Effects of quantum interference on the electron transport in the semiconductor/benzene/semiconductor junction

Using the tight-binding model and the generalised Green’s function formalism, the effect of quantum interference on the electron transport through the benzene molecule in a semiconductor/benzene/semiconductor junction is numerically investigated. We show how the quantum interference sources, different contact positions and local gate can control the transmission characteristics of the electrode/molecule/electrode junction. We also study the occurrence of antiresonant states in the transmission probability function using a simple graphical scheme for different geometries of the contacts between the benzene molecule and semiconductor (silicon and titanium dioxide) electrodes.     

高功率半导体激光器结温与1/f噪声的关系研究

高功率半导体激光器的结温上升, 不仅影响它的输出功率、斜坡效率、阈值电流和寿命, 而且还会产生光谱展宽和波长偏移. 因此, 热管理成为抽运激光器研发中的一个主要问题. 本文首先建立了噪声功率谱与结温变化的物理模型, 根据压缩感知理论, 将测量得到含有高斯白噪声和1/f噪声的混叠复合噪声信号稀疏化后, 进行基追踪算法去噪, 通过改变算法的迭代次数及测量矩阵大小, 获得1/f噪声电压功率谱与结温变化关系曲线, 避免了直接测量结温的复杂性.通过数值估计结果, 可以较好地指导高功率半导体激光器的热管理工作. 关键词： f噪声')" href="#">1/f噪声 结温度 热阻 高功率半导体激光器     

金属/有机半导体界面偶极层的研究

利用金属/无机半导体界面模型对金属/有机半导体界面偶极层进行了数值研究.讨论了界面处金属/有机半导体原子间距与化学键密度对界面偶极能的影响;分析了界面层电场强度随化学键密度变化的原因;对界面偶极能与金属功函数之间的关系给出了合理的解释.     

The influence of the Dresselhaus spin--orbit coupling on the tunnelling magnetoresistance in ferromagnet/ insulator /semiconductor/ insulator /ferromagnet tunnel junctions

This paper investigates the effect of Dresselhaus spin--orbit coupling on the spin-transport properties of ferromagnet/insulator/semiconductor/insulator/ferromagnet double-barrier structures. The influence of the thickness of the insulator between the ferromagnet and the semiconductor on the polarization is also considered. The obtained results indicate that (i) the polarization can be enhanced by reducing the insulator layers at zero temperature, and (ii) the tunnelling magnetoresistance inversion can be illustrated by the influence of the Dresselhaus spin--orbit coupling effect in the double-barrier structure. Due to the Dresselhaus spin--orbit coupling effect, the tunnelling magnetoresistance inversion occurs when the energy of a localized state in the barrier matches the Fermi energy E_F of the ferromagnetic electrodes.     

Relaxation of femtosecond photoexcited electrons in a polar indirect band-gap semiconductor nanoparticle

A model calculation is given for the energy relaxation of a non-equilibrium distribution of hot electrons (holes) prepared in the conduction (valence) band of a polar indirect band-gap semiconductor, which has been subjected to homogeneous photoexcitation by a femtosecond laser pulse. The model assumes that the pulsed photoexcitation creates two distinct but spatially interpenetrating electron and hole non-equilibrium subsystems that initially relax non-radiatively through the electron (hole)-phonon processes towards the conduction (valence) band minimum (maximum), and finally radiatively through the phonon-assisted electron-hole recombination across the band-gap, which is a relatively slow process. This leads to an accumulation of electrons (holes) at the conduction (valence) band minimum (maximum). The resulting peaking of the carrier density and the entire evolution of the hot electron (hole) distribution has been calculated. The latter may be time resolved by a pump-probe study. The model is particularly applicable to a divided (nanometric) polar indirect band-gap semiconductor with a low carrier concentration and strong electron-phonon coupling, where the usual two-temperature model [1-4] may not be appropriate.     

Metal/semiconductor hybrids consisting of self-assembled CdS nanoparticles on Cd nanowires

We report on the synthesis and the characterisation of metal/semiconductor hybrids consisting of self-assembled CdS nanoparticles on Cd nanowires, which are grown by thermal evaporation of the mixture of CdS and Cr. The growth of the hybrids is attributed to the decomposition of CdS at high temperature and the strain relieving that arises mainly from the lattice mismatch between Cd and CdS. Temperature dependence of zero-field resistance of single nanohybrid indicates that the as-produced Cd/CdS nanohybrid undergoes a metal--semiconductor transition as a natural consequence of hybrid from metallic Cd and semiconducting CdS. The metal/semiconductor hybrid property provides a promising basis for the development of novel nanoelectronic devices.     

An effective pair potential for liquid semiconductor, Se: Structure and related dynamical properties

The effective pair potential of liquid semiconductor Se is extracted from its experimental structure factor data using an accurate liquid state theory and this shows important basic features. A model potential incorporating the basic features of the structure factor extracted potential is suggested. This model potential is then used to describe through low-order perturbation theory, the structure and related dynamical properties like self-diffusion coefficient and shear viscosity of this complex liquid over a wide range of temperatures.     

有机半导体异质界面电荷传输解析模型研究

有机半导体多层薄膜器件的性质很大程度上由有机-有机界面的传输性质所决定，但是现有的关于有机-有机界面的分析模型很难适用于实际器件的模拟.以Miller-Abrahams跳跃传导理论为基础，充分考虑有机-有机界面和金属-有机界面性质的不同，建立了一个新的描述有机-有机异质界面电荷传输的解析模型.结果表明有机异质界面的载流子传输不仅取决于界面的肖特基势垒，而且还取决于界面附近两边的电场强度和载流子浓度.此模型可用于有机半导体多层薄膜器件的电流密度、电场分布和载流子浓度分布的自洽计算. 关键词： 有机半导体 界面 载流子传输     

Nonlinear parametric interactions in ion-implanted semiconductor plasmas having strain-dependent dielectric constants

We report nonlinear parametric interactions using a hydrodynamic model of ion-implanted semiconductor plasmas having strain-dependent dielectric constants(SDDC). High-dielectric-constant materials are technologically important because of their nonlinear properties. We find that the third-order susceptibility varies in the range 10~(-14)~(–10)~(-12)m~2·V~(-2) for ion-implanted semiconductor plasmas, which is in good agreement with previous results. It is found that the presence of SDDC in ion-implanted semiconductor plasma modifies the characteristic properties of the material.     

Spin conductance and spin filtering in ferromagnetic semiconductor quantum point contacts

By combining the spin dependent transport properties of the ferromagnetic semiconductors with the basic physics of the quantum point contacts, we investigate the spin polarized transport through ferromagnetic semiconductor quantum point contacts. We find that the spin conductance strongly depends on the spin orientation, the magnitude of the spin splitting energy and the shape of the cross sections of the point contacts.     

从高质量半导体/超导体纳米线到马约拉纳零能模

作为马约拉纳费米子的"凝聚态版本",马约拉纳零能模是当前凝聚态物理领域的研究热点.马约拉纳零能模满足非阿贝尔统计,可以构建受拓扑保护的量子比特.这种由空间上分离的马约拉纳零能模构建的拓扑量子比特不易受局域噪声的干扰,具有长的退相干时间,在容错量子计算中具有重要的应用前景.半导体/超导体纳米线是研究马约拉纳零能模和拓扑量...     

Morphology and interfacial properties of microrelief metal–semiconductor interface

The effect of the morphology of Au/GaAs interface microrelief, prepared by chemical anisotropic etching, on current flow mechanism, electronic and recombination properties of interface has been investigated. Simulation of I–V curves and optical transmittance of light into semiconductor was made on the basis of the developed theories taking into account the barrier height distribution and the effect of scattering of light by low microrelief.     

All-optical NOT and XOR logic operation at 2.5 Gb／s based on semiconductor optical amplifier loop mirror

All-optical XOR and NOT logic operations based on semiconductor optical amplifier loop mirror (SLALOM) aresimultaneously demonstrated theoretically and experimentally. Based on a segmented semiconductor optical amplifier model, the all-optical logic operation process is simulated theoretically. In an experimental study, 2.5 Gb/s all-optical XOR operation was achieved in the output port of SLALOM, while all-optical NOT operation was achieved in the input port through a circulator at the same time.     

Elementary processes at semiconductor/electrolyte interfaces: perspectives and limits of electron spectroscopy

Semiconductor device properties based on electrolyte contacts or modified by electrochemical reactions are dominated by the electronic structure of the interface. Electron spectroscopy as e.g. photoemission is the most appropriate surface science techniques to investigate elementary processes at semiconductor/electrolyte interfaces. For such investigations a specific experimental set-up (SoLiAS) has been built-up which allows performing model experiments as well as surface analysis after emersion under different experimental conditions. The experimental approach is presented by a number of experiments performed during the last years with GaAs as substrate material. Model experiments by adsorption and coadsorption of electrolyte species give information on fundamental aspects of semiconductor/electrolyte interactions. Emersion experiments give information on a final composition and the related electronic structure of electrodes after electrochemical reactions. The use of frozen electrolytes will help to bridge the gap between these two approaches. With the combination of the experimental procedures one may expect a detailed analysis of electrolyte (modified) interfaces covering chemical composition, electronic structure of surfaces/interfaces as well as surface/interface potentials.     

半导体玻璃微通道板的研制

介绍了半导体玻璃微通道板的主要性能，并与传统铅硅酸盐玻璃的相关性能进行了比较。阐述了半导体玻璃的研制工艺，研究了利用半导体玻璃材料制备微通道板的工艺途径，开发了靠玻璃本身体电导性质而无需氢还原工艺的微通道板，即半导体玻璃微通道板。研制出孔径为20μm、外径为12mm的半导体玻璃微通道板，实验利用紫外光电法测试了微通道板的增益、闪烁噪声和成像性能。结果表明新型微通道板具有明显的电子增益和低的闪烁噪声，并且通道表面稳定；利用磷硅酸盐玻璃材料可以实现体导电微通道板的制备。     

Spin-dependent collection in ferromagnet/semiconductor contacts

In ferromagnet/semiconductor contacts, the different timescales of the phenomena driving the spin transport in the semiconductor induce a strong reduction of the possible spin filtering effect. We propose an original structure with double contacts to overcome this difficulty. Using Monte Carlo simulation, we show that the spin asymmetry of the current collected in such a structure may be significantly higher than in a single contact.     

铁磁/半导体(绝缘体)/铁磁异质结中渡越时间与两铁磁层磁矩夹角变化的关系

在群速度概念的基础上, 研究了自旋极化电子隧穿通过铁磁体/半导体(绝缘体)/铁磁体异质结时, 渡越时间随两端铁磁层中磁矩夹角变化的关系. 研究结果表明: 当中间层为半导体层时, 由于半导体层中的Rashba自旋轨道耦合强度的影响, 自旋向上电子和自旋向下电子的渡越时间差会在两铁磁层相对磁矩夹角为π/2和3π/2附近出现一个极小值. 当中间层为绝缘体层时, 势垒高度的变化会导致不同取向的自旋极化电子渡越时间差的变化, 并当势垒高度超过一临界值时发生翻转. 关键词： 铁磁体/半导体(绝缘体)/铁磁体异质结 Rashba自旋轨道耦合强度 渡越时间 磁矩     

Propagation and collision of soliton rings in quantum semiconductor plasmas

The intrinsic localization of electrostatic wave energies in quantum semiconductor plasmas can be described by solitary pulses. The collision properties of these pulses are investigated. In the present study, the fundamental model includes the quantum term, degenerate pressure of the plasma species, and the electron/hole exchange–correlation effects. In cylindrical geometry, using the extended Poincaré–Lighthill–Kuo (PLK) method, the Korteweg–de Vries (KdV) equations and the analytical phase shifts after the collision of two soliton rings are derived. Typical values for GaSb and GaN semiconductors are used to estimate the basic features of soliton rings. It is found that the pulses of GaSb semiconductor carry more energies than the pulses of GaN semiconductor. In addition, the degenerate pressure terms of electrons and holes have strong impact on the phase shift. The present theory may be useful to analyze the collision of localized coherent electrostatic waves in quantum semiconductor plasmas.     

Quantum point contact conductance in ferromagnetic semiconductor/superconductor junctions

An extended Blonder-Tinkham-Klapwijk approach is applied to study how the tunneling conductance in ferromagnetic semiconductor/s-wave superconductor (FS/SC) junction, where the FS region is a quantum wire, is manipulated by the mismatches of the effective mass between the FS and SC, spin polarization in the FS, as well as the strength of potential scattering at the interface. It is demonstrated that in the single-mode case they have different influences on the tunneling spectra.     

对半导体pn结接触电势的一个讨论

讨论了半导体pn结内建电场和接触电势的形成与可测性，回答了在半导体物理学pn结内容教学中学生经常会提出的一个似是而非的问题．从热力学第一定律、金属-半导体接触等不同角度详细解释了热平衡(零偏下)时pn结不可能对外输出电压和电流的原因．