trapping force calculation in recent papers "Computation of the optical trapping force using an FDTD based technique" [Opt. Express 13, 3707 (2005)], and "Rigorous time domain simulation of momentum transfer between light and microscopic particles in optical trapping" [Opt. Express 12, 2220 (2004)] are discussed. A more rigorous model using in Poynting vector is also presented.
Optics Express 01/2007; 14(25):12494-6. · 3.59 Impact Factor
