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The Ti electrode was deposited on the(0001) face of an n-type 4H-SiC substrate by magnetron sputtering. The effect of the electrode placement method during the annealing treatment on the contact property was carefully investigated. When the electrode was faced to the Si tray and annealed, it showed ohmic behavior, otherwise it showed a non-ohmic property.X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM), and atomic force microscopy(AFM) were used to characterize the electrode phase, composition, thickness, and surface morphology. The additional silicon introduced from the Si tray played a key role in the formation of the ohmic contact on the Ti/4H-SiC contact. 相似文献
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图映射的吸引中心与拓扑熵 总被引:2,自引:0,他引:2
设f是图G上的连续自映射,P(f),AГ(f),ω(f),Ω(f),sα(y,f)分别表示f的周期点集,单侧γ-极限点集,ω-极限集,非游荡集,相对于y的特殊α-极限点集.本文证明了:(1)x∈sα(y,f)(对某个y∈G)当且仅当x∈sα(x,f)(2)AГ(f)∪P(f)包含∪y∈Gsα(y,f)(3)AГ(f)∪P(f)=ω(Ω(f))=ω(ω(f))=ω(∪y∈Gsα(y,f))=ω(∪(AГ(f)∪P(f)).此外,本文还得到了,具有正拓扑熵的几个等价条件。 相似文献
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CRYSTALLINE CARBON NITRIDE THIN FILMS DEPOSITED BY MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION 下载免费PDF全文
The crystalline carbon nitride thin films have been prepared on Si (100) substrates using microwave plasma chemical vapor deposition technique. The experimental X-ray diffraction pattern of the films prepared contain all the strong peaks of α-C3N4 and β-C3N4, but most of the peaks are overlapped.The films are composed of α-C3N4 and β-C3N4. The N/C atomic ratio is close to the stoichiometric value 1.33. X-ray photoelectron spectroscopic analysis indicated that the binding energies of C 1s and N 1s are 286.43eV and 399.08 eV respectively. The shifts are attributed to the polarization of C-N bond. Both observed Raman and Fourier transform infrared spectra were compared with the theoretical calculations. The results support the existence of C-N covalent bond in α- and β-C3N4 mixture. 相似文献
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In this article, we discuss some properties of a supersymmetric invariant bilinear form on Lie supertriple systems. In particular, a supersymmetric invariant bilinear form on Lie supertriple systems can be extended to its standard imbedding Lie superalgebras. Furthermore, we generalize Garland's theory of universal central extensions for Lie supertriple systems following the classical one for Lie superalgebras. We solve the problems of lifting automorphisms and lifting derivations. 相似文献