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排序方式: 共有1670条查询结果,搜索用时 15 毫秒
1.
Poly (linoleic acid)-g-poly(methyl methacrylate) (PLiMMA) graft copolymer was synthesized and characterized. PLiMMA graft copolymer was synthesized from polymeric linoleic acid peroxide (PLina) possessing peroxide groups in the main chain by free radical polymerization of methyl methacrylate. Later, PLiMMA was characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. Furthermore, Au/PLiMMA/n-Si diode was fabricated for the purpose of investigating PLiMMA׳s conformity in diodes. The main electrical characteristics of this diode were investigated using experimental current–voltage (I–V) measurements in dark and at room temperature. Obtained results, such as sufficiently high rectifying ratio of 4.5×104, indicate that PLiMMA is a promising organic material for electronic device applications. 相似文献
2.
F. Prez-Willard C. Sürgers H. Von Lhneysen P. Pfundstein 《Physica E: Low-dimensional Systems and Nanostructures》2004,22(4):872-880
The electronic transport through nanostructured bismuth nanobridges has been investigated at low temperatures (T<2 K) and in magnetic fields B up to 8.5 T. The samples show reproducible resistance fluctuations as a function of B, superimposed on a large magnetoresistance of up to 50%. In addition, time-dependent resistance fluctuations in zero magnetic field demonstrate the presence of bistable scatterers in the constriction region of our samples, which are described by two-level systems. Their dynamics are shown to be sensitive to subtle modifications of the static scatterer configuration in their vicinity, which cannot be detected in the sample magnetofingerprint. 相似文献
3.
Jack Harrowfield Dominique Matt 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(3-4):133-150
The problems involved in identifying and quantifying labile interactions considered to influence complex compound structures are highlighted through the assessment of four different families of metal complexes for which extensive crystallographic data are available. Modification of the charge distribution within a ligand molecule as a result of coordination is one factor with a number of ramifications. A detailed analysis of evidence for both intra- and inter-molecular attractions in dimethylsulfoxide complexes of metal perchlorates is used to provide a basis for the consideration of weak interactions between complex ions involving forces including phenyl-group attractions, hydrogen bonding and cavity inclusion. 相似文献
4.
The GaSb layers investigated were grown directly on GaAs substrates by molecular beam epitaxy (MBE) using SnTe source as the
n-type dopant. By using admittance spectroscopy, a dominant deep level with the activation energy of 0.23-0.26 eV was observed
and its concentration was affected by the Sb4/Ga flux ratio in the MBE growth. A lowest deep-level concentration together with a highest mobility was obtained for GaSb
grown at 550°C under a Sb4/Ga beam equivalent pressure (BEP) ratio around 7, which should correspond to the lowest ratio to maintain a Sb-stabilized
surface reconstruction. In the Hall measurement, an analysis of the temperature-dependent mobility shows that the ionized
impurity concentration increases proportionally with the sample’s donor concentration, suggesting that the ionized impurity
was introduced by an SnTe source. In addition, optical properties of an undoped p-, a lightly and heavily SnTe-doped GaSb
layers were studied by comparing their photoluminescence spectra at 4.5K. 相似文献
5.
The bias dependent interface charge is considered as the origin of the observed non-ideality in current–voltage and capacitance–voltage characteristics. Using the simplified model for the interface electronic structure based on defects interacting with the continuum of interface states, the microscopic origin of empirical parameters describing the bias dependent interface charge function is investigated. The results show that in non-ideal metal–semiconductor contacts the interface charge function depends on the interface disorder parameter, density of defects, barrier pinning parameter and the effective gap center. The theoretical predictions are tested against several sets of published experimental data on bias dependent ideality factor and excess capacitance in various metal–semicoductor systems. 相似文献
6.
The article concerns heterojunction resonant cavity-enhanced (RCE) Schottky photodiodes with GaAs in the absorption layer. The quantum efficiency and linear pulse response have thoroughly been analysed. For the first time, the response of a heterojunction photodiode has been modelled by the phenomenological model for a two-valley semiconductor. The results obtained have shown that the satellite valleys, as well as the parasitic time constant, significantly influence the response and, accordingly, have to be taken into account when analysing and optimizing RCE photodetectors. 相似文献
7.
M. Dubé C. Daneault V. Vuorinen M. Alava M. Rost 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):15-26
We investigate the structure and dynamics of the interface between
two immiscible liquids in a three-dimensional disordered porous
medium. We apply a phase-field model that includes explicitly
disorder and discuss both spontaneous and forced imbibition.
The structure of the interface is dominated by a length scale
ξ× which arises from liquid conservation. We further show
that disorder in the capillary and permeability act on different
length scales and give rise to different scalings and
structures of the interface properties. We conclude with a
range of applications. 相似文献
8.
We have proposed a mechanism of nonideality, i.e., the temperature dependence of the ideality factor, in nearly ideal Au/n-Si Schottky barriers. Because of the nature of metal-induced gap states, positively ionized defects close to the interface are considered to cause local lowering of the Schottky barrier height (SBH) due to downward bending of the energy band. These positively charged defects become neutralized in equilibrium with the Fermi level due to the band bending, when they are very close to the interface. However, because the SBH lowering disappears by the neutralization of donor, the energy level of donor with a usual energy level scheme rises above the Fermi level after the neutralization. This contradiction to the equilibrium neutralization is resolved by Si self-interstitial with a large negative-U property, which is generated by the fabrication process. The energy level of the donor estimated from the SBH lowering is in good agreement with that of theoretical calculation of Si self-interstitial. Thus, the defect is concluded to be the Si self-interstitial, which is distributed to more than 10 Å depth from the interface. 相似文献
9.
Pd-Ge based ohmic contact to n-GaAs with a TiW diffusion barrier was investigated. Electrical analysis as well as Auger electron
spectroscopy and the scanning electron microscopy were used to study the contact after it was subjected to different furnace
and rapid thermal annealing and different aging steps. All analyses show that TiW can act as a good barrier metal for the
Au/Ge/Pd/n-GaAs contact system. A value of 1.45 × 10−6 Ω-cm2 for the specific contact resistance was obtained for the Au/TiW/Ge/Pd/n-GaAs contact after it was rapid thermally annealed
at 425°C for 90 s. It can withstand a thermal aging at 350°C for 40 h with its ρc increasing to 2.94 × 10−6Ω-cm2 and for an aging at 410°C for 40 h with its ρc increasing to 1.38 × 10−5 Ω-cm2. 相似文献
10.
High-temperature isothermal capacitance transient spectroscopy (H-ICTS) measurements were conducted to characterize near mid-gap defects, which are the origin of the memory effect in Ni/p-GaN Schottky contacts. A large single peak was detected only under the forward bias conditions. This indicates that the defects were located in the vicinity of the interface. The change of the peak height and position of the ICTS curves under various bias conditions were qualitatively interpreted by the distribution of the defects and the current flow effect. 相似文献