共查询到20条相似文献,搜索用时 15 毫秒
1.
G.S. Wang X.J. Meng Z.Q. Lai J. Yu J.L. Sun S.L. Guo J.H. Chu 《Applied Physics A: Materials Science & Processing》2003,76(1):83-86
Ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films have been grown on Pt/Ti/SiO2/Si substrates by chemical solution methods. X-ray diffraction analysis shows that BLT thin films are polycrystalline with
(171)-preferential orientation. Atomic force microscopy investigation shows that they have large grains about 120 nm in size.
A Pt/BLT/Pt capacitor has been fabricated and showed excellent ferroelectricity, with a remnant polarization and coercive
field of 24 μC/cm2 and 116 kV/cm, respectively. The capacitor shows no polarization fatigue up to 109 switching cycles. The optical constants (n,k) of the BLT thin films in the wavelength range 0.35–1.7 μm were obtained by
spectroscopic ellipsometry measurements, and the band-gap energy was found to be about 3.25 eV.
Received: 16 October 2001 / Accepted: 6 January 2002 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +86-21/65830-734, E-mail: gswang@mail.sitp.ac.cn 相似文献
2.
V.C. Selvaraju S. Asokan V. Srinivasan 《Applied Physics A: Materials Science & Processing》2003,77(1):149-153
The I–V characteristics of bulk As40Te60-xSex and As35Te65-xSex glasses have been studied with a current sweep of 0–18 mA-0, over a wide range of compositions (4≤x≤22). All the glasses
studied showed a threshold electrical switching behaviour. The number of switching cycles withstood by the samples has been
found to depend on the ON-state current. It is seen that the switching voltages increase with increase in selenium content.
Further, the switching voltages are found to be almost independent of the thickness of the sample (d), in the range 0.18–0.3 mm.
Also, the switching voltages and the number of switching cycles withstood by the samples are found to decrease with temperature.
Received: 6 November 2002 / Accepted: 8 November 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +91-80/360-0135, E-mail: sasokan@isu.iisc.ernet.in 相似文献
3.
Y. Liu D. Li R.Y. Zhu G.J. You S.X. Qian Y. Yang J.L. Shi 《Applied physics. B, Lasers and optics》2003,76(4):435-439
Au-core CdS-shell composite nanoparticles were synthesized by a direct self-assembly process and integrated into BaTiO3 thin films. Characterization by transmission electron microscopy showed that the average diameter of these composite nanoparticles
was about 8 nm. Using the femtosecond time-resolved optical Kerr effect method, we investigated the third-order nonlinear
optical response of the Au@CdS nanoparticles embedded in the BaTiO3 thin films at a wavelength of 800 nm. An ultrafast nonlinear response and a large effective third-order nonlinear susceptibility
of χ(3)=7.7×10-11 esu were observed. We attributed the enhancement of the third-order optical nonlinearity to a localized electric field effect
originating from the core-shell structure under off-surface-plasmon resonance conditions.
Received: 13 May 2002 / Revised version: 23 October 2002 / Published online: 3 April 2003
RID="*"
ID="*"Corresponding author. Fax: +86-21/6510-4949, E-mail: sxqian@fudan.ac.cn 相似文献
4.
We report on a passively Q-switched diode-pumped Nd:YVO4 laser polarized along the a axis (corresponding to the smallest value of emission cross section at 1064 nm), generating 157-μJ
pulses with 6.0-ns time duration (>20 kW peak power) and 3.6 W of average power at 1064 nm with good beam quality (M2<1.4). The selection of the polarization was performed by a novel technique relying on the birefringence of the laser crystal
and on the misalignment sensitivity of the resonator.
Received: 30 September 2002 /
Revised version: 22 November 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +39-382/422583, E-mail: agnesi@ele.unipv.it 相似文献
5.
Y. Du M.-S. Zhang J. Wu L. Kang S. Yang P. Wu Z. Yin 《Applied Physics A: Materials Science & Processing》2003,76(7):1105-1108
SrTiO3 thin films were prepared on a fused-quartz substrate by pulsed laser deposition (PLD). Dense and homogeneous films with a
thickness of 260 nm were prepared. Optical constants (refractive index n and extinction coefficient k) were determined from
the transmittance spectra using the envelope method. The optical band gap energy of the films was found to be 3.58 eV, higher
than the 3.22 eV for bulk SrTiO3, attributable to the film stress exerted by the substrate. The dispersion relation of the refractive index vs. wavelength
follows the single electronic oscillator model. The refractive index and the packing density for the PLD-prepared SrTiO3 thin films are higher than those for the SrTiO3 films prepared by physical vapor deposition, sol–gel and RF sputtering.
Received: 18 March 2002 / Accepted: 7 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: mszhang@nju.edu.cn 相似文献
6.
E. Millon J. Perrière R.M. Défourneau D. Défourneau O. Albert J. Etchepare 《Applied Physics A: Materials Science & Processing》2003,77(1):73-80
The elemental composition and the surface morphology of thin films grown by laser ablation of barium titanate with femtosecond
pulses at 620 nm laser wavelength have been systematically studied according to the experimental pulsed-laser deposition parameters
: laser energy density, oxygen pressure, substrate temperature, target–substrate distance and substrate position (in- and
off-axis geometry). Firstly, even at high temperature (700 °C), the deposits consist of coalesced particles up to 1-μm in
size, mixed in a poorly crystallised tetragonal BaTiO3 thin film. The particles formed in femtosecond pulsed-laser deposition induce a high surface roughness, which is observed
whatever the experimental growth conditions and does not correspond to the droplets often observed during laser ablation in
the nanosecond regime. As shown by plasma expansion dynamics, these particles propagate toward the substrate in the plasma
plume with a low velocity, and are assumed to be produced by gas-phase reactions. Moreover, the cationic concentration evaluated
through the Ba/Ti ratio strongly depends on the oxygen pressure in the ablation chamber and the angular position of the substrate
along the normal to the target at laser impact. Indeed, the films appear to be enriched in the heavy element (Ba) when the
substrate is located at high angular deviation. This fact is correlated to an increase in the lighter species (i.e. Ti) in
the central part of the plasma plume.
Received: 30 April 2002 / Accepted: 26 August 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +33-1/4354-2878, E-mail: millon@gps.jussieu.fr
RID="**"
ID="**"Also at: LSMCL, Université de Metz, 57078 Metz Cedex 3, France 相似文献
7.
Poling dynamics of lithium niobate crystals 总被引:2,自引:0,他引:2
Ferroelectric domain reversal via electric field poling of congruently melting lithium niobate (LiNbO3) crystals is investigated. An electro-optic interferometric observation technique reveals spatial and temporal dynamics of
the poling process. Starting from seeds, the domains grow until the entire crystal has a switched polarization. During the
switching process the boundaries are preferentially aligned along the crystallographic axes. The coercive field between two
sequenced domain inversions is transiently reduced after a poling event, and recovers exponentially with a time constant of
about half a minute. No light-induced change of the recovery time constant, neither with green nor with ultraviolet light,
is observed. The results are of relevance for domain engineering of LiNbO3 crystals.
Received: 6 February 2003 / Published online: 9 April 2003
RID="*"
ID="*"Corresponding author. Fax: +49-228/734038, E-mail: wengler@physik.uni-bonn.de 相似文献
8.
M.Y. Goulkov T. Granzow U. Dörfler T. Woike M. Imlau R. Pankrath 《Applied physics. B, Lasers and optics》2003,76(4):407-416
We study light-induced scattering (beam-fanning) in the photorefractive crystal SBN:Ce as a function of the polar structure
of the crystal. The spatial structure of the beam-fanning is measured at different externally applied electric fields, and
an optical hysteresis is found in the scattering. It is shown that the scattering hysteresis results from a polarization hysteresis
typical for ferroelectrics in the polar phase. New information about primary scattering in SBN is obtained, and a corresponding
model of its origin is proposed. It is shown that the intensity and angular distribution of the primary scattering strongly
depend on the polar structure of the crystal and can be affected by the subsequent action of an external field and coherent
illumination.
Received: 27 August 2002 / Revised version: 19 December 2002 / Published online: 26 March 2003
RID="*"
ID="*"Corresponding author. E-mail: mirco.imlau@uni-osnabrueck.de 相似文献
9.
R.L.D. Whitby W.K. Hsu C.B. Boothroyd K.S. Brigatti H.W. Kroto D.R.M. Walton 《Applied Physics A: Materials Science & Processing》2003,76(4):527-532
Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.
Received: 17 June 2002 / Accepted: 19 June 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1273/677-196, E-mail: d.walton@sussex.ac.uk 相似文献
10.
S.S. Yi J.S. Bae B.K. Moon J.H. Jeong I.W. Kim H.L. Park 《Applied Physics A: Materials Science & Processing》2003,76(3):433-437
ZnGa2O4 thin-film phosphors have been grown on Si(100), Al2O3(0001) and MgO(100) substrates using pulsed laser deposition. The structural characterization was carried out on a series
of ZnGa2O4 films grown on various substrates under various substrate temperatures and oxygen pressures. The films grown on these substrates
not only have different crystallinity and surface morphology, but also different Zn/Ga composition ratio. The crystallinity
and photoluminescence (PL) of the ZnGa2O4 films are highly dependent on the deposition conditions, in particular the stoichiometry ratio of Zn/Ga and the kind of substrate.
The variation of Zn/Ga in the films also depends on not only the oxygen pressure but also the substrate temperature during
deposition. The PL properties of pulsed laser deposited ZnGa2O4 thin films have indicated that Al2O3(0001) and MgO(100) are promising substrates for the growth of high-quality ZnGa2O4 thin films and that the luminescence brightness depends on the substrate. The luminescence spectra show a broad band extending
from 350 to 600 nm and peaking at 460 nm.
Received: 11 July 2002 / Accepted: 31 July 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +82-51-6206356, E-mail: jhjeong@pknu.ac.kr 相似文献
11.
T. Okazaki T. Shimada K. Suenaga Y. Ohno T. Mizutani J. Lee Y. Kuk H. Shinohara 《Applied Physics A: Materials Science & Processing》2003,76(4):475-478
Electronic properties of Gd@C82 metallofullerene peapods, (Gd@C82)n@SWNTs, were investigated by electron energy-loss spectroscopy (EELS), scanning tunneling microscopy and spectroscopy (STM/STS),
and field-effect transistor (FET) transport measurements. The results indicate that the electronic structure of Gd@C82 metallofullerene peapods is completely different from that of intact single-walled nanotubes (SWNTs). For example, Gd@C82-peapod-FETs show ambipolar behavior which is not observed in the empty SWNT-FETs under our experimental conditions. Furthermore,
in semiconducting nanotubes the band gap can be varied from ∼0.5 to ∼0.1 eV using inserted Gd@C82 endohedral metallofullerenes with a spatial periodicity of 1.1 to 8.0 nm, depending on the density of the fullerenes. The
present findings suggest that metallofullerene peapods may point the way toward novel electronic devices.
Received: 6 September 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-52/789-1169, E-mail: noris@cc.nagoya-u.ac.jp 相似文献
12.
The ac electrical properties of metal-free phthalocyanine (H2PC) thin films have been studied in the frequency range from 102 to 2×104 Hz and in the temperature range from 150 to 475 K. The ac conductivity σ was found to vary as ωs with the index s≤1. Although these general values of s appear to be consistent with a hopping process, the present σ values
do not increase monotonically with temperature. At low frequency, the capacitance and loss tangent were found to be constant
over the entire frequency range, in good qualitative agreement with the equivalent circuit model consisting of an inherent
capacitance in parallel with a resistive element. Moreover, at constant frequency, the two parameters increased with increasing
temperature up to approximately 300 K. Above this temperature, another sharp decrease in both capacitance and loss tangent
was obtained. This type of behavior was interpreted in terms of nomadic (delocalized) polarization, which leads to an increase
in the dielectric constant. The drastic decrease of the capacitance and loss tangent observed above room temperature is thought
to be related to the decrease in the dielectric constant, which results from the inability of the domains to hold the increases
in free charge carrier concentration due to the increase of temperature.
Received: 6 December 2001 / Accepted: 7 January 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: +972-2/279-6960, E-mail: asaleh@science.alquds.edu 相似文献
13.
β-Ga2O3 nanowires have been synthesized using Ga metal and H2O vapor at 800 °C in the presence of Ni catalyst on the substrate. Remarkable reduction of the diameter and increase of the
length of the Ga2O3 nanowires are achieved by separation of Ga metal and H2O vapor before they reach the substrate. Transmission electron microscopy analyses indicate that the β-Ga2O3 nanowires possess a single-crystalline structure. Photoluminescence measurements show two broad emission bands centered at
290 nm and 390 nm at room temperature.
Received: 27 June 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +886-6/234-4496, E-mail: wujj@mail.ncku.edu.tw 相似文献
14.
R. Denk K. Piglmayer D. Bäuerle 《Applied Physics A: Materials Science & Processing》2003,76(4):549-550
A regular lattice of a-SiO2 microspheres on a quartz support is used as a microlens array for laser-induced surface patterning by etching and deposition
of W in atmospheres of WF6 and WF6+H2, respectively.
Received: 22 July 2002 / Accepted: 30 July 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +43-732/2468-9242, Email: dieter.baeuerle@jku.at 相似文献
15.
Investigation of size-driven phase transition in bismuth titanate nanocrystals by Raman spectroscopy 总被引:2,自引:0,他引:2
Y.L. Du M.S. Zhang Q. Chen Z. Yin 《Applied Physics A: Materials Science & Processing》2003,76(7):1099-1103
Raman spectroscopy was used to investigate the lattice dynamics and structural transformations in bismuth titanate (Bi4Ti3O12) nanocrystals prepared by a chemical coprecipitation technique. The crystal structure of the samples of different grain sizes
was determined by X-ray-diffraction analysis. The evolution of the Raman spectrum with grain size was characterized by an
intensity decrease, a broadening of the line width, a frequency shift, and the disappearance of the Raman mode. The results
revealed the appearance of a size-driven phase transition from orthorhombic to tetragonal phases at a critical size of 44 nm.
This result is quite consistent with the X-ray-diffraction measurement and differential thermal analysis. The origin was attributed
to the grain-size effect and explained by the surface-energy mechanism.
Received: 26 June 2002 / Accepted: 18 August 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-25/3595535, E-mail: msz@nju.edu.cn 相似文献
16.
Manganese oxide (hausmannite) nanowires were prepared by annealing precursor powders at a temperature of 800 °C for 3 h, which
were produced in a novel inverse microemulsion (IμE) system. The microstructures of the as-prepared Mn3O4 nanowires were investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectra. It has been
found that the Mn3O4 nanowires were relatively straight and their surfaces were smooth with a typical diameter of 75–150 nm. The formation mechanism
of the Mn3O4 nanowires is discussed.
Received: 30 May 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献
17.
Ultrahigh-efficiency TEM00 operation is demonstrated in a diode-pumped Nd:YVO4 laser in a bounce amplifier geometry using a specially designed astigmatically optimised cavity configuration. Optical efficiency
>68% is demonstrated and up to 27.1 W of output power for multimode operation. For single-mode TEM00 operation, an output power of 23.1 W for 39.5 W of diode pumping was produced with beam propagation parameters of Mx
2=1.3 and My
2=1.1.
Received: 10 October 2002 / Revised version: 9 December 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: a.minassian@ic.ac.uk 相似文献
18.
G. Padeletti A. Cusmá G.M. Ingo A. Santoni S. Loreti C. Minarini M. Viticoli 《Applied Physics A: Materials Science & Processing》2003,76(5):801-808
In the last few years, intensive research activity has been focused on the development of suitable synthesis methods for high-permittivity
materials, used for the realization of next-generation microdevices able to fulfil the previsions of the Technology Roadmap
of Semiconductors. The use of high-permittivity materials can overcome the difficulties concerning the production of SiO2-based ultra-thin dielectrics, such as the generation of pinholes and the non-uniformity of the film, which may result in
a malfunction in high-density systems. Recently, zirconium titanate thin films were discovered to have very interesting dielectric
properties, which suggests a use for them in microwave integrated systems, such as receivers or DRAMs, since they are monophasic,
have little dissipation and show a good thermal stability and a high value for the dielectric constant, independent of frequency
in the range from kilohertz to a few gigahertz. Real application is possible only in strict connection with the development
of a suitable preparation method which allows production with controlled and reproducible characteristics. In this work, the
synthesis and characterization of ZrxTi1-xO4 (ZT) thin films grown via MO-CVD is described, studying the influence of growth parameters on their structural, chemical
and physical properties.
Received: 17 June 2002 / Accepted: 24 June 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +39-06/9067-2445, E-mail: Pad@mlib.cnr.it 相似文献
19.
R. Steiner H.-G. Boyen M. Krieger A. Plettl P. Widmayer P. Ziemann F. Banhart R. Kilper P. Oelhafen 《Applied Physics A: Materials Science & Processing》2003,76(1):5-13
[Fe/B]n ≥2 multilayers were prepared by thermal evaporation, ion-beam sputtering and laser ablation. By applying in situ electron spectroscopies
(UPS, XPS) and monitoring the electrical resistance during layer growth, evidence could be provided for the occurrence of
interface reactions within the range of studied deposition temperatures (77 K ≤T ≤300 K). These reactions result in amorphous
FexB100-x phases, which are spatially restricted to a width of less than 3 nm at the original interface. The amorphicity of the reacted
interlayers was unequivocally proven by additional high-resolution electron microscopy (HRTEM) and their characteristically
changed magnetic properties. Due to the well-defined width of the interface reaction, homogeneous amorphous FexB100-x films can be obtained by reducing the individual Fe and B layer thicknesses to below the above reaction depth, while for
larger thicknesses layer sequences of the crystalline/amorphous/crystalline type will result.
Received: 30 January 2002 / Accepted: 31 January 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-731/502-2963, E-mail: hans-gerd.boyen@physik.uni-ulm.de 相似文献
20.
C. Cheng 《Applied physics. B, Lasers and optics》2003,76(1):27-32
For obtaining the maximal output power, five lasing gas mixtures (CO2, N2, He, Xe and H2) in a sealed-off CO2 laser are optimized by applying a genetic algorithm and solving CO2 laser kinetics equations. A comparison of numerical simulations shows that the optimal pressures of CO2 and N2 are 1.15 Torr and 7.32 Torr, respectively. Accordingly, the maximum laser power of 124 W is obtained by utilizing the optimal
gas combination and an optimized resonator with a length of 1.2 m.
Received: 14 August 2002 / Published online: 22 January 2003
The project supported by Zhejiang Provincial Natural Science Foundation of China (No. 602098).
RID="*"
ID="*"Corresponding author. Fax: +86-571/8832-0369, E-mail: chengch@mail.hz.zj.cn 相似文献