共查询到20条相似文献,搜索用时 31 毫秒
1.
Polarization fatigue in poly(vinylidene fluoride (78%)-trifluoroethylene (22%)) ferroelectric thin films: a pulse train study
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper investigates the influences of polarization fatigue on remanent polarization and switching time by pulse train measurements in ferroelectric poly(vinylidene fluoride (78%) and trifluoroethylene (22%)) thin films. Fatigue was carried out by a series of bipolar switching pulses with constant pulse width (on-time) and various interval times between pulses (off-time). The experimental observations indicated that the off-time period showed no obvious influence on fatigue rate and the switching time increased with the increase of fatigue cycles. The origination of these phenomena was discussed according to the charge injection model. 相似文献
2.
Determining the influence of ferroelectric polarization on electrical characteristics in organic ferroelectric field-effect transistors
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
《中国物理 B》2015,(5)
Organic ferroelectric field-effect transistors(OFeFETs) are regarded as a promising technology for low-cost flexible memories. However, the electrical instability is still a critical obstacle, which limits the commercialization process. Based on already established models for polarization in ferroelectrics and charge transport in OFeFETs, simulation work is performed to determine the influence of polarization fatigue and ferroelectric switching transient on electrical characteristics in OFeFETs. The polarization fatigue results in the decrease of the on-state drain current and the memory window width and thus degrades the memory performance. The output measurements during the ferroelectric switching process show a hysteresis due to the instable polarization. In the on/off measurements, a large writing/erasing pulse frequency weakens the polarization modulation and thus results in a small separation between on- and off-state drain currents. According to the electrical properties of the ferroelectric layer, suggestions are given to obtain optimal electrical characterization for OFeFETs. 相似文献
3.
X. F. Xu N. Xu W. Hu J. D. Wu Y. Q. Shen Z. F. Ying 《Applied Physics A: Materials Science & Processing》2009,96(2):415-421
The Fourier transform infrared (FTIR) spectra and switching current response in sodium nitrite:poly(vinyl alcohol) nanocomposite
films have been studied as a function of composition of NaNO2. The switching current data fitted well to infinite-grain model (IGM) in the region t<t
s
and to finite-grain model (FGM) in the region t≥t
s
. The microscopic parameters like the dimensionality, the domain wall velocity, and the nucleation rate have been evaluated
which provide more physical insight of the switching phenomena in the composite films. The polarization current and nucleation
rate are optimum in 50 wt.% composite film and have been discussed in terms of grain size and strain variations with the composition.
The effect of applied field and pulse width variation on the switching behavior of 50 wt.% composition has also been studied.
The exponential field dependence of the domain wall velocity and the nucleation rate indicate that nucleation mechanism is
responsible for switching phenomena in the composite films. The writing pulse width affects significantly on the switching
behavior of the composite films. 相似文献
4.
Ultra-short laser ablation of metals and semiconductors: evidence of ultra-fast Coulomb explosion 总被引:1,自引:0,他引:1
H. Dachraoui W. Husinsky G. Betz 《Applied Physics A: Materials Science & Processing》2006,83(2):333-336
We have studied ultra-fast laser ablation of Si and a metal via the neutral and ion yield, the energy distribution of emitted
neutrals and the charge distribution as a function of the laser pulse width. Two processes, one leading to the ejection of
fast (3–7 eV), the other to slow thermal particles, can be identified. The origin of the first process can be correlated with
laser pulse widths (or pump–probe delays) and processes on a time scale below 100 fs. Results for Si confirm recent findings
for Coulomb explosion (CE) and we show for the first time that CE exists as a mechanism of material removal from metals for
ultra-short laser pulses.
PACS 06.60.Jn; 79.20.Ds; 79.60.Bm; 42.62.Fi; 71.20.-b 相似文献
5.
Y.C. Kong L.Q. Hu Y.D. Zheng C.H. Zhou C. Chen S.L. Gu R. Zhang P. Han R.L. Jiang Y. Shi 《Applied Physics A: Materials Science & Processing》2008,90(3):545-548
Charge storage characteristics in an Al/AlN/p-Si metal–insulator–semiconductor (MIS) structure have been investigated by capacitance–voltage
and long-term capacitance measurements. Good program/erase behavior is observed in the AlN/Si structure, which is attributed
to the trapping and detrapping of charges in deep traps of the AlN layer. In the long-term retention mode, a clear memory
window is found 2000 s after removing a program/erase voltage of ±3 V, indicating good charge retention capability of the
MIS structure. Further investigation shows that for a program pulse width of 500 ms, the charge storage does not occur when
the pulse amplitude is smaller than a threshold value of ∼1 V. The trapped charge density increases linearly with increase
of the pulse amplitude (>1 V) and tends to saturate at 2.5 V. With increasing program pulse width, the trapped charged density
increases a little more than logarithmically.
PACS 73.40.Kp; 72.20.Jv; 71.55.Eq 相似文献
6.
E. A. Konshina M. A. Fedorov A. E. Rybnikova L. P. Amosova N. L. Ivanova M. V. Isaev D. S. Kostomarov 《Technical Physics》2009,54(4):555-560
The dynamics of the electrooptical 90° twist effect in a dual-frequency nematic liquid crystal is investigated for wavelengths
of 0.65 and 1.55μ m. It is shown that the boundary conditions of the interaction between the phases affect the optical threshold
of the twist effect, the contrast, and the working voltage range. The switching time of the twist effect from the off to the
on state upon a variation of the amplitude of a rectangular dc voltage pulse from 15 to 50 V changes from 1.5 to 0.3 ms for
a thickness of the nematic crystal layer of about 7 μ m. The minimal time of switching from the “on” to the “off” state was
3 ms in the case when relaxation of molecules in a cell with asymmetric boundary conditions was controlled electrically. The
dynamic range of transmittance variation at a wavelength of 1.55 μm extended to 30 dB. 相似文献
7.
G. S. Qin T. Sakamoto N. Yamamoto T. Kawanishi H. Sotobayashi T. Suzuki Y. Ohishi 《Laser Physics》2011,21(1):158-162
We demonstrate a general technique for realizing fine control of optical pulse width via doublet gain or loss lines. The optimized
doublet gain or loss lines for fine control of optical pulse width can be designed by using an inverse design method. The
preliminary experimental demonstration of fine control of optical pulse width is performed by using doublet Brillouin gain
lines in an optical fiber. Tunable pulse compression or stretching ratio of 1.47–0.43 accompanying a time delay is achieved
by controlling the separation between two gain lines, for an input pulse train with a 40 ns pulse width and a repetition rate
of 5 MHz, in a 4 km silica fiber with a fixed pump power of 88.1 mW. 相似文献
8.
We derive the width of the Higgs boson into vector bosons. General formulas are derived both for the on–shell decay as well for the off–shell decays, and , where . For the off-shell decays the width of the decaying vector boson is properly included. The formulas are valid both for the
Standard Model as well as for arbitrary extensions. As an example we study in detail the gauge-invariant effective Lagrangian
models where we can have sizable enhancements over the Standard Model that could be observed at LEP.
Received: 31 July 1998 / Revised version: 23 September 1998 / Published online: 6 November 1998 相似文献
9.
Ferroelectric Properties of Polycrystalline Ceramics with Dipolar Defect Simulated from the Potts--Ising Model
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Physical properties of polycrystailine ferroelectrics including the contributions of the fixed dipolar defects and the average grain size in the Potts-Ising model are simulated by using the Monte Carlo method. Domain pattern, hysteresis loop and switching current of the polarization reversal process are obtained. Two processes are considered in our simulation. In the first one, the grain texture of ferroelectric ceramics are produced from the Ports model, and then the Ising model is implemented in the obtained polycrystailine texture to produce the domain pattern, hysteresis loop and switching current. It is concluded that the defect has the ability to decrease the remnant polarization P~ as well as the coercive field E~. The back switching is obviously observed after the electric field is off, and it shows some variation after introducing the fixed dipolar defect. Meanwhile, the spike of the switching current is found to lower with the increasing defect concentration and the decreasing average grain size. 相似文献
10.
A. G. Maslovskaya T. K. Barabash 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(1):37-43
The features of polarization reversal processes of ferroelectric crystals are analyzed under the condition that electron beams
of a scanning electron microscope are injected into the subsurface layer of a sample. The proposed mathematical model describes
the dynamics of the polarization switching of a ferroelectric crystal using the injection contact technique. The simulation
relies on the basic principles of scale invariance in domain structure evolution. The polarization switching current of ferroelectric
crystals is investigated as the dynamic characteristic of a finite medium exhibiting fractal behavior. The application of
fractal and multifractal analysis of a time series enables us to calculate the fractal dimension of the polarization reversal
process under injection conditions. 相似文献
11.
The existence of surface polaritons in a dielectric at a boundary with an ideal metal or superconductor in a static electric
field is predicted. The frequency regions in which polaritons exist are substantially different for opposite orientations
of the electric field, so that a change in the direction of the field signifies “switching on” or “switching off” of surface
polaritons with a fixed frequency.
Pis'ma Zh. éksp. Teor. Fiz. 68, No. 12, 876–880 (25 December 1998) 相似文献
12.
I. Gatare J. Buesa H. Thienpont K. Panajotov M. Sciamanna 《Optical and Quantum Electronics》2006,38(4-6):429-443
Bistability as well as dynamics associated to polarization switching in a vertical-cavity surface-emitting laser (VCSEL) submitted
to orthogonal optical injection from an external master laser are investigated. Intensity-polarization switching bistability
is studied by increasing and decreasing the intensity of the injected beam and for a fixed frequency detuning, i.e. the frequency
offset between master and the free running VCSEL. Depending on the frequency detuning, bistable switching is experimentally
found to occur with or without injection locking of the fundamental mode to the master laser frequency. For large positive
detuning, injection locking of the first-order transverse mode with a strong depression of the fundamental mode has been observed.
The case of frequency – polarization switching bistability, i.e. when the frequency detuning is first decreased and then increased
for a fixed injected power, has also been theoretically analyzed. Qualitative comparison with previous experimental work is
presented for the dependence of the width of the bistable switching region on the injection strength level. Finally we show
an experimental result of complicated dynamics including period doubling route to chaos that accompany polarization switching
and which motivates future theoretical investigations. 相似文献
13.
It is shown that local formation of electric charge in a region near the surface of lithium niobate crystals can take place
both by local polarization switching of the sample and by local injection of electric charge from a needle-shaped electrode.
A local change, due to the electrooptic effect, in the birefringence of the sample near the charged region is used to investigate
the nature and the formation mechanism of the charge relief.
Fiz. Tverd. Tela (St. Petersburg) 41, 510–512 (March 1999) 相似文献
14.
Theoretical studies of ultrafast ablation of metal targets dominated by phase explosion 总被引:2,自引:0,他引:2
Ultrashort pulse laser ablation of metallic targets is investigated theoretically through establishing a modified two-temperature
model that takes into account both the temperature dependent electron–lattice coupling and the electron–electron-collision
dominated electron diffusion processes for higher electron temperature regime. The electron–lattice energy coupling rate is
found to reduce only slowly with increasing pulse duration, but grow rapidly with laser fluence, implying that the melting
time of metallic materials decreases as the laser intensity increases. By taking phase explosion as the primary ablation mechanism,
the predicted dependences of ablation rates on laser energy fluences for different laser pulse widths match very well with
the experimental data. It is also found that during phase explosion the ablation rate is almost independent of the pulse width,
whereas the ablation threshold fluence increases with the pulse duration even for femtosecond pulses. These theoretical results
should be useful in having proper understanding of the ablation physics of ultrafast micromachining of metal targets.
PACS 52.50.Jm; 61.80.Az; 72.15.Cz; 79.20.Ap; 79.20.Ds 相似文献
15.
脉冲序列控制(PT)是一种离散的非线性开关变换器控制方法,具有瞬态响应快、无需补偿网络、控制电路实现简单等优点.根据控制脉冲的产生方式不同,脉冲序列控制可分为电压型脉冲序列控制(voltage-mode PT,VM-PT)和电流型脉冲序列控制(current-mode PT,CM-PT).研究表明,工作于电感电流连续导电模式(continuous conduction mode,CCM)与工作于电感电流断续导电模式(discontinuous conduction mode)的VM-PT控制开关变换器的工作特性存在明显差别,VM-PT控制CCM开关变换器存在的低频振荡现象严重影响了其稳态及瞬态性能.目前,对CM-PT控制CCM开关变换器的工作特性还未见相关报道.研究了CM-PT控制CCM开关变换器的工作特性,对其控制参数以及稳定工作域进行了分析.分析结果表明,通过参数的合理设计,虽然可以避免低频振荡现象的发生以及开关管不能正常关断的问题,但存在变换器功率范围窄的缺点.最后针对这一缺点提出了一种改进的控制方法. 相似文献
16.
A Q-switched mode-locking femtosecond all-fiber laser based on a 2 cm long homemade Er3+/Yb3+ codoped phosphate glass fiber has been reported. By using the nonlinear polarization evolution technique, a nearly 100% modulation
depth of mode-locking pulse train is achieved. At a pump power of 410 mW, the energy of each Q-switched envelope, whose width
is about 220 μs, is 10 μJ, while the duration of mode-locking pulse within the Q-switched envelope is 318-fs. 相似文献
17.
基于光子晶体光纤中脉冲俘获的超高速光开关 总被引:5,自引:4,他引:1
提出一种基于光子晶体光纤中脉冲俘获现象的超高速全光开关.信号脉冲处于正常色散区,它们彼此的时域间隔为1 ps.通过数值求解光子晶体光纤中脉冲传播满足的耦合非线性薛定谔方程,发现用孤子脉冲可俘获信号脉冲串中的任何一个脉冲,被俘获的信号脉冲的中心波长明显蓝移,在频域上和其他信号脉冲分离开来,于是让信号脉冲串在输出端通过布喇格光纤光栅,被俘获的信号脉冲将被过滤掉.数值模拟表明,用脉冲俘获实现的光开关响应速率可以达到1 THz. 相似文献
18.
We generalize the joint time–frequency von Neumann representation of femtosecond laser pulses for usage with time-dependent
polarization states. The electric field is expanded in terms of Gaussian-shaped transform-limited subpulses located on a discrete
time–frequency lattice, each with a specific polarization state. This formalism provides an intuitive picture for the time-
and frequency-dependent polarization state. It can also serve as a basis for polarization pulse shaping. As an illustration,
we define pulses for which polarization parameters (ellipticity and orientation) are given directly in time–frequency phase
space. This approach has applications in quantum control and other areas for which time- and frequency-dependent light polarization
is relevant. 相似文献
19.
C. L. Lu J. Fan H. M. Liu K. Xia K. F. Wang P. W. Wang Q. Y. He D. P. Yu J.-M. Liu 《Applied Physics A: Materials Science & Processing》2009,96(4):991-996
The magnetization, Raman spectroscopy, and ferroelectricity of multiferroic GdMn2O5 as a function of temperature and magnetic field are investigated. The complicated magnetic transitions at low temperatures
are featured with anomalous Raman mode shifts, dielectric response, and ferroelectricity generation, indicating the significant
spin–phonon coupling. It is argued that this coupling is possibly responsible for the electrical polarization generation associated
with the incommensurate–commensurate transition.
相似文献
20.
We present a relativistic model for the centrifugal acceleration of plasma bunches and the coherent radio emission in pulsar
magnetosphere. We find that rotation broadens the width of leading component compared to the width of trailing component.
We explain this difference in the component widths using the nested cone emission geometry. We estimate the effect of pulsar
spin on the Stokes parameters, and find that the inclination between the rotation and magnetic axes can introduce an asymmetry
in the circular polarization of the conal components. We analyse the single pulse polarization data of PSR B032954 at 606
MHz, and find that in its conal components, one sense of circular polarization dominates in the leading component while the
other sense dominates in the trailing component. Our simulation shows that changing the sign of the impact parameter changes
the sense of circular polarization as well as the swing of polarization angle
Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore,
India. 相似文献