Novel laminated multiferroic heterostructures for reconfigurable microwave devices

Voltage tuning of magnetism is fundamentally and technically important for fast, compact and ultra-low power electronic devices. Multiferroic heterostructures,simultaneously exhibiting distinct ferroelectric and ferromagnetic properties, have caught a lot of attentions because of the capability of controlling magnetism by a voltage via a strain-mediated magnetoelectric（ME） coupling. In these materials, a voltage-induced strain is involved to create an effective magnetic field and change ferromagnetic resonance frequency in the coupled ferromagnetic phases through magnetoelastic interactions. Therefore, the devices made of such materials are compact, ultra-fast and energy efficient,providing new functionalities for microwave components.This paper will review the recent progress of multiferroics and their applications in microwave devices from different aspects, including the creation of the novel laminated multiferroic heterostructures with a strong ME coupling, the realization of the multiferroics based on tunable microwave signal processors and the investigation of nonvolatile tuning of microwave properties using ferroelastic domain switching in multiferroic heterostructures. These tunable multiferroic heterostructures and devices offer great opportunities for realizing the next generation of tunable magnetic microwave components, ultra-low power electronics and spintronics.     

非故意掺杂与半绝缘GaN缓冲层上的AlGaN/GaN异质结构的高温电子输运特性

研究了非故意掺杂(UID)与半绝缘(SI)GaN缓冲层(BL)上的Al0.35Ga0.65N/GaN异质结构高温下的电子输运特性,应用Hall效应系统地测量了样品在高温下的电子面密度和电子迁移率随温度变化的关系.实验发现,高温下AlGaN/GaN异质结构的电子迁移率主要受到LO声子散射的作用,其中,UID-BL样品的电子面密度随温度升高而逐渐上升,SI-BL样品的电子面密度则随温度升高呈现先下降再平衡后上升的规律.对相应的未生长AlGaN势垒层的本征GaN薄膜的高温电阻特性分析表明,随着温度的升高,UID-BL样品的电子迁移率受到背景载流子的影响逐渐增大;SI-BL样品的电子迁移率在室温附近受附加位错散射的影响较大,600K以后受背景载流子的影响缓慢增强,这对于研究AlGaN/GaN异质结构器件的高温特性具有很好的参考意义.另外,由理论计算可知,高温下二维电子气(2DEG)逐渐向势垒层和缓冲层内部扩展,电子在第一子带的占据从室温下的86%下降到700K时的81%.     

Tunable multiple-channel filters based on photonic heterostructures using single-negative materials

We studied the multiple-channel filters based on photonic heterostructures consisting of single-negative permittivity and single-negative permeability media. The results showed that the number of resonance modes inside the zero-φeff gap increases as the number of heterogenous interface M increases. The number of resonance modes inside the zero-φeff, gap is equal to that of heterogenous interface M, and it can be used as M channels filter. This result provides a feasible method to adjust the channel number of multiple-channel filters. When losses are involved, the results showed that the electric fields of the resonance modes decay largely with the increase of the number of heterogenous interface and damping factors. Besides, the relationship between the quality factor of multiple-channel filters and the number of heterogenous interface M is linear, and the quality factor of multiple-channel filters decreases with the increase of the damping factor. These results provide feasible methods to adjust the quality factor of multiple-channel filters.     

The Novel Semiconductor Nanowire Heterostructures

1 Results If one-dimensional heterostructures with a well-defined compositional profile along the wire radial or axial direction can be realized within semiconductor nanowires, new nano-electronic devices,such as nano-waveguide and nano-capcipator, might be obtained. Here,we report the novel semiconducting nanowire heterostructures:(1) Si/ZnS side-to-side biaxial nanowires and ZnS/Si/ZnS sandwich-like triaxial nanowires[1],(2) Ga-Mg3N2 and Ga-ZnS metal-semiconductor nanowire heterojunctions[2-3]and (3) ...     

对称纤锌矿结构量子阱中的准受限声子及电声相互作用的哈密顿量

在介电连续模型下,得出多层对称纤锌矿结构异质结、量子阱中的准受限声子的P-本征极化模,色散关系和电子与准受限声子相互作用的哈密顿量.此结论具有普遍的意义,对进一步研究纤锌矿结构异质结、量子阱中的准受限声子及其电声耦合强度,具有一定的理论价值.     

双势垒异质结构中自旋相关的散粒噪声

利用Landauer-Büttiker散射理论和传递矩阵方法研究了两端具有铁磁接触的双势垒异质结构(F/DB/F)中自旋相关的散粒噪声。计算结果表明:电流和散粒噪声随阱宽的增加发生周期性的振荡,随着垒厚的增加产生了明显的相位差,与自旋向上电子相比,垒厚对自旋向下电子的电流和散粒噪声影响更大。Rashba自旋轨道耦合强度的增加加大了电流和散粒噪声的振荡频率。偏压的增加减小了电流和散粒噪声的振荡频率,增大了电流和散粒噪声的峰谷比和峰值。电流和散粒噪声随自旋轨道耦合强度和偏压的变化强烈依赖于两铁磁电极中磁化方向的夹角。     

蛋白石薄膜及其异质结构的可控制备

利用毛细管辅助沉积方法制备了厚度及膜内裂缝的形状、分布可控的三维蛋白石薄膜。讨论了所得薄膜光学性质以及膜的形态特性与薄膜厚度之间的关系。用同样的方法制备了由不同粒径的球体基元晶体带构成的横向交替异质结构。     

Novel Approach to the Design of Optoelectronic Heterostructures Based on Indium and Copper Sulfides

1 Results Heterostructures,based on ternary CuInS(Se2) chalcogenides and related binary compounds (Cu2-xCh,CuCh,In2Ch3 and InCh; Ch=S,Se) are considered appear to be a matter of choice for producing promising optoelectronic devices.In the present work we propose and consider a very simple way for the formation of sulfide and selenide heterostructures.The main idea is assumes a novel two-stage method of synthesis and nonstoichiometry control for heterostructures of InxS(Se)1-x/Si,CuInS(Se)2/Si and InxS1-...     

半导体球形异质结中界面光学声子及电声相互作用

在介电连续模型下,运用传递矩阵的方法研究多层球形异质结中的界面光学声子,得出了多层球形异质结中的界面光学声子的本征模解、色散关系和电子与界面光学声子相互作用的哈密顿.对5层球形异质结CdS/HgS/CdS/HgS/H2O中的界面声子的色散关系和电声相互作用的耦合强度进行了数值计算,结果发现在5层球形异质结中,存在着7支光学界面声子,但仅有一支界面声子对电声相互作用的耦合强度具有重要的影响.     

有限单量子阱结构中电子—界面光学声子相互作用

本文给出了有限单量子阱结构中电子与有（界）面光学声子相互作用的类弗留里希哈密顿算符，电子－声子耦合函数被计算和讨论。