磁约束脉冲放电电路分析

在已进行的实验研究的基础上,对所设计的磁约束脉冲放电电路进行了理论分析,获得了有关磁约束放电情况下的电路特性的认识。作者的研究为应用于磁约束放电的电路的进一步研究和改进打下了基础。     

一种多晶硅高温压力传感器

制作压力传感器时，在二氧化硅层上淀积多晶硅膜，既可利用优良的机械特性，又可保证压敏电阻与衬底间具有良好的绝缘性，由此可大大提高器件的温度特性。介绍了一种多晶硅压力传感器的原理和设计。实验结果表明，这类传感器具有灵敏度好，精度高等特点，电路工作范围为０－２５０℃，且具有良好的温度稳定性。     

空间调制器——实时光处理

空间光调制器（SLM）对我们还是一个比较陌生的名词，但它却正悄悄并稳步地进入我们的日常生活。空间光调制器又称光问，实质上是个随时间变化的挡板。光学十字开关便是它众多功能中的一例。它可看作由一组线性发光体列阵组成的栅，而由一组线性光探测器列阵组成另一个栅，两者互相垂直并隔一小段距离。每个发光体都能照到所有的探测器上。如上所述，这样一种光学十字开关似乎并不引起人们的兴趣。但如在发光体列阵与探测器列阵之间插入一挡板，只有板上能透光的部分可以将特定的发光体与选定的探测器连接。这个挡板就是空间光调制器。这…     

Electrical characteristics of high performance Au/n-GaN schottky diodes

Au/n-GaN Schottky diodes with the Au electrode deposited at low temperature (LT=77K) have been studied. In comparison, the same chip of GaN epitaxial layer was also used for room temperature Schottky diodes. The low temperature Schottky diodes exhibit excellent performance. Leakage current density as low as 2.55×10⁻¹¹ A·cm⁻² at −2.5 V was obtained in the LT Schottky diodes. The linear region in the current-voltage curve at forward bias extends more than eight orders in current magnitude. Current-voltage-temperature measurements were carried out to study the characteristics of the LT Schottky diodes. A typical barrier height of about 1.32 eV for the LT diode, which is the highest value ever reported, was obtained. The obvious enhancement in electrical performance makes the LT processing a very promising technique for GaN device application although the detailed mechanisms for the LT Au/n-GaN Schottky diodes are still under investigation.     

电子在一维方势垒顶部的透射

文中对入射电子能量等于一维方势垒高度时，电子对势垒的透射情况进行了理论分析，导出了这一条件下的电子透射系数与势垒高度及势垒宽度之间的关系，并证明了电子对一维方势垒的透射系数Ｔ是入射电子能量Ｅ的连续函数。     

Schottky barriers on n-GaN grown on SiC

Characteristics of Schottky barriers fabricated on n-type GaN were investigated. The barriers were formed by vacuum thermal evaporation of Cr, Au, and Ni. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the barriers were measured in a wide temperature and current density range. Fundamental parameters (barrier height and built-in potential) of the Schottky barriers were determined. The dependence of the barrier ideality factor on doping concentration in GaN was measured. Correlation between the barrier height and metal work function was observed. The electron affinity for GaN was determined using both C-V and I-V characteristics. The current flow mechanism through the barriers is discussed.     

Epitaxial TiN based contacts for silicon devices

We have grown high quality epitaxial TiN/Si(100) and Cu/TiN/Si(100) heterostructures by pulsed laser deposition. The epitaxial TiN films have the same low (15 μΩ-cm) resistivity as TiSi₂ (C-54) phase with excellent diffusion barrier properties. In addition, Schottky barrier height of TiN was close to that of TiSi₂ (0.6-0.7 eV). Auger and Raman spectroscopy revealed that the films were stoichiometric TiN and free from oxygen impurities. The x-ray diffraction and transmission electron microscope (TEM) results showed that the TiN films deposited at 600°C were single crystal in nature with epitaxial relationship TiN|| Si. The Rutherford baskscattering channeling yield for TiN films was found to be in the range of 10–13%. The epitaxy of Cu on TiN was found to be cube-on-cube, i.e., Cull<100>TiN||Si. The Cu/TiN and TiN/Si interfaces were found to be quite sharp without any indication of interfacial reaction. The growth mechanism of copper on TiN was found to be three-dimensional. We discuss domain matching epitaxy as a mechanism of growth in these large lattice mismatch systems, where three lattice constants of Si(5.43?) match with four of TiN(4.24?) and seven units of Cu(3.62?) match with six of the TiN. Thus, for next generation of device complementary metal oxide semiconductor structures, Cu/TiN/Si(100) contacts hold considerable promise, particularly since Cu is a low resistivity metal (1.6 μΩ-cm) and is considerably more resistant to electromigration than Al. The implications of these results in the fabrication of advanced microelectronic devices are discussed.     

急倾斜工作面防水煤柱留设方法及其稳定性分析

采用相似模拟实验及地质雷达探测相结合的方法,研究了四川省煤炭产业集团有限责任公司铁山南煤矿急倾斜采煤工作面采动断裂带的分布范围.结果表明,上下采空区采动裂隙没有贯通.应用3D-σ有限元程序,计算了防水煤柱宽度分别为60,70,75和80 m时各特征点的应力大小,在此基础上分析了防水煤柱的稳定性.计算结果表明,当防水煤柱宽度为75 m时,各特征点的强度大于应力,但稳定性系数较小;当防水煤柱宽度为80 m时,其稳定性系数为1.2～1.9.根据试验及模拟结果并结合工程实际,确定防水煤柱宽度为80 m.应用综合方法确定的防水煤柱宽度比经验方法减少30 m.     

Experimental evaluation of insulation material in roofing system under tropical climate

The objective of this study is to determine the influence of radiant barriers on conductive and radiative heat transfers when they are integrated to a building envelope and to compare their efficiency to traditional insulation material (mineral wools, polystyrene). It is also about determining which insulation material and process can lead to a better heat flux reduction through a building roof. For this study four identical small-scale test cells were used. Their respective roof was equipped with the insulation material to be tested: One with polystyrene, the second with a radiant barrier the third one with fibber glass and the last one with no insulation material was considered as the reference cell. Different test were performed with a view to evaluate the influence of parameters such as roof absorptivity and roof air layer ventilation on the heat flux reduction through the roof. With the measured temperature, the conductive and radiative heat fluxes were calculated. With a white corrugated iron roof top the heat flux reduction provided by the radiant barrier is 37%. With a black one this material allows a reduction of 33%. It is shown that whatever the roof absorptivity value, the radiative heat flux is predominant over the conductive one. With no ventilation, the radiant barrier is comparable to polystyrene and fiber glass; when the airspace is ventilated the radiant barrier provides a better insulation.     

A screen-printed interdigitated back contact cell using a boron-source diffusion barrier

A low-cost approach to fabricating interdigitated back contact cells is carried out on the principle of screen-printing a material that serves both to dope the rear surface and as a diffusion barrier to the dopant species of the opposite polarity. With this technique, an interdigitated pattern of n⁺ and p⁺ regions is formed on the cell back. Shunt-free rear interdigitated junctions are achieved. This work produced a cell with confirmed conversion efficiency of 10.5%. Areas for further efficiency gains are discussed.