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半导体材料及其光电器件如激光器、探测器以及高速微波器件有着广阔的应用前景。半导体材料的结构和缺陷特性对器件性能起着至关重要的影响,然而对材料进行纳米尺度下的检测、表征无论是理论上还是技术和设备上都需要深入研究和发展,因此扫描近场光学显微技术在半导体材料表征领域有着无可替代的地位。扫描近场光学显微技术突破了传统光学显微技术的衍射分辨率极限的限制,具有超高空间分辨率、超高探测灵敏度等特点,并且是一种非接触性探测,具有无损伤性。简要介绍了扫描近场光学显微镜的原理及在半导体材料研究中的应用,包括量子阱结构中的位错及缺陷的表征,半导体器件的表面复合速率及扩散长度的纳米表征,以及半导体薄膜中的缺陷分布的检测。探讨了目前相关研究领域存在的主要问题,并对其发展趋势和前景进行了展望。 相似文献
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半导体材料是现代科技发展和产业革新的核心,随着高频、高压、高温、高功率等工况的日趋严峻及“双碳”目标的需要,以新型碳化硅(SiC)和氮化镓(GaN)等为代表的第三代半导体材料逐步进入工业应用。半导体产业的贯通以及市场规模的快速扩大,导致摩尔定律正逐渐达到极限,先进封装互连将成为半导体行业关注的焦点。第三代半导体封装互连材料有高温焊料、瞬态液相键合材料、导电胶、低温烧结纳米Ag/Cu等几个发展方向,其中纳米Cu因其优异的导电导热性、低温烧结特性和良好的可加工性成为一种封装互连的新型方案,具有低成本、高可靠性和可扩展性,近年来从材料研究向产业链终端应用贯通的趋势非常明显。本文首先介绍了半导体材料的发展概况并总结了第三代半导体封装互连材料类别;然后结合近期研究成果进一步围绕纳米Cu低温烧结在封装互连等电子领域中的应用进行重点阐述,主要包括纳米铜粉的粒度、形貌、表面处理和烧结工艺对纳米铜烧结体导电性能和剪切性能的影响;最后总结了目前纳米铜在应用转化中面临的困境和亟待解决的难点,并展望了未来的发展方向,以期为低温烧结纳米铜领域的研究提供参考。 相似文献
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详细介绍了硅化物环境半导体材料的理论计算和实验研究进展,主要包括β-FeSi_2、ca_2Si、CrSi_2等硅化物的新的光电特性及理论计算结果,并对硅化物环境半导体材料在光电子领域的应用进行了讨论。 相似文献
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基于密度泛函理论的第一性原理,计算了锰原子单空位掺杂锯齿型石墨烯纳米带6种不同位置时的电磁学特性。结果表明:锰原子掺杂石墨烯纳米带的能带结构对掺杂位置十分敏感。随着锰掺杂位置的变化,掺杂石墨烯纳米带分别表现出半导体性和金属性特征。锰原子掺杂石墨烯纳米带改变了原本的磁性特征,掺杂位置不同,结构磁性特点也不相同,掺杂位置在4号位置时,纳米带实现了由反铁磁态的锯齿型石墨烯纳米带向铁磁性的转化。锰原子掺杂锯齿型石墨烯纳米带可以调制其磁性和能带特性,为石墨烯纳米带在电磁学领域应用提供一定的理论依据。 相似文献
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基于密度泛函理论的第一性原理,计算了锰原子单空位掺杂锯齿型石墨烯纳米带6种不同位置时的电磁学特性。结果表明:锰原子掺杂石墨烯纳米带的能带结构对掺杂位置十分敏感。随着锰掺杂位置的变化,掺杂石墨烯纳米带分别表现出半导体性和金属性特征。锰原子掺杂石墨烯纳米带改变了原本的磁性特征,掺杂位置不同,结构磁性特点也不相同,掺杂位置在4号位置时,纳米带实现了由反铁磁态的锯齿型石墨烯纳米带向铁磁性的转化。锰原子掺杂锯齿型石墨烯纳米带可以调制其磁性和能带特性,为石墨烯纳米带在电磁学领域应用提供一定的理论依据。 相似文献
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ZnO是一种可用于室温或更高温度下的紫外发光材料,纳米结构的ZnO(如单晶薄膜、纳米粒子膜、纳米线和纳米带等)则更是在紫外激光发射领域显示了独到的优势,被认为是有望构造短波长半导体激光器的理想材料.本文对一维ZnO纳米结构(纳米线、纳米管和纳米带)的真空物理气相沉积制备技术及生长机理进行了初步探讨. 相似文献
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Electronic Structure Control of Tungsten Oxide Activated by Ni for Ultrahigh‐Performance Supercapacitors 下载免费PDF全文
Tian Meng Zongkui Kou Ibrahim Saana Amiinu Xufeng Hong Qingwei Li Yongfu Tang Yufeng Zhao Shaojun Liu Liqiang Mai Shichun Mu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
Tuning the electron structure is of vital importance for designing high active electrode materials. Here, for boosting the capacitive performance of tungsten oxide, an atomic scale engineering approach to optimize the electronic structure of tungsten oxide by Ni doping is reported. Density functional theory calculations disclose that through Ni doping, the density of state at Fermi level for tungsten oxide can be enhanced, thus promoting its electron transfer. When used as electrode of supercapacitors, the obtained Ni‐doped tungsten oxide with 4.21 at% Ni exhibits an ultrahigh mass‐specific capacitance of 557 F g?1 at the current density of 1 A g?1 and preferable durability in a long‐term cycle test. To the best of knowledge, this is the highest supercapacitor performance reported so far in tungsten oxide and its composites. The present strategy demonstrates the validity of the electronic structure control in tungsten oxide via introducing Ni atoms for pseudocapacitors, which can be extended to other related fields as well. 相似文献
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Negative differential resistance (NDR) was recently observed in carbon nanotube junctions just before breaking and hypothesized to arise from the formation of monatomic carbon wires in the junction. Motivated by these results, a first-principles scattering-state approach, based on density functional theory, is used to study the transport properties of carbon chains covalently connecting metallic carbon nanotube leads at finite bias. The I- V characteristics of short carbon chains are predicted to exhibit even-odd behavior, and NDR is found for both even and odd chain junctions in our calculations. 相似文献
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本研究采用基于密度泛函理论的第一性原理方法, 在局域密度近似和广义梯度近似下, 研究了单点缺陷下不同结构氧化石墨烯的电子结构和光学特性。研究结果表明: 文中四种构型的氧化石墨烯为力学稳定结构, 其中包含不饱和氧原子的氧化石墨烯结构在水裂解及制氢中具有重要应用潜力。能带及分波态密度计算结果表明, 包含不饱和氧原子的构型为间接带隙半导体, 其余构型均为直接带隙半导体, 且掺杂类型和带隙值随结构不同而改变。氧化石墨烯的光学吸收表现为各向异性, 且在垂直于平面方向上的吸收边蓝移到近紫外可见光区。包含sp 3杂化形式的结构光学吸收系数比包含sp 2杂化的结构高, 说明碳氧双键和悬挂键的存在对吸收光谱有重要影响。 相似文献
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We review the state of first-principles density functional theory (DFT) modeling of nuclear fuel materials. DFT-based first-principles modeling has emerged as a quantitatively rigorous method that has been widely used to study these materials. The main challenge in DFT modeling of nuclear fuels lies in the f electron nature of actinide materials. DFT + U methods along with regular DFT methods including both non-spin-polarized and spin-polarized treatments are discussed. The review topics include bulk and intrinsic defects properties, stability of fission products, modeling of fission gas (xenon) transport, and non-equilibrium behavior of fission products in uranium dioxide and surrogate materials. In addition, DFT modeling activity in alternative fuel forms including uranium nitride, uranium carbide, and metal fuels is reviewed. Some of the limitations of empirical potential calculations addressed by DFT are also discussed. 相似文献
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From first-principles calculations, we predict a planar stable graphene allotrope composed of a periodic array of tetragonal and octagonal (4, 8) carbon rings. The stability of this sheet is predicted from the room-temperature molecular dynamics study and the electronic structure is studied using state-of-the-art calculations such as the hybrid density functional and the GW approach. Moreover, the mechanical properties of (4, 8) carbon sheet are evaluated from the Young's modulus and intrinsic strength calculations. We find this is a stable planar semiconducting carbon sheet with a bandgap between 0.43 and 1.01?eV and whose mechanical properties are as good as graphene's. 相似文献
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We report first-principles calculations of the structural, lattice-dynamical and dielectric properties for zinc-blend beryllium chalcogenides: BeS, BeSe, and BeTe. The ground state properties, such as the lattice structure and bulk modulus, are calculated using a plane wave pseudopotential method within the density functional theory. A linear response approach is employed in order to derive the high-frequency dielectric constants, Born effective charges and phonon frequencies. Furthermore, the pressure dependence of phonon modes is also detailed. 相似文献
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Multishell Carrier Transport in Multiwalled Carbon Nanotubes 总被引:1,自引:0,他引:1
Agrawal S. Raghuveer M.S. Ramprasad R. Ramanath G. 《Nanotechnology, IEEE Transactions on》2007,6(6):722-726
Understanding carrier transport in carbon nanotubes (CNTs) and their networks is important for harnessing CNTs for device applications. Here, we report multishell carrier transport in individual multiwalled CNTs, and films of randomly dispersed multiwalled CNTs, as a function of electric field and temperature. Electrical measurements and first-principles density functional theory calculations indicate transport across CNT shells. Intershell conduction occurs across an energy barrier range of 60-250 meV in individual CNTs, and ~ 60 meV in CNT networks. In both cases, the conductance behavior can be explained based upon field-enhanced carrier injection and defect-enhanced transport, as described by the Poole-Frenkel model. 相似文献