Sliding <Emphasis Type="Italic">Z</Emphasis>-pinch

New devices are proposed for producing self-contracting discharges. The operation principle of these devices is based on focusing of plasma sliding over the insulator surface, when the magnetic field of the sliding discharge itself presses the plasma channel to the surface and focuses it. One of the proposed devices with an insulator in the form of a dihedral angle is studied experimentally. X-rays are detected and an X-ray image of the focused plasma is formed.     

基于AlN声表面波滤波传感器器件的有限元仿真

声表面波器件是一种利用压电材料的压电效应与逆压电效应工作电子器件, 文章首先详细描述了声表面波器件的设计与仿真过程,运用有限元分析的方法分别计算了利用声表面波的 SAW 器件与利用体波的 BAW 器件的性能与各项参数,对相关的器件进行了计算分析,分别用上述方法研究了基于 AlN 薄膜的声表面波器件和悬臂梁结构的体波器件,推导得出了器件的电学导纳与频率之间的关系, 通过分析器件的导纳-频率曲线,推导出器件内部声波的模式以及合适的工作频率,最终得出在 IDT 周期为 8 微米的情况下,SAW 器件的理想工作频率是 0.7-1.95GHz,BAW 器件的理想工作频率在 0.6-3.2GHz 的结果。     

Broadly tunable one-way terahertz plasmonic waveguide based on nonreciprocal surface magneto plasmons

One-way-propagating broadly tunable terahertz plasmonic waveguide at a subwavelength scale is proposed based on a metal-dielectric-semiconductor structure. Unlike other one-way plasmonic devices that are based on interference effects of surface plasmons, the proposed one-way device is based on nonreciprocal surface magneto plasmons under an external magnetic field. Theoretical and simulation results demonstrate that the one-way-propagating frequency band can be broadly tuned by the external magnetic fields. The proposed concept can be used to realize various high performance tunable plasmonic devices such as isolators, switches and splitters for ultracompact integrated plasmonic circuits.     

Tunable On‐Chip Sources with Aperiodic Metasurface

Surface plasmons show tremendous capability in integrated communication, quantum computing and sensing. Excitations and manipulations of surface plasmons are essential in developing integrated photonic devices. Here, a systematic study of tunable emission of surface plasmons with an eightfold quasicrystal metasurface, which acts as an on‐chip source, is presented. It is shown that the quasicrystal structure can switch on or off the surface plasmons propagation channels in the desired direction. Meanwhile, such a quasicrystal structure can be polarization‐dependent or polarization‐independent based on different constituent slit pairs. The proposed quasicrystal design provides more freedom for steering surface plasmons in the launching process. Thus, it may significantly simplify the design and fabrication of integrated plasmonic devices.     

利用Raman散射光谱研究铜铟镓硒薄膜表面的掺杂调节作用

主要研究了采用溅射后硒化方法制备CIGS(铜铟镓硒)薄膜太阳电池的吸收体材料中的表面层掺杂调节问题。并利用Raman散射谱分析研究了样品表面层特征峰的移用,研究结果表明: CIGS薄膜表面层由富In表面层调节为富CuGa表面层后,Raman特征峰位向高波数移动,表明薄膜表面的Ga含量随之变化,并导致表面能带的相应改变,经计算证实了富CuGa表面层样品较之富In表面层样品具有更高的表面能带,从而改善了以此材料为吸收层的太阳电池器件性能, V_oc提高了74 mV,填充因子上升8％,最终使器件转换效率η相应提高了约2％。提高了V_oc与FF。同时表明Raman散射谱作为一种灵敏的表面表征手段,在研究太阳电池吸收层表面状态时十分有力。     

A fast optical profilometer

A simple optical profilometer is described for the measurement of surface profiles. The device is based on the use of a photodiode array that allows a fast examination of the surface and a high sensitivity. It also overcomes the randomness requirements which limit the use of optical devices working on angular diagram or speckle correlation measurements. Preliminary measurements of workpieces profiles are shown.     

Influence of surface scattering on the thermal properties of spatially confined GaN nanofilm

Gallium nitride(GaN), the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In this paper, we investigate the surface scattering effect on the thermal properties of GaN nanofilms. The contribution of surface scattering to phonon transport is involved in solving a Boltzmann transport equation(BTE). The confined phonon properties of GaN nanofilms are calculated based on the elastic model. The theoretical results show that the surface scattering effect can modify the cross-plane phonon thermal conductivity of GaN nanostructures completely, resulting in the significant change of size effect on the conductivity in GaN nanofilm. Compared with the quantum confinement effect, the surface scattering leads to the order-of-magnitude reduction of the cross-plane thermal conductivity in GaN nanofilm. This work could be helpful for controlling the thermal properties of Ga N nanostructures in nanoelectronic devices through surface engineering.     

Influence of different precursor surface layers on Cu(In<Subscript>1-x</Subscript>Ga<Subscript>x</Subscript>)Se<Subscript>2</Subscript> thin film solar cells

The properties of Cu(In_1-xGa_x)Se₂ (CIGS) thin films obtained by selenization of the precursors with different surface layers have been studied, and photovoltaic devices based on the absorbers were measured and analyzed. The devices constructed by the absorbers obtained by selenization of the precursors with CuGa-rich surface layers are improved, compared with those with In-rich surface layers. Through XRD, SEM, SIMS, illuminated J–V, QE and Raman spectra measurements, it was found that the increased Ga contents within the surface region of films and the graded Ga distribution can be realized in the selenized thin films fabricated by the precursors with the CuGa-rich surface layer. Consequently, the performances of the photovoltaic devices based on these thin films are further improved. PACS 61.72.Ss; 87.64.Jt; 68.60.Bs; 81.15.Cd; 84.60.Jt     

On the vertical large eddy breakup device capability to decrease the turbulent drag

The possibility of decreasing the turbulent friction with the use of streamwise-aligned vertical large eddy breakup devices installed normal to the surface of a flat plate in an incompressible equilibrium turbulent boundary layer with a nominally gradientless flow past this plate is studied experimentally. The Reynolds number based on the boundary-layer momentum thickness is 1099 in the cross section where these vertical devices are mounted. It is shown that elements of this geometry are effective tools for modification of the turbulent boundary layer from the viewpoint of both the gain in friction drag and the suppression of turbulent fluctuations of velocity and, hence, can be considered as one of the most important factors of controlling the structure of the near-wall turbulence in the flow past a flat surface.     

Ferrite-ferroelectric layered resonator with electrical and magnetic control

The principle of the design of devices with the double electrical and magnetic control that are based on a ferromagnetic resonator structure coupled with a slotline containing a ferroelectric film is considered. The effective hybridization of the magnetostatic surface wave and the slot mode is demonstrated.     

Molecular beam epitaxy growth of quantum devices

The inherent fragility and surface/interface-sensitivity of quantum devices demand fabrication techniques under very clean environment. Here, I briefly introduces several techniques based on molecular beam epitaxy growth on pre-patterned substrates which enable us to directly prepare in-plane nanostructures and heterostructures in ultrahigh vacuum. The molecular beam epitaxy-based fabrication techniques are especially useful in constructing the high-quality devices and circuits for solid-state quantum computing in a scalable way.     

基于经典光学方法的物体表面微观结构的三维成像

设计了基于经典光学方法的物体表面微观结构的三维成像实验装置以及相应计算程序,从记录不同角度平行光照射下的物体表面照度出发,经图片处理后得到物体表面的三维立体结构.     

Vacuum-deposited, nonpolymeric flexible organic light-emitting devices

We demonstrate mechanically flexible, organic light-emitting devices (OLED's) based on the nonpolymetric thin-film materials tris-(8-hydroxyquinoline) aluminum (Alq(3)) and N, N(?) -diphenyl- N, N(?) -bis(3-methylphenyl)1- 1(?) biphenyl-4, 4(?) diamine (TPD). The single heterostructure is vacuum deposited upon a transparent, lightweight, thin plastic substrate precoated with a transparent, conducting indium tin oxide thin film. The flexible OLED performance is comparable with that of conventional OLED's deposited upon glass substrates and does not deteriorate after repeated bending. The large-area (~1 - cm>(2)) devices can be bent without failure even after a permanent fold occurs if they are on the convex substrate surface or over a bend radius of ~0.5>cm if they are on the concave surface. Such devices are useful for ultralightweight, flexible, and comfortable full-color flat panel displays.     

半导体器件多物理场计算中的热边界条件北大核心CSCD

基于半导体器件的物理模型,联立并求解由电磁场、半导体物理及热力学方程构成的多物理场方程组,实现半导体器件及电路的电磁效应计算。为了更加准确地仿真半导体器件的温度变化,深入研究了多物理场计算中的热边界条件。以肖特基二极管HSMS-282c为例,采用多物理场算法仿真并对比了器件在相同激励(幅值为2V的阶跃脉冲)、不同边界条件下的温度变化情况。实际测量了器件在正向偏置下的表面温度,并于多物理场计算结果进行对比。结果表明,采用热对流边界可以准确仿真半导体器件的热效应。     

Efficient positioning of absorbing material in complex systems by using the Patch Transfer Function method

Given the need to decrease energy consumption in the automobile industry, vehicle weight has become an important issue. Regarding acoustic comfort, the weight of noise reduction devices must be minimized inside vehicle compartments. Consequently, these devices, for example those using poro-elastic materials, must be designed carefully to maximize their influence on noise reduction.The present paper describes a method developed to obtain an efficient positioning of a given surface (or mass) of absorbing material characterized by its surface impedance. This technique is based on the Patch Transfer Function method used to couple complex vibro-acoustic sub-domains and which has been successfully applied in the European ViSPeR and Silence projects.First, a numerical analysis of the possibilities of this method is performed on a non-rectangular cavity with rigid walls after which an experimental validation of this numerical analysis is performed to evaluate the accuracy of the method under real conditions.     

Optimization of sensors based on surface waves in flat-layered structures

A method for increasing the sensitivity of surface-wave sensors in multifilm structures is proposed based on the results of a theoretical study of the reflection of a plane electromagnetic wave from a flat-layered structure containing homogeneous films. A method for optimizing the parameters of the films forming the surface structure is developed and tested. The devices proposed are characterized by high field amplification in a surface layer of multifilm structure and a higher sensitivity to variations in the optical properties of the thin near-surface layer. Application of the proposed multifilm structures is expected to increase significantly the sensitivity of the existing sensors based on surface-plasmon polaritons, which are applied in modern optical multichannel biological, chemical, and physical sensor systems.     

Self-assembled and electrochemically deposited mono/multilayers for molecular electronics applications

For the development of molecular electronics, it is desirable to investigate characteristics of organic molecules with electronic device functionalities. In near future, such molecular devices could be integrated with silicon to prepare hybrid nanoelectronic devices. In this paper, we review work done in our laboratory on study of characteristics of some functional molecules. For these studies molecular mono and multilayers have been deposited on silicon surface by self-assembly and electrochemical deposition techniques. Both commercially available and specially designed and synthesized molecules have been utilized for these investigations. We demonstrate dielectric layers, memory, switching, rectifier and negative differential resistance devices based on molecular mono and multilayers.     

基于金属表面等离子激元控制光束的新进展

表面等离子激元(Surface plasmon polaritons,SPPs)是一种在金属-介质界面上激发并耦合电荷密度起伏的电磁振荡,具有近场增强、表面受限、短波长等特性,在纳米光子学的研究中扮演着重要角色。近年来表面等离子光学和基于SPPs的纳米光子器件的研究引起了国际上科学家们的广泛关注。讨论了SPPs的基本原理和在亚波长结构下的光学特性,介绍了基于亚波长金属结构的表面等离子激元在空间光束准直与聚焦、平面内光束聚焦与传导和在近场纳米光束的控制等方面的研究情况,以及在纳米光子学器件中的潜在应用。     

Transition metal dichalcogenides (TMDCs) heterostructures: Optoelectric properties

Transition metal dichalcogenides (TMDCs) have suitable and adjustable band gaps, high carrier mobility and yield. Layered TMDCs have attracted great attention due to the structure diversity, stable existence in normal temperature environment and the band gap corresponding to wavelength between infrared and visible region. The ultra-thin, flat, almost defect-free surface, excellent mechanical flexibility and chemical stability provide convenient conditions for the construction of different types of TMDCs heterojunctions. The optoelectric properties of heterojunctions based on TMDCs materials are summarized in this review. Special electronic band structures of TMDCs heterojunctions lead to excellent optoelectric properties. The emitter, p-n diodes, photodetectors and photosensitive devices based on TMDCs heterojunction materials show excellent performance. These devices provide a prototype for the design and development of future high-performance optoelectric devices.