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341.
Ling-Feng Mao 《Applied Surface Science》2008,254(20):6628-6632
The effects of the interface defects on the gate leakage current have been numerically modeled. The results demonstrate that the shallow and deep traps have different effects on the dependence relation of the stress-induced leakage current on the oxide electric field in the regime of direct tunneling, whereas both traps keep the same dependence relation in the regime of Fowler-Nordheim tunneling. The results also shows that the stress-induced leakage current will be the largest at a moderate oxide voltage for the electron interface traps but it increases with the decreasing oxide voltage for the hole interface traps. The results illustrate that the stress-induced leakage current strongly depends on the location of the electron interface traps but it weakly depends on the location of the hole interface traps. The increase in the gate leakage current caused by the electron interface traps can predict the increase, then decrease in the stress-induced leakage current, with decreasing oxide thickness, which is observed experimentally. And the electron interface trap level will have a large effect on the peak height and position. 相似文献
342.
We report the discovery that the low-temperature magnetic relaxation in Mn12Ac single crystals strongly depends on the shape of the samples. The relaxation time exhibits a minimum at the phase transition point between ferromagnetic and antiferromagnetie phases. The shape dependence is attributed to the dipolar interaction between molecular magnets. 相似文献
343.
Ultra-sensitive mid-infrared cavity leak-out spectroscopy using a cw optical parametric oscillator 总被引:1,自引:0,他引:1
A. Popp F. Müller F. Kühnemann S. Schiller G. von Basum H. Dahnke P. Hering M. Mürtz 《Applied physics. B, Lasers and optics》2002,75(6-7):751-754
We report a portable, all-solid-state, mid-infrared spectrometer for trace-gas analysis. The light source is a continuous-wave
optical parametric oscillator based on PPLN and pumped by a Nd:YAG laser at 1064 nm. The generated single-frequency idler
output covers the wavelength region between 2.35 and 3.75 μm. With its narrow line width, this light source is suitable for
precise trace-gas analysis with very high sensitivity. Using cavity leak-out spectroscopy we achieved a minimum detectable
absorption coefficient of 1.2×10-9 /cm (integration time: 16 s), corresponding, for example, to a detection limit of 300 parts per trillion ethane. This sensitivity
and the compact design make this trace-gas analyzer a promising tool for various in situ environmental and medical applications.
Received: 19 September 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-228/733-474, E-mail: frank.kuehnemann@iap.uni-bonn.de 相似文献
344.
We have studied the adsorption of neutral polyampholytes on model charged surfaces that have been characterized by contact
angle and streaming current measurements. The loop size distributions of adsorbed polymer chains have been obtained using
atomic-force microscopy (AFM) and compared to recent theoretical predictions. We find a qualitative agreement with theory;
the higher the surface charge, the smaller the number of monomers in the adsorbed layer. We propose an original scenario for
the adsorption of polyampholytes on surfaces covered with both neutral long-chain and charged short-chain thiols.
Received 22 February 2002 and Received in final form 23 April 2002 相似文献
345.
A. Sacchetti 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):229-232
Here we consider the dynamics of a two-level system under an external time-dependent field. We show that in the case of a
bichromatic field the dynamical localization effect is strongly sensitive with respect to the commensurability of the driving
frequencies.
Received 8 May 2002 / Received in final form 4 July 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: Sacchetti@unimo.it 相似文献
346.
The surface layer effects on transport in epitaxial La2/3Ca1/3MnO3 thin films are studied. It was found that the two-probe resistance is nonlinear which is enhanced with decreasing temperature. Similar to the resistance of intrinsic La2/3Ca1/3MnO3 thin films reported in the literature, the apparent dynamic contact resistance behaves semiconducting at high temperatures, passes through a peak, and displays a metallic behavior. At lowest temperatures, the curve of the contact resistance versus temperature shows a little upturn. The temperature dependent work function difference between the surface layer and the thin film underneath, together with the tunneling process across either the resulting charge depleted layer or the semiconducting surface layer is used to explain our observations. 相似文献
347.
The La0.8Sr0.2MnO3 (LSMO)/ TiO2 heterostructures with different thicknesses of the LSMO films were successfully synthesized using the RF magnetron sputtering technique. Excellent rectifying characteristics are presented in all heterostructures in a wide temperature range. The differences of the diffusive potentials for three heterojunctions are very little at 300 K. The samples exhibit a high resistance that plays an important role on their rectifying properties. The diffusive potential decreases with increasing temperature. The result is attributed to both the reduction of the thickness of the deletion layer due to the thermal diffusion and the modulation of the interfacial electronic structure of the heterostructures. The metal-insulator (M-I) transition is observed clearly from the single LSMO layers and the LSMO/ TiO2 p-n heterojunctions. 相似文献
348.
We report the detailed results of magnetization and magnetoresistance measurements in the Ru doped layered manganite system La1.2Sr1.8Mn2−xRuxO7 (x=0, 0.1, 0.5, 1.0). High-resolution measurements of magnetization and magnetoresistance were carried out as functions of temperature, magnetic field and time. We find evidence for the existence of competing ferromagnetic and antiferromagnetic interactions resulting in the formation of a frustrated spin-glass-like state at low temperatures. The time dependent magnetization follows the relation very well. We find that Ru doping enhances the coercive field and drives the system towards a magnetically mixed phase at low temperatures. Large negative magnetoresistance values are observed in all samples and at low temperatures the magnetoresistance varies as the square root of the applied magnetic field. 相似文献
349.
A.?V.?Sarantsev V.?A.?Nikonov A.?V.?Anisovich E.?KlemptEmail author U.?Thoma 《The European Physical Journal A - Hadrons and Nuclei》2005,25(3):441-453
Cross-sections, beam asymmetries, and recoil polarisations for the reactions γp → K
+Λ;γp → K
+Σ0, and γp → K
0Σ+ have been measured by the SAPHIR, CLAS, and LEPS Collaborations with high statistics and good angular coverage for centre-of-mass
energies between 1.6 and 2.3 GeV. The combined analysis of these data with data from π and η photoproduction reveals evidence
for new baryon resonances in this energy region. A new P11 state with mass 1840 MeV and width 140 MeV was observed contributing to most of the fitted reactions. The data demand the
presence of two D13 states at 1875 and, optimistically, at 2170 MeV. 相似文献
350.
Ionization of metal clusters by ions in the Fermi velocity range 总被引:1,自引:0,他引:1
P.G. Reinhard E. Suraud C.A. Ullrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):303-311
We simulate excitation of metal clusters by highly charged, energetic ions, analyzing electron emission in terms of discrete
ionization probabilities. Our test case is the collision of on the cluster at velocities around the electronic Fermi velocity of bulk sodium. The calculations are performed with a density-functional
approach, using the time-dependent local density approximation. We find that ionization takes place on an extremely short
time scale of less than 5 fs. The preferred final charge state depends sensitively on the impact parameter. High ionization
can easily be achieved in sufficiently close collisions. Direct trapping through the by-passing ion is found to be of little
importance at the velocities considered.
Received: 28 July 1997 / Received in final form: 23 December 1997 / Accepted: 8 January 1998 相似文献