利用固体物理LED发光原理测量普朗克常数

普朗克常数是物理学中一个重要的常数,利用二极管的量子特性探讨运用发光二极管来测量普朗克常数。通过测量二极管的伏安曲线,确定其阈值电压,根据相关量子理论,间接得出普朗克常数,通过与光电效应法测量普朗克常数的测量结果相比较,结果表明此误差略大,但作为一种新型的实验方法探索,对于开拓学生的综合素养还是非常有益的。     

Laser surface alloying of an electroless Ni–P coating with Al-356 substrate

Laser surface alloying of an electroless plating Ni–P coatings on an Al-356 aluminium alloy was carried out using a 1-kW pulsed Nd:YAG laser. The microstructure, chemical composition and phase identification of the alloyed layer were determined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD), respectively. It was shown that laser surface treatment produced a relatively smooth, crack-free and hard surface layer. The hardness of the surface significantly increased due to the formation of the uniformly distributed fine Ni–Al intermetallic phases. The corrosion behaviour of the surface alloyed specimens in 3.5% NaCl solution at 23 °C was also determined by electrochemical techniques. The laser-alloyed surface showed an improved corrosion and pitting potential compared to the substrate as well as the plated Ni–P coating.     

Weyl’s Type Estimates on the Eigenvalues of Critical Schrödinger Operators

We consider on a bounded domain \(\Omega \subset {\mathbb{R}}^N\) , the Schrödinger operator ? Δ ? V supplemented with Dirichlet boundary solutions. The potential V is either the critical inverse square potential V(x) = (N ? 2)²/4|x|^?2 or the critical borderline potential V(x) =  (1/4)dist(x, ?Ω)^?2. We present explicit asymptotic estimates on the eigenvalues of the critical Schrödinger operator in each case, based on recent results on improved Hardy–Sobolev type inequalities.     

具有P?schl-Teller型标量势与矢量势的Klein-Gordon方程和Dirac方程的束缚态

给出了具P?schl-Teller型标量势与矢量势的Klein-Gordon方程和Dirac方程的s波束缚态解. 关键词： P?schl-Teller势 Klein-Gordon方程 Dirac方程 束缚态     

具有P型覆盖层新型超级结横向双扩散功率器件

为了设计功率集成电路所需要的低功耗横向双扩散金属氧化物半导体器件(lateral double-diffused MOSFET), 在已有的N型缓冲层超级结LDMOS(N-buffered-SJ-LDMOS)结构基础上, 提出了一种具有P型覆盖层新型超级结LDMOS结构(P-covered-SJ-LDMOS). 这种结构不但能够消除传统的N沟道SJ-LDMOS由于P型衬底产生的衬底辅助耗尽问题, 使得超级结层的N区和P区的电荷完全补偿, 而且还能利用覆盖层的电荷补偿作用, 提高N型缓冲层浓度, 从而降低了器件的比导通电阻. 利用三维仿真软件ISE分析表明, 在漂移区长度均为10 μm的情况下, P-covered-SJ-LDMOS的比导通电阻较一般SJ-LDMOS结构降低了59%左右, 较文献提出的N型缓冲层 SJ-LDMOS(N-buffered-SJ-LDMOS)结构降低了43%左右.     

The reusability characteristics of LiF:Mg,Cu,P with a maximum intensity at 280 °C in an environment with elevated temperature

Efforts are aimed at finding a method that could serve TL dosimetric measurements in the range of low-dose but carried out in an environment with elevated temperature. The temperature at the position of the maximum intensity of LiF:Mg,Cu,P was about 280 °C when annealed at 460 °C. LiF:Mg,Cu,P with a maximum intensity at 280 °C should present good thermal stability. The TL intensity of LiF:Mg,Cu,P with a maximum intensity at 280 °C was about 54% of the standard LiF:Mg,Cu,P, it should have a minimum measurable dose in the range of micro-Gy. LiF:Mg,Cu,P with a maximum intensity at 280 °C could be re-used by the 660 °C/30 min annealing, followed by 270 °C/20 min, 240 °C/10 min and 460 °C/30 min. It's possible for LiF:Mg,Cu,P to be extended application for low dose test in an environment with elevated temperature.     

Characteristics of xenon-lamp pumped pyrromethene 567-doped dye laser based on polymethylmethacrylater

The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation. The experimental setup is an ordinary industrial product without special design. The bulk transmission losses, the output energy, and the other lasing properties are compared. The medium with the lowest transmission loss, measured to be 0.392 %/cm at 633 nm, gives a laser output of 130 mJ with a slope efficiency of 0.082%.     

旋涂速度对制备P3HT有机场效应晶体管性能的影响

采用溶液化的方法制备了以PMMA为绝缘层、P3HT为有源层的有机场效应晶体管.研究了P3HT有源层和PMMA绝缘层的旋涂速度对器件性能的影响.实验结果表明,当P3HT和PMMA的旋涂速度均为2 000 r/min时,器件的性能最佳.峰值场效应迁移率为6.84×10^-2 cm²·V^－1·s^－1.结果表明,选择适当的旋涂速度是一种有效提高溶液化制备有机场效应晶体管性能的方法.     

Structural, optical and electronic properties of P doped p-type ZnO thin film

P doped ZnO films were grown on quartz by radio frequency-magnetron sputtering method using a ZnO target mixed with 1.5 at% P₂O₅ in the atmosphere of Ar and O₂ mixing gas. The as-grown P doped ZnO film showed n-type conductivity, which was converted to p-type after 800 °C annealing in Ar gas. The P doped ZnO has a resistivity of 20.5 Ω cm (p∼2.0×10¹⁷ cm⁻³) and a Hall mobility of 2.1 cm² V⁻¹ s⁻¹. XRD measurement indicated that both the as-grown and the annealed P doped ZnO films had a preferred (0 0 2) orientation. XPS study agreed with the model that the P_Zn-2V_Zn acceptor complex was responsible for the p-type conductivity as found in the annealed P-doped ZnO. Temperature-dependent photoluminescence (PL) spectrum showed that the dominant band is located at 3.312 eV, which was attributed to the free electronic radiative transition to neutral acceptor level (FA) in ZnO. The P_Zn-2V_Zn acceptor complex level was estimated to be at E_V=122 meV.     

基于单目图像和方向的测距系统及性能分析

 针对非合作大目标的被动测距问题,介绍了一种基于单目图像序列和成像方向的测距系统,并进行了性能分析.这种测距系统的特点是无需初始距离导引,它对目标距离的估计借助于专门的定位方程,方程由目标特征线度、摄像机的空间坐标、目标在采样时刻对相机的方位角和俯仰角决定.其中,方位角和俯仰角通过光电经纬仪获得,摄像机的空间坐标通过GPS获得,目标特征线度通过相邻帧图像匹配得到.分析表明,该系统的性能主要取决于特征线度的准确度,其他测量误差如目标的方位角、俯仰角和摄像机的空间坐标对其影响较小.目标特征线度选取时,在相邻帧目标图像匹配点中,筛选出三个具有较大极限的尺度不变特征变换关键点,构造三角形及其外接圆,在外接圆上取经过三角形重心且平行或垂直于尺度不变特征变换主方向的弦线作为特征线度,这种特征线度对目标旋转不敏感.实验结果表明这种测距方法能够实现对非合作大目标的被动测距.