一种可快速关断的新型横向绝缘栅双极晶体管

提出了一种可快速关断的新型横向绝缘栅双极晶体管(LIGBT)。在LIGBT关断时,利用一个集成的PMOS晶体管来短路发射结,以获得短的关断时间。PMOS晶体管由LIGBT驱动,不需要外部驱动电路。新器件在没有带来任何副作用(如snap-back现象和工艺制造上的困难)的情况下,获得了低的导通压降和快的关断速度。数值仿真结果表明,新器件在不增加导通压降的同时,将关断时间从120ns降到12ns。     

具有沟槽阳极短路的新型沟槽栅场截止绝缘栅双极晶体管

文章提出了一种新型的具有沟槽阳极短路的槽栅场截止型绝缘栅双极晶体管结构。通过引入沟槽短路阳极结构,器件的击穿电压得到了明显提高。仿真结果显示,相比于传统的场截止型绝缘栅双极晶体管,新结构提高了19.5 %的击穿电压,而且新结构具有更小的漏电流。在电流密度为150 A/cm2 时,新结构虽然提高了近百分之九的导通压降,但是关断时间只有传统结构的一半。此外,新结构导通时没有负阻效应。因此,新结构具有更好的关断功耗与导通压降的折中关系。     

一种具有部分高介电常数介质调制效应的IGBT

提出了一种具有高介电常数介质填充沟槽的绝缘栅双极晶体管(IGBT)。分析了高介电常数介质调制效应。结果表明,与普通场阻型IGBT相比,该器件的击穿电压提高了8%,通态压降减小了8%,关断损耗降低了11%;在相同通态压降下,该器件的关断损耗降低了35%。在栅极与原HK介质之间增加介电常数更高的介质,进一步提升了该IGBT的性能。与普通场阻型IGBT相比,在相同击穿电压与通态压降下,改进器件的关断损耗降低了57%。     

一种具有低寿命区的阳极短路4H-SiC IGBT仿真研究

传统沟槽型4H-SiC IGBT中关断损耗较大,导通压降和关断损耗难以折中。针对此问题,文中提出了发射极区域含有低寿命区,同时集电区引入阶梯型集电极的LS-IGBT结构来降低器件的关断损耗。通过同时控制集电区注入的空穴载流子数量和P基区载流子的寿命,在基本维持器件击穿电压的前提下降低器件的关断损耗。使用Silvaco Atlas器件仿真工具对改进结构进行特性仿真分析,并与传统结构进行对比。仿真结果显示,在击穿电压一致的前提下,新结构的关断损耗提升了84.5 %,同时器件的导通压降降低了8.3 %,证明了设计思想的正确性。     

电荷耦合内透明集电极IGBT设计与仿真北大核心CSCD

针对沟槽型绝缘栅双极型晶体管(IGBT)栅电容较大、开关速度较慢的问题,基于内透明集电极(ITC)技术,将电荷耦合(CC)的思想应用于槽栅IGBT中。采用仿真工具MEDICI对电荷耦合内透明集电极IGBT(CC-ITC-IGBT)的击穿特性、导通特性和开关特性等进行了仿真研究,重点研究了电荷耦合区掺杂浓度和局域载流子寿命控制区(LCLC)载流子寿命对器件性能的影响,并和普通的槽栅内透明集电极IGBT进行了对比。结果表明,在给定的参数范围内,新结构在快速关断区域折中特性曲线更好,在低导通压降区域,优势变得不太明显,因而电荷耦合内透明集电极IGBT更适合做快速关断型。     

一种利用高介电常数薄膜改进的快速关断SOI-LIGBT

介绍了一种利用高介电常数薄膜改进的、制作于绝缘衬底上的横向绝缘栅双极型晶体管(SOI-LIGBT)。一方面,覆盖在硅表面的高介电常数薄膜具有引导电通量的作用,可优化器件漂移区的表面电场分布,在器件耐压等级不变的情况下,节约芯片面积,提高导电能力。另一方面,采用高介电常数薄膜有利于减少漂移区中存储的非平衡载流子,可缩短器件的关断时间,降低器件的关断损耗。仿真结果表明,相比于传统500 V等级的SOI-LIGBT,利用高介电常数薄膜改进的新器件可使器件长度缩短15%,导通压降降低10%,关断时间缩短42%,关断损耗减小61%。     

一种新型非穿通型IGBT

本文介绍了一种新型的非穿通型（ＮＰＴ）绝缘栅双极晶体管（ＩＧＢＴ）。该器件直接基于体硅材料上而没有任何降低寿命的步骤。论证了此器件能兼具低通压降、低开关损耗以及高压能力。与常规ＮＰＴ器件相比，其通态压降与关断损耗间的折衷关系更优越。分析了器件的温度特性及擎住特性。结果表明，这种ＮＰＴ结构的温度特性优良，短路电流能力非常高，无擎住发生。     

电流增益与IGBT的开通及关断特性

阐述了关于协调ＩＧＢＴ通态压降和关断时间的最佳关系，在工艺过程中，控制双极晶体管电增益αｐｎｐ最佳值，就可调整通态和关断特性的相互关系。     

一种具有浮空P型埋层的新型FS-IGBT

提出了一种在阳极引入浮空P型埋层的新型场截止绝缘栅晶体管(FS-IGBT)。结合超结与阳极短路的思想,在相同仿真条件下,与传统FS-IGBT相比,新结构的击穿电压提高了13.9%。当通态电流密度为150 A/cm²时,新结构的优化压降增量小于9%,关断时间比传统结构降低了60%以上,并且工作时无负阻现象,实现了导通压降与关断功耗的良好折中。     

一种带有注入增强缓冲层的4H-SiC GTO晶闸管

门极可关断(GTO)晶闸管是应用在脉冲功率领域中的一种重要的功率器件。目前,由于常规SiC GTO晶闸管的阴极注入效率较低,限制了器件性能的提高。提出了一种带有注入增强缓冲层的碳化硅门极可关断(IEB-GTO)晶闸管结构,相比于常规GTO晶闸管结构,该结构有着更高的阴极注入效率,从而减小了器件的导通电阻和功耗。仿真结果表明,当导通电流为1 000 A/cm^2时,IEB-GTO晶闸管的比导通电阻比常规GTO晶闸管下降了约45.5%;在脉冲峰值电流为6 000 A、半周期为1 ms的宽脉冲放电过程中,器件的最大导通压降比常规GTO晶闸管降低了约58.5%。     

一种双发射极沟槽栅超结IGBT

本文对传统沟槽栅超结IGBT进行了改进,得到一种沟槽栅双发射极超结IGBT,本结构第一个发射极区域和传统IGBT结构一样能够发射电子、接收空穴,在p型柱顶部的第二个发射极区域能够起到空穴分流的作用,在有效地提高器件抑制闩锁的能力的同时,保持了超结IGBT器件的高击穿电压(BVoff)和低关断损耗(Eoss)。仿真显示在VGE=10V的条件下,改进结构的闩锁电流从15000A/cm2 提升至 28300A/cm2,器件的击穿电压为810V,在导通压降为1.2V的条件下,关断损耗为6.5 mJ/cm2。     

High‐Performance On‐Chip Thermionic Electron Micro‐Emitter Arrays Based on Super‐Aligned Carbon Nanotube Films

An important advancement towards the realization of miniaturized and fully integrated vacuum electronic devices will be the development of on‐chip integrated electron sources with stable and reproducible performances. Here, the fabrication of high‐performance on‐chip thermionic electron micro‐emitter arrays is demonstrated by exploiting suspended super‐aligned carbon nanotube films as thermionic filaments. For single micro‐emitter, an electron emission current up to ≈20 µA and density as high as ≈1.33 A cm^?2 are obtained at a low‐driven voltage of 3.9 V. The turn‐on/off time of a single micro‐emitter is measured to be less than 1 µs. Particularly, stable (±1.2% emission current fluctuation for 30 min) and reproducible (±0.2% driven voltage variation over 27 cycles) electron emission have been experimentally observed under a low vacuum of ≈5 × 10^?4 Pa. Even under a rough vacuum of ≈10^?1 Pa, an impressive reproducibility (±2% driven voltage variation over 20 cycles) is obtained. Moreover, emission performances of micro‐emitter arrays are found to exhibit good uniformity. The outstanding stability, reproducibility, and uniformity of the thermionic electron micro‐emitter arrays imply their promising applications as on‐chip integrated electron sources.     

Simulated turn-off of 4H-SiC gate turn-off thyristors with gateelectrodes on the p-base or the n-base

Turn-off simulations of a 4H-SiC GTO thyristor structure having a gated p-base and p-type substrate are compared with that having a gated n-base and n-type substrate. Two gate drive circuits are considered, one with a voltage source and resistor between the gate and adjacent emitter region, and the other with a voltage source and resistor between the gate and farthest emitter region. The gated n-base thyristor's substrate current increases atypically before the device turns off. Also, the gated n-base structure turns off when the gate circuit is connected directly to the emitter region furthest from the gate region, but the gated p-base structure does not. Furthermore, turn-off gain is lower for the gated n-base structure due to mobility differences as demonstrated by current-voltage (I-V) and current versus time (I-t) curves     

Global optimization of solar thermophotovoltaic systems

In this paper, we present a theoretical model based on the detailed balance theory of solar thermophotovoltaic systems comprising multijunction photovoltaic cells, a sunlight concentrator and spectrally selective surfaces. The full system has been defined by means of 2n + 8 variables (being n the number of sub‐cells of the multijunction cell). These variables are as follows: the sunlight concentration factor, the absorber cut‐off energy, the emitter‐to‐absorber area ratio, the emitter cut‐off energy, the band‐gap energy(ies) and voltage(s) of the sub‐cells, the reflectivity of the cells' back‐side reflector, the emitter‐to‐cell and cell‐to‐cell view factors and the emitter‐to‐cell area ratio. We have used this model for carrying out a multi‐variable system optimization by means of a multidimensional direct‐search algorithm. This analysis allows to find the set of system variables whose combined effects results in the maximum overall system efficiency. From this analysis, we have seen that multijunction cells are excellent candidates to enhance the system efficiency and the electrical power density. Particularly, multijunction cells report great benefits for systems with a notable presence of optical losses, which are unavoidable in practical systems. Also, we have seen that the use of spectrally selective absorbers, rather than black‐body absorbers, allows to achieve higher system efficiencies for both lower concentration and lower emitter‐to‐absorber area ratio. Finally, we have seen that sun‐to‐electricity conversion efficiencies above 30% and electrical power densities above 50 W/cm² are achievable for this kind of systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Stabilized emission from micro-field emitter for electron microscopy

Micro-fabricated field emitter for the application in miniaturized scanning electron microscope (MSEM) was fabricated on silicon substrate. Field emission studies of the micro-fabricated field emitter were carried out in an ultra high vacuum system. A simple voltage controlled feedback circuit was designed and used to regulate the gate voltage in order to improve the emission current stability of the micro-fabricated field emitter. Preliminary results showed that the emission current fluctuation ((I_max − I_min)/I_ave) was reduced from 80% without feedback current stabilizer to less than 1% with the circuit control.     

Amorphous—Crystalline heterojunction transistors

The characteristics of a new hybrid amorphous-crystalline three-terminal device are described in detail. The device uses a threshold-switching-type chalcogenide glass as the emitter, with a p-type crystalline-silicon base and an n-type silicon collector. When the amorphous emitter is in the off state, the small-signal current gain is significantly smaller than unity. However, once the voltage across the glass is sufficient to produce the on state, the device operates as a transistor with gains well in excess of unity. (Small-signal gains of up to 15 have already been observed in unoptimized configurations.) Under certain conditions, the high-gain on state can be preserved after the switching pulse is removed, suggesting memory-type applications. Previous results on amorphous-crystalline heterojunctions are used to construct a band model for the transistor. This model is used to analyze the steady-state and pulsed-mode characteristics of the device. Recent studies of the on-state current density and carrier concentration are used to calculate the expected gain as a function of current and base doping concentration, with results in good agreement with the experimental data. The behavior of the devices provides another confirmation of the electronic nature of threshold switching in chalcogenide glasses.     

Transient analysis of stored charge in neutral base region

The authors studied the transient relationship between stored charge in the neutral base region and electron current flowing through emitter and collector terminals. Stored charge flows not only through an emitter terminal but also through a collector terminal when emitter-base junction voltage decreases from the switch-on voltage to zero. The ratio of net charge flowing through the emitter terminal to that flowing through the collector terminal is 2:1 once a steady state has been reached. No charge accumulates through the collector terminal when the emitter-base junction voltage increases from zero to the switch-on voltage, however, so the charge partition ratio depends on the sign of the time gradient of the emitter-base voltage     

有射极电阻的基本电路中双极型晶体三极管工作状态的一种判断方法

本文给出含有射极电阻的基本电路中双极型晶体三极管(BJT)工作状态的一种判断方法。对于有射极电阻的基本电路,如果只知道电路中电阻的阻值、BJT的电流放大倍数β和直流电源的电压值,可以先假设其中的BJT处于放大状态,求出BJT在放大状态下的集电极电流IC或基极电流IB,然后与临界饱和状态下的集电极电流ICS或基极电流IBS比较,如果IC相似文献   

Microcontroller‐based simple maximum power point tracking controller for single‐stage solar stand‐alone water pumping system

A simple microcontroller‐based maximum power point tracking controller is proposed for a single‐stage solar stand‐alone water pumping system for remote, isolated, and nonelectrified population, where less maintenance, low cost, and an efficient system is of prime interest. It consists of a photovoltaic (PV) module, a DC–AC converter utilizing space‐vector pulse‐width modulation, an induction motor coupled with a water pump, a voltage sensor, and a current sensor. A space‐vector pulse‐width modulation‐controlled DC–AC converter aided by a fast‐acting on–off supervisory controller with a modified perturb‐and‐observe algorithm performs both the functions of converting PV output voltage to a variable voltage, variable frequency output, as well as extracting the maximum power. A limited variable step size is preferred during transient state, and a steady frequency, which is calculated on the basis of steady‐state oscillation, is set during steady state. A fast‐acting on–off supervisory controller regulates DC link voltage during steady state and enables maximum power point tracking algorithm only during transient state to draw a new voltage reference. In the event of low voltage, the controller switches off the motor but continuously scans for an available PV voltage. The system is not protected against an overcurrent because the maximum current is equal to its short circuit current. The 16‐bit microcontroller dsPIC6010A (Microchip Technology, Inc., Chandler, AZ, USA) is used to implement the control functions. The proposed controller is verified through simulation as well as tested in the laboratory prototype model. The simulation and experimental results show good correlation. Copyright © 2011 John Wiley & Sons, Ltd.