Studies on the high-frequency properties of 〈111〉, 〈110〉 and 〈100〉 oriented GaAs IMPATT diodes

High-frequency analysis has been carried out to predict the rf performance of 111, 110 and 100 oriented p ⁺ nn ⁺, n ⁺ pp ⁺ (single drift region) and n ⁺ npp ⁺ (double drift region) GaAs IMPATT diodes for opertion at 35 and 60 GHz. The microwave performance is observed to be highly sensitive to crystal orientation in case of p ⁺ nn ⁺ and n ⁺ npp ⁺ diodes whereas orientation of the substrate has negligible effect on n ⁺ pp ⁺ avalanche diodes. The calculation shows that 111 oriented GaAs IMPATT diode would provide the largest magnitude of negative resistance and negative conductance for both SDR p ⁺ nn ⁺ and DDR n ⁺ npp ⁺ diodes which indicates that high microwave power with high conversion efficiency can be realised from these 111 oriented GaAs devices. This result can be explained from the experimental data of electron and hole ionization rates for different orientations in GaAs.     

C42〈Al〉C32〈Si〉等混合物吸收光谱特性

用电弧放电＾［１］、Ｈｅ气对流的方法制备出了含Ｃ４２〈Ａｌ〉、Ｃ３２〈Ｓｉ〉、Ｃ２８〈Ｆｅ〉和Ｃ３０〈Ｃａ〉的混合物。对该混合物作了吸收光谱测量，并与Ｃ６０等全碳分子的吸收光谱作了比较，结果表明，Ａｌ、Ｓｉ、Ｃａ和Ｆｅ原子嵌入Ｃ４２等全碳分子后，并没改变吸收峰位，而只是改变了分子的π→π＾＊跃迁和ｎ→π＾＊跃迁几率。     

关于〈运动学〉的几点说明

介绍作者编写《运动学》教材时的一些考虑。说明如何应用大学物理观点分析高中物理质点运动的速度、加速度概念及运动独立性问题。     

The influence of elastic stress fields on ionic transport through a 〈superionic crystal〉-〈electrode〉 heterojunction

The appearance of a current in an external circuit has been observed upon elastic deformation of a local region of the superionic crystal RbAg₄I₅. The dependence of the magnitude and sign of the deformation current on the region of application of the local load on the sample is examined, and the temporal characteristics of the processes are investigated. The influence of an elastic deformation on processes taking place at the 〈superionic crystal〉-〈electrode〉 heterojunction is investigated, and a mechanism of generation of the deformation current is proposed. The generation of photostimulated currents upon illumination of a local region of the superionic conductor by light corresponding to intracenter excitation of optically active centers is considered. It is shown that the elastic stress fields arising around photoexcited centers are responsible for the generation of photostimulated currents. Fiz. Tverd. Tela (St. Petersburg) 41, 1766–1771 (October 1999)     

《范仲淹〈渔家傲〉新解——回应周教授〈学界领袖哪里去了?〉》发表后记

<正>《范仲淹〈渔家傲〉新解——回应周教授〈学界领袖哪里去了?〉》(《物理》(北京)2014年第43卷(6期)第417页)这篇文章发表之后,几位读者对于我在"后记"中写的这一句话"我们可以据此反省思索,如何在21世纪的中国,再培养出一批(而不止一位)学界领袖。"有所疑     

高等职业教育法研究：〈模拟电子技术〉示范课

本文从高等职业教育的特点入手，重点探讨高职教育的数学方法。主要从教学大纲、教材选配、教学组织、初中阵个方面进行研究和探索。     

单轴〈111〉应力硅价带结构计算

基于k·p微扰法计算了单轴〈111〉应力作用下硅的价带结构, 并与未受应力时体硅的价带结构进行了比较. 给出了单轴〈111〉应力作用下硅价带顶处能级的移动、分裂以及空穴有效质量的变化情况. 计算所得未受应力作用时硅价带顶处重空穴带、轻空穴带有效质量与相关文献报道体硅有效质量结果一致. 拓展了单轴应力硅器件导电沟道应力与晶向的选择范围,给出的硅价带顶处重空穴带、轻空穴带能级间的分裂值和有效质量随应力的变化关系可为单轴〈111〉应力硅其他物理参数的计算提供参考. 关键词： 单轴应力硅 k·p法')" href="#">k·p法 价带结构     

Quantitative characterization of AlAs/GaAs interfaces by high-resolution transmission electron microscopy along the 〈100〉 and the 〈110〉 projection

The interface microstructure of AlAs/GaAs quantum wells grown by molecular beam epitaxy (MBE) was investigated by transmission electron microscopy (TEM). High-resolution transmission electron microscopy (HRTEM) yields information about the width of the chemical transition between the binary components and about the lateral step distances along the interface. The chemical composition is quantitatively determined by the application of a pattern recognition procedure based on the Fourier transformation of image unit cells. Along the 100 zone axis the composition across the interfaces is obtained with a precision of ±10 atomic percent and with a spatial resolution of 0.28 nm. Despite a lower chemical sensitivity a quantitative chemical analysis was also carried out for images along the 110 projection.     

工科〈大学物理〉教学与高素质人才的培养

本文介绍了作者在工科＜大学物理＞教学中培养高素质人才的体会与实践。     

工科〈大学物理〉教学与高素质人才的培养

本文介绍了作者在工科〈大学物理〉教学中培养高素质人才的体会与实践．     

极端相对论性高能核碰撞的〈pr〉分布

本文以蒙特卡罗方法计算SU(3)群格点规范得到的能密函数作为状态方程,用流体力学模型定量研究了极端相对论性高能核碰撞产生的终态粒子平均横动量的分布,并与JACEE实验组的数据比较,发现在初态能量密度较大的区域里看到异常剧增现象不是由夸克胶子等离子体的流体运动所引起。文中给出了不同初始热平衡时间和初始半径下的分布对比数据,发现分布的基本特征不因初始参数的变化而改变。     

Properties of the Schottky Barriers on compensated PbTe〈Ga〉

C-V, I-V and photoelectric characteristics were investigated for some metals with different work functions, deposited onto compensated PbTe〈Ga〉 substrates with low carrier concentrations N, P ⩽ 10¹⁶cm⁻³. The surfaces of the PbTe〈Ga〉 substrates were prepared by anode-mechanical polishing, that results in enriching of the surface by Te. It was shown that the heights of the potential barriers Ø_B of the Schottky contacts prepared by oxidization in air anode-mechanically polished PbTe surfaces do not depend on the metal work function of Cu, Ag, Au and In. The highest values of resistance-area product were obtained for the Cu/p-PbTe〈Ga〉 contacts (R₀A≅ 1 × 10⁴Ωcm²) and were slightly lower than the R₀A value limited by the thermoemission current.     

〈数字电子技术〉课程在高职教育中的教学特色

本文是针对目前高等教育的发展现况以及发展趋势，对具体课程教学特色的研究。针对《数字电子技术》课程在教学计划、理论教学实践教学等方面的教学特色进行深入探讨，提出具体教学计划、教学方法、教学手段及制作教具等。     

非晶态超导体的声子谱参数λ,〈ω〉和〈ω~2〉与霍耳系数之间的经验关系

在大量的非过渡金属和合金中,非晶态超导体的声子谱参数λ,<ω>和<ω~2>与霍耳系数R_H之间存在着一个经验关系:在R_H=-3.5—-4.0×10~(-11)m~3/As之间存在着λ,<ω>和<ω~2>的最大值。上述声子谱参数与相应的液态金属的霍耳系数R_(HL)之间也存在着一个和上述类似的经验关系。最后讨论了非晶态超导体的转变温度T_c的提高问题。     

格点Schwinger模型中〈φφ〉的变分计算

本文利用格点规范理论的变分方法,计算Schwinger模型中Naive格点费米子的真空凝聚参数〈φφ〉,得到较好的标度行为。