新型可关断晶闸管的研制现状与动向

新型可关断晶闸管的研制现状与动向晶闸管是最适合在大电流下应用的电力半导体器件，其电流增益大，导通电阻小，现已有快速、逆导、不对称、双向、光控等多种类型产品，制造和应用技术日趋成熟，目前性能最高水平为６．５ｋＶ／３．５ｋＡ。普通晶闸管的不足之处是门极不...     

双向晶闸管原理及在交流调压电路中的应用

双向晶闸管与单向晶闸管一样,都具有触发控制特性。它的触发控制特性与单向晶闸管有很大的不同,只要在它的控制极上加上正的或负的触发脉冲,都能使管子触发导通,调节触发脉冲,改变了双向晶闸管的导通角,相应地改变了负载上的交流电压,实现了交流调压。     

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%。     

Bi-mode逆导门极换流晶闸管结构与特性研究

Bi-mode逆导门极换流晶闸管(BGCT)是为了改善传统逆导门极换流晶闸管(RC-GCT)电流均匀性和提高硅片有效面积利用率而提出的一种新结构。通过分析BGCT器件的版图布局结构,采用Sentaurus TCAD软件模拟并分析了BGCT、传统结构RC-GCT和IGCT传统功率器件的通态特性、正向阻断特性和关断特性,着重比较了RC-GCT与BGCT在400K温度下不同工作模式下特性差异。分析研究结果表明,BGCT器件能够改善RC-GCT器件的通态特性,提高硅片面积的利用率。     

由紧凑型高dI／dt门极驱动单元驱动的新型对称门极换流晶闸管

在工业大功率应用领域已经推出了多种类型（对称，非对称以及逆向导通）的门极换流晶闸管（GCT）器件，为了用它来实现更高性能、更加合适的系统，人们期望对门极换流晶闸管展开进一步的研究，本文提出了对称门极换流晶闸管的一种新方案。     

一种具有n型隐埋载流子存储层的BRT新结构

提出了一种具有n型隐埋载流子存储层的基极电阻控制晶闸管（BRT）新结构。利用TCAD仿真软件对其工作机理和静态特性进行了分析，并与双栅BRT进行了性能对比。结果表明，新器件导通时会产生电子注入增强效应，由绝缘栅双极晶体管模式快速转换成晶闸管模式，当n型隐埋层浓度为8×1015 cm-3，隐埋层与p基区相接并与p++分流区距离接近时，能够有效抑制器件中的电压折回现象，获得良好的导通特性。新器件的导通压降为3.84 V，比传统器件减少了26%。     

30 V UMOS中影响导通电阻平坦度的因素分析

功率MOSFET作为开关器件时,导通电阻的平坦度是衡量其性能的重要参数。研究影响导通电阻平坦度的因素,并对其进行优化,有助于改善器件的性能。低压UMOS中,沟道电阻是导通电阻的主要部分。文章以沟道电阻为分析对象,利用公式分析影响因素,通过Sentaurus TCAD仿真验证了导通电阻平坦度的变化趋势。通过改变P型基区离子注入剂量和栅氧层厚度进行仿真。仿真结果表明,通过减小栅氧层厚度和减少P型基区注入剂量,可获得较好的导通电阻平坦度。     

一种改进的晶闸管触发电路研究

晶闸管触发电路的作用是产生符合要求的门极触发脉冲,保证晶闸管在需要的时刻由阻断变为导通。为了在寒冷条件下对软起动器的晶闸管可靠触发,针对传统触发电路触发脉冲前端无强脉冲,在传统的触发电路基础上进行了改进。通过改进,使触发脉冲的电流前沿有了强触发脉冲。实验证明,该触发电路满足了实际的需要。     

新型高速功率开关器件—800V10A静电感应晶闸管的研制

本文论述了新型高速功率开关器件—800V、10A静电感应晶闸管的结构、设计和工艺研究。说明了所研制的器件的直流特性和开关特性,得到导通时间1.8μs,关断时间1.5μs的较好效果。     

基于AT89C52单片机的晶闸管触发器的设计

设计了一款基于AT89C52单片机控制的三相全控桥式晶闸管的触发器。AT89C52采集同步信号,接收外部输入的导通角,依靠软件定时,进而输出延时角的脉冲信号,经放大后,送入晶闸管控制极。实验针对触发装置工作不稳定、精度不高,提出了解决方案。     

Evaluation of turn-on performance of P-i-N rectifiers and IGBT'sunder zero voltage switching

This paper compares the turn-on performance of two vertical power bipolar devices, viz, P-I-N diode and IGBT, under Zero Voltage Switching (ZVS). Although both the devices are “conductivity modulated” during turn-on, the IGBT carrier dynamics distinctly differ from that of a P-i-N rectifier. It is shown that, for identical drift region parameters, the conductivity modulation in the IGBT is significantly lower compared to that in a P-i-N rectifier mainly because of carrier flow constraints in the IGBT and the inherent bipolar transistor-like carrier distribution in the IGBT. 2-D mixed device and circuit simulations were performed to understand the behavior of the two devices during turn-on under ZVS. The mixed device and circuit simulator was also used to study the effects of variations in the rate of change of current (di/dt) through the device during turn-on, carrier lifetime and temperature on the turn-on behavior of the two bipolar devices under ZVS     

The current pulse ratings of thyristors

This paper describes how the current pulse ratings of thyristors during turn-on spreading can be obtained from the maximum allowable junction temperature based on time-to-failure using a combination of analytical and experimental methods. The instantaneous junction temperature rise of a thyristor is analyzed with the aid of a digital computer. In the calculation of temperature rise, the transient thermal impedance during turn-on spreading is considered. Analyzed results agree with the values obtained directly by an infrared detector. In order to estimate the maximum allowable junction temperature based on time-to-failure, "step-stress capability tests" were conducted. In many cases, it was found that there were modes of both catastrophic and degradation failure. The maximum allowable junction temperature was estimated for the nonrepetitive and repetitive current pulse ratings.     

Probed determination of turn-on spread of large area thyristors

Thyristors (SCR's) were specially constructed to permit the direct observation of the lateral spread of turn-on within the device. The effects on the spread of turn-on of the load current, basewidths, temperature, anode-cathode voltage, gate control pulse, and a large inhomogeneity were observed. The spreading velocity of the on-state and the load current are related approximately by the expressionV^{n} propto Iat high load currents. The spreading velocity is higher in devices with narrower basewidths and increases with temperature. Neither the anode-cathode voltage before turn-on nor the gate control pulse affect the spreading velocity of the on-state. Measurements on end gate devices and center gate linear devices show that triggering at the center enables an equivalent area of the SCR to turn on in less time than occurs when triggering at the end. A large gap in the emitter layer will delay the spread of the on-state but will not necessarily stop the spreading.     

Embedding a feedforward controller into the IGBT gate driver for turn-on transient improvement

This paper proposes an active gate drive method based on a feedforward control for turn-on condition in IGBTs. The transient improvement with minimum undesirable effect on the efficiency is the main objective of this research. The new gate driver (GD) improves the trade-off between switching loss and device stress at the turn-on condition, without getting feedback from the output. The operation principle and implementation of the controller in the GD are presented. The effect of the proposed GD on the transient behaviour, efficiency, junction temperature and electromagnetic interference (EMI) during turn-on switching is evaluated by both simulation and experimental tests. The new GD is evaluated under hard switching condition and various frequencies. Advantages and disadvantages of the method have been discussed.     

Characteristics of AlGaAs/GaAs heterostructure RT-SCR model

Electrical properties of a resonant-tunneling-semiconductor-controlled rectifier (RT-SCR) model have been presented. The current, temperature, gain, doping concentration, and layer size versus voltage relationships have been numerically obtained. The RT-SCR device requires smaller turn-on voltage than a comparable traditional device for the same gate current. This indicates that, in comparison with the traditional thyristor, a smaller control current may be used to turn on the device at a particular voltage. Characteristics of the device are affected by p1, n1, and p2 regions. It is showed that higher doping concentrations cause lower turn-on voltages and an increase in the region width results in higher turn-on voltages for p1 and p2 regions. Changing the doping concentration and width in n1 region affects the characteristics of the structure differently from that of the p1 and p2 regions.     

Controlled turn-on thyristors

In a one or more amplified stage thyristor design it is possible to control the peak current level of all but the final stage with impedance built into the p-base zone. This impedance reduces both the current and the duty cycle of the protected amplifying stage effectively protecting it from undesirable temperature rises during turn-on. A further bonus and perhaps equally important is the fact that the amplifying stage and its current control impedance can be used to reduce and essentially fix the voltage level at which the following stage turns on. This results in a lower voltage, lower stress turn-on of the following stage, and a device essentially protected from di/dt turn-on failure. This paper describes several aspects of controlled turn-on in the context of a 2.6- and 6-kV light triggered thyristor. In particular we discuss selection of the resistor value, the problem of unwanted current control resistor modulation by device current as well as some factors affecting the proper wattage of such resistors. We also discuss the role current control resistors can play in controlling avalanche current from known locations on the device.     

Temperature-Dependent Dynamic Behaviors of Organic Light-Emitting Diode

A systematic investigation of temperature-dependent dynamic behaviors of NPD-Alq₃ organic light-emitting diodes (OLEDs) is carried out. Through an in-depth numerical analysis, it has been found that the luminance decreases and consequently the turn-on voltage increases with decreasing temperature due to a reduction of thermally activated hopping speed, which retards the rise of electroluminescence (EL) upon turn-on as well as the discharge upon turn-off of OLEDs. Most importantly, however, the device efficiency is literally raised as the temperature decreases, a direct consequence of enhanced charge-balance factor. It is also demonstrated that the EL delay upon turn-on is mostly determined by the electron transport through the electron transport layer (ETL), while the fast EL decay (short-lived EL tail) upon turn-off is mainly by the rapid discharge of the steep pileup of carriers at the NPD/Alq₃ interface. The long-lived EL tail is shown to be more pronounced under lower temperatures. In response to a train of voltage pulses, the delay of EL occurring for the first voltage pulse has vanished for the subsequent pulses regardless of temperature due to space charges remaining inside the device after turn-off (in the "off-state"). However, it appears that the pulse-to-pulse interference by the space charge effects is more significant under lower temperatures     

High-speed response of optically-pumped InGaAs/InGaAsP microdisklasers

Transient step-response and small-signal response of intensity-modulated InGaAs/InGaAsP microdisk lasers have been measured for the first time at room temperature. Microdisk lasers operating at room temperature have a measured turn-on delay of 100 ps and a -3 dB small-signal bandwidth in excess of 1.4 GHz     

The di/dt capability of thyristors

This paper describes an experimental investigation of the di/dt failure mechanism of thyristors. The location of the initial turn-on region and the spread of the "on" region were observed on a specially designed thyristor having many monitoring electrodes. The turn-on process was studied for triggering by gate, by breakover, and by dv/dt. In many cases it was found that turn-on occurred at almost the same region, whether it was triggered by breakover or by dv/dt. This area coincided with the final holding position in the turn-off process. The di/dt capability of the thyristor was measured. It was found that the capabilities were almost the same for the three triggering methods. The destruction temperature in the di/dt test was estimated from the area of the burn-out spots and the energy dissipation.     

Comparison of current-voltage characteristics of n- and p-type 6H-SiC Schottky diodes

Current-voltage (I–V) characteristics of n- and p-type 6H−SiC Schottky diodes are compared in a temperature range of room temperature to 400°C. While the room temperature I–V characteristics of the n-type Schottky diode after turn-on is more or less linear up to ∼100 A/cm², the I–V characteristics of the p-type Schottky diode shows a non-linear behavior even after turn-on, indicating a variation in the on-state resistance with increase in forward current. For the first time it is shown that at high current densities (>125 A/cm²) the forward voltage drop across p-type Schottky diodes is lower than that across n-type Schottky diodes on 6H−SiC. High temperature measurements indicate that while the on-state resistance of n-type Schottky diodes increases with increase in temperature, the on-state resistance of p-type Schottky diodes decreases with increase in temperature up to ∼330 K.