一种用于任意功率因数的过零触发器

介绍了一种新型过零触发器,电路简单、性能优越.由于采用了全周波处理和零电流触发方式,使之可以适用于任意功率因数负载;由于采用了晶闸管漏电触发方式,便可以使小小的触发器去触发大容量的晶闸管,而且只有一次隔离便可同时实现同步与触发两大功能,使触发器既不需同步变压器又不需脉冲触发器,实现全电子化.     

超前进位加法器的一种优化设计

描述了超前进位加法器的一种优化设计.在结构上采用按4位分组进行超前进位的方法达到并行、高速的目的.为了在高速运算的同时降低功耗,对求和式子进行了逻辑变换;在晶体管级进行优化的单元电路设计,可减小延时、降低整个电路的面积和功耗.     

氧化铝钝化在晶体硅太阳电池中的应用

首先,回顾了氧化铝钝化技术的发展历程,对制备氧化铝钝化薄膜的手段进行了总结,并且详细描述了氧化铝的材料性质和钝化的机理。其次,指出氧化铝薄膜的优点在于优异的场效应钝化特性和良好的化学钝化性质,因此可以应用于低掺和高掺p型硅表面的钝化。此外,氧化铝薄膜及其叠层还具有良好的热稳定性,符合丝网印刷太阳电池的要求。最后,总结了氧化铝薄膜钝化技术在晶体硅太阳电池中的最新研究动态,指出氧化铝钝化薄膜用于工业生产中存在的问题,并针对这些问题提出了有效的解决方案。     

Environmental effects on the electrical behavior of pentacene thin-film transistors with a poly(methyl methacrylate) gate insulator

The electrical properties of top-contact pentacene thin-film transistors (TFTs) with a poly(methyl methacrylate) (PMMA) gate dielectric were analyzed in air and vacuum environments. Compared to the vacuum case, the pentacene TFT in air exhibited lower drain currents and more pronounced shifts in the threshold voltage upon reversal of the gate voltage sweep direction, together with a decrease in the field-effect mobility. These characteristic variations were explained in terms of two distinctive actions of polar H₂O molecules in pentacene TFT. H₂O molecules were suggested to diffuse under the source and drain contacts and interrupt the charge injection into the pentacene film, whereas those that permeate at the pentacene/PMMA interface retard hole depletion in and around the TFT channel. The diffusion process was much slower than the permeation process. The degraded TFT characteristics in air could be recovered mostly by storing the device under vacuum, which suggests that the air instability of TFTs is due mainly to the physical adsorption of H₂O molecules within the pentacene film.     

Structural and Passivative Behaviors of Cu(In) Thin Film

This investigation prepares a low-resistivity and self-passivated Cu(In) thin film. The dissociation behaviors of dilute Cu-alloy thin films, containing 1.5–5at.%In, were prepared on glass substrates by a cosputter deposition, and were subsequently annealed in the temperature range of 200–600 °C for 10–30 min. Thus, self-passivated Cu thin films in the form In₂O₃/Cu/SiO₂ were obtained by annealing Cu(In) alloy films at an elevated temperature. Structural analysis indicated that only strong copper diffraction peaks were detected from the as-deposited film, and an In₂O₃ phase was formed on the surface of the film by annealing the film at an elevated temperature under oxygen ambient. The formation of In₂O₃/Cu/SiO₂ improved the resistivity, adhesion to SiO₂, and passivative capability of the studied film. A dramatic reduction in the resistivity of the film occurred at 500 °C, and was considered to be associated with preferential indium segregation during annealing, yielding a low resistivity below 2.92 μΩcm. The results of this study can be potentially exploited in the application of thin-film transistor–liquid crystal display gate electrodes and copper metallization in integrated circuits.     

压接型IGBT器件单芯片子模组功率循环试验仿真

压接型绝缘栅双极型晶体管(IGBT)器件因具有双面散热、短路失效和易于串联等优点,正逐步应用到柔性直流输电等领域.但其在工作过程中的热学、力学特性与传统焊接式IGBT模块相比有很大差异,故存在不同的长期可靠性问题.基于有限元法建立了压接型IGBT器件单芯片子模组多物理场耦合仿真模型,研究了三种功率循环仿真条件下器件的热学和力学特性,并且在功率循环过程中利用金属弹塑性模型来模拟材料的瞬态特性.仿真结果表明,IGBT芯片发射极表面与发射极钼片相接触的边缘是应力集中区域,芯片发射极表面栅极缺口和四周边角处有明显的塑性变形.同时,将仿真结果与实际失效的IGBT芯片进行了对比,进一步验证了仿真模型的有效性和适用性.     

双极晶体管g－r噪声模型与深能级分析

本文根据发射结空间电荷区深能级缺陷诱生ｇ－ｒ噪声机构，建立了双极晶体管ｇ－ｒ噪声定量分析模型，从而对实验上观察到的双极晶体管ｇ－ｒ噪声的偏置特性作出了合理的解释．基于该模型，提出了一种利用ｇ－ｒ噪声测量确定双极型器件深能级参数的新方法．     

微纳级双极晶体管的热耗散研究

对于双极性晶体管,由于自身存在的自加热现象,严重地影响着器件的特性。基于热电流方程、泊松方程及电流密度方程,在二维器件仿真环境下,进行了微纳级小尺寸npn双极性晶体管热现象的器件物理特性分析。重点研究了器件的集电极电流IC与晶格温度T的因变关系。研究结果显示,随着IC的增加,器件的晶格温度逐渐升高,VCE保持在3.0V、VBE达到最大值0.735V时,随器件晶格温度的升高VBE将减小。最后,笔者给出了描述晶体管温变关系的三维曲线。     

Gate‐Controlled Energy Barrier at a Graphene/Molecular Semiconductor Junction

The formation of an energy‐barrier at a metal/molecular semiconductor junction is a universal phenomenon which limits the performance of many molecular semiconductor‐based electronic devices, from field‐effect transistors to light‐emitting diodes. In general, a specific metal/molecular semiconductor combination of materials leads to a fixed energy‐barrier. However, in this work, a graphene/C₆₀ vertical field‐effect transistor is presented in which control of the interfacial energy‐barrier is demonstrated, such that the junction switches from a highly rectifying diode at negative gate voltages to a highly conductive nonrectifying behavior at positive gate voltages and at room temperature. From the experimental data, an energy‐barrier modulation of up to 660 meV, a transconductance of up to five orders of magnitude, and a gate‐modulated photocurrent are extracted. The ability to tune the graphene/molecular semiconductor energy‐barrier provides a promising route toward novel, high performance molecular devices.     

沟道应力对GaAs PHEMT材料电性能的影响

设计并用分子束外延(MBE)法制备了不同沟道结构的GaAs PHEMT材料,采用高分辨率X射线双晶衍射仪(DCXRD)、应力测试仪和霍尔测试仪对样品的结晶质量、薄层组分和厚度偏差、应力以及电子迁移率进行了分析表征。探讨了外延片应力与沟道结构的相关性,研究了沟道失配应力对电性能的影响机理。建立了GaAs PHEMT材料热应力引起电子传输特性退化的试验方法,进行了高温和低温存储后材料电性能的演化行为测试,并归纳了热应力引起材料电特性退化的实验结果。结果表明GaAs PHEMT材料经高、低温存储并恢复室温后仍能保持原有电性能,沟道应力对材料电性能的影响主要表现为失配应力。