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901.
J. C. Zolper J. Han R. M. Biefeld S. B. van Deusen W. R. Wampler D. J. Reiger S. J. Pearton J. S. Williams H. H. Tan R. F. Karlicek Jr. R. A. Stall 《Journal of Electronic Materials》1998,27(4):179-184
Implant activation annealing of Si-implanted GaN is reported for temperatures from 1100 to 1400°C. Free electron concentrations
up to 3.5×1020 cm−3 are estimated at the peak of the implanted profile with Hall mobilities of ∼60 cm2/Vs for annealing at 1300°C for 30 s with an AIN encapsulant layer. This mobility is comparable to epitaxial GaN doped at
a similarly high level. For annealing at ≥1300°C, the sample must be encapsulated with AIN to prevent decomposition of the
GaN layer. Channeling Rutherford backscattering demonstrates the partial removal of the implant damage after a 1400°C anneal
with a minimum channeling yield of 12.6% compared to 38.6% for the as-implanted spectrum. Scanning electron microscope images
show evidence of decomposition of unencapsulated GaN after a 1300°C anneal and complete sublimation after 1400°C. The use
of AIN encapsulation and annealing at temperatures of ∼1300°C will allow the formation of selective areas of highly doped
GaN to reduce the contact and access resistance in GaN-based transistors and thyristors. 相似文献
902.
用第一性原理基础上的超软赝势方法的总能计算,研究了3d过渡金属(Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn)在Pd(001)表面的单层p(1×1)和c(2×2)结构的表面磁性和总能. 所得结果表明:对于Sc, Ti, V和Cr只存在p(1×1)的铁磁性结构,而Mn只有c(2×2)的反铁磁结构存在. Fe, Co和Ni这三种元素上述两种结构都存在,但是总能上p(1×1)的铁磁结构要低些,因此是比较稳定的结构. 而Cu和Zn在该表面上的单层中不存在上述两种结构. 对于V的p(1×1)铁磁结构,计算得到的每个V原子磁矩为2.41μB,大于用全电子方法得到的0.51μB. 两种计算方法得到其他金属原子 (Cr,Mn,Fe,Co,Ni)的表面磁矩比较相近,都比孤立原子磁矩略小.
关键词:
Pd(001)表面
过渡金属原子单层
表面磁性 相似文献
903.
大气光通信中大气闪烁时间平滑效应研究 总被引:4,自引:1,他引:3
利用大气闪烁的时间平滑效应,增加光电探测器曝光时间是克服大气闪烁对大气光通信的瞄准、捕获、跟踪链路影响的有效途径之一.基于科尔莫戈罗夫谱,导出了弱湍流起伏区无限平面波和球面波的大气闪烁时间平滑因子的一般表达式,并且用几何光学近似得到了在大孔径和小孔径接收情况下的时间平滑因子近似表达式.在孔径远大于菲涅耳区尺度时,平面波和球面波的时间平滑因子的近似表达式与精确表达式的误差分别小于6%和3%.分析结果表明,孔径越小,时间平滑效应越显著,并且菲涅耳区尺度对时间平滑效应影响的程度也随着孔径的增加而减弱. 相似文献
904.
Tan PH Rozhin AG Hasan T Hu P Scardaci V Milne WI Ferrari AC 《Physical review letters》2007,99(13):137402
We investigate photoluminescence of nanotube bundles. Their spectra are explained by exciton energy transfer between adjacent tubes, whereby excitation of large gap tubes induces emission from smaller gap ones. The consequent relaxation rate is faster than nonradiative recombination, leading to enhanced photoluminescence of acceptor tubes. 相似文献
905.
A hybrid cavity magnomechanical system to transfer the bipartite entanglements and achieve the strong microwave photon–phonon entanglement based on the reservoir engineering approach is constructed. The magnon mode is coupled to the microwave cavity mode via magnetic dipole interaction and to the phonon mode via magnetostrictive force (optomechanical-like). It is shown that the initial magnon-phonon entanglement can be transferred to the photon-phonon subspace in the case of these two interactions cooperating. In the reservoir-engineering parameter regime, the initial entanglement is directionally transferred to the photon-phonon subsystem, so a strong bipartite entanglement in which the magnon mode acts as the cold reservoir to effectively cool the Bogoliubov mode delocalized over the cavity and the mechanical deformation mode is obtained. Moreover, dual-mode cooling is realized by engineering the dissipation of photon and phonon modes within the target mode, which allows entanglement to be further enhanced. The results indicate that the steady-state entanglement is robust against temperature. The dual-mode cooling reservoir engineering scheme can potentially be extended to other three-mode quantum systems. 相似文献
906.
Zi-Long Li Xing-Yue Tan Zhu-Feng Zhang Zhen-Yang Wang Xin-Heng Guo 《中国物理C(英文版)》2023,47(1):013102-013102-8
In this study, we systematically investigated two-pseudoscalar meson systems with the Bethe-Salpeter equation in the ladder and instantaneous approximations. By solving the Bethe-Salpeter equation numerically with the kernel containing the one-particle exchange diagrams, we found that the \begin{document}$ K\bar{K} $\end{document} ![]()
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, \begin{document}$ DK $\end{document} ![]()
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, \begin{document}$ B\bar{K} $\end{document} ![]()
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, \begin{document}$ D\bar{D} $\end{document} ![]()
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, \begin{document}$ B\bar{B} $\end{document} ![]()
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, \begin{document}$ BD $\end{document} ![]()
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, \begin{document}$ D\bar{K} $\end{document} ![]()
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, \begin{document}$ BK $\end{document} ![]()
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, and \begin{document}$ B\bar{D} $\end{document} ![]()
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systems with \begin{document}$ I=0 $\end{document} ![]()
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can exist as bound states. We also studied the contributions from heavy meson (\begin{document}$ J/\psi $\end{document} ![]()
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and \begin{document}$\Upsilon $\end{document} ![]()
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) exchanges and found that the contributions from heavy meson exchanges cannot be ignored. 相似文献
907.
He Xiaobo Li Yuke Zeng Hai Zhu Zengwei Tan Shiyong Zhang Yongjun Cao Chao Luo Yongkang 《中国科学:物理学 力学 天文学(英文版)》2023,66(3):1-10
Science China Physics, Mechanics & Astronomy - The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest and most sensitive single-dish radio telescope in the world and... 相似文献
908.
We investigate the effects of long-range interactions on the spin wave spectra and the competition between magnetic phases on a frustrated square lattice with large spin S. Applying the spin wave theory and assisted with symmetry analysis, we obtain analytical expressions for spin wave spectra of competing Neel and (π, 0) stripe states of systems containing any-order long-range interactions. In the specific case of long-range interactions with power-law decay, we find surprisingly that the staggered long-range interaction suppresses quantum fluctuation and enlarges the ordered moment, especially in the Neel state, and thus extends its phase boundary to the stripe state. Our findings illustrate the rich possibilities of the roles of long-range interactions, and advocate future investigations in other magnetic systems with different structures of interactions. 相似文献
909.
910.
圆柱壳的动态塑性屈曲问题的研究主要是集中在屈曲模态方面,至于屈曲的临介载荷与临介时时间则研究的较少,SHPB用于研究材料在高应变率下动态力学性能已为大家所熟悉,但用于研究结构的动态屈曲则未见报道,本文利用一装置对柱壳的动态塑性屈曲进行了实验研究,测出了壳体屈曲过程的载荷,轴向缩短量与时间的关系曲线,得到屈曲时的临介载荷与临介时间,同时发现壳体屈曲变形的一些规律并与静态实验的结果进行了比较,为理论分 相似文献