金属氧化物半导体控制晶闸管的di/dt优化

金属氧化物半导体控制晶闸管(MCT)相比于绝缘栅双极型晶体管(IGBT)具有高电流密度、低导通压降和快速开启等优势,在高压脉冲功率领域具有广阔的应用前景.作为脉冲功率开关,MCT开启过程对输出脉冲信号质量有很大影响.采用理论分析并结合仿真优化重点研究了MCT开启瞬态特性.通过对MCT开启过程进行详细地理论分析推导,给出了MCT开启过程中阳极电流和上升时间的表达式.结合Sentaurus TCAD仿真优化,将MCT开启过程中电流上升速率(di/dt)由40 kA/s提升至80 kA/s,极大地改善了器件开启瞬态特性.最后,总结提出了提高器件开启瞬间di/dt的设计途径.     

The application of saturable turn-on snubbers to IGBT bridge-legcircuits

The turn-on loss of high-speed insulated gate bipolar transistors (IGBTs) accounts for a significant proportion of the total switching energy. In many applications, this loss is increased by the energy associated with diode reverse recovery of current. Such energy is absorbed by the IGBT switch at high voltage. Linear turn-on snubber inductors may be used to control the turn-on loss, diode reverse recovery, and electromagnetic compatibility (EMC). These snubbers have the disadvantage of involving substantial stored energy that must be reset, normally by dissipation. An alternative is to use a saturable turn-on snubber inductor, which stores substantially less energy than a linear inductor. In this paper, the suitability of saturable turn-on snubber inductors for use with IGBTs is investigated, and possible circuit topologies for single-ended and bridge-leg applications are proposed. Mathematical analysis, simulation, and practical results are presented for the saturable inductor turn-on snubber circuit topologies     

Turn-on delay for Josephson logic devices with high damping

Josephson logic devices exhibit, before switching from superconducting to voltage state, a turn-on delay which depends on current overdrive and damping coefficient. A novel expression describing turn-on delay for heavily damped circuits is proposed. A comparison with numerical calculation is made. As an example of application for this expression, the turn-on delay appearing in the simulation of a damped logic gate switching is discussed.     

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     

一种用于提高ESD保护器件开启速度的新型变化横向基区 掺杂结构双触发晶闸管

The turn-on speed of electrostatic discharge （ESD） protection devices is very important for the protection of the ultrathin gate oxide. A double trigger silicon controlled rectifier device （DTSCR） can be used effectively for ESD protection because it can turn on relatively quickly. The turn-on process of the DTSCR is first studied, and a formula for calculating the turn-on time of the DTSCR is derived. It is found that the turn-on time of the DTSCR is determined mainly by the base transit time of the parasitic p-n-p and n-p-n transistors. Using the variation lateral base doping （VLBD） structure can reduce the base transit time, and a novel DTSCR device with a VLBD structure （VLBD_DTSCR） is proposed for ESD protection applications. The static-state and turn-on characteristics of the VLBD DTSCR device are simulated. The simulation results show that the VLBD structure can introduce a built-in electric field in the base region of the parasitic n-p-n and p--n-p bipolar transistors to accelerate the transport of free-carriers through the base region. In the same process and layout area, the turn-on time of the VLBD DTSCR device is at least 27% less than that of the DTSCR device with the traditional uniform base doping under the same value of the trigger current.     

Turn-on jitter of zero-biased nearly single-mode VCSEL's

The turn-on jitter of zero-biased nearly single-mode vertical-cavity surface-emitting lasers (VCSEL's) is experimentally investigated. Since during the turn-on event both the dominant and the suppressed polarization are exited, an analytical expression describing the probability density function of the turn-on delay for a single-mode VCSEL is derived, which accounts for both polarizations. The measurement results and the theory are in good agreement as long as the VCSEL is transversal single-mode     

New fast turn-on speed SCR device for electrostatic discharge protection

A new SCR with the variation lateral base doping (VLBD) structure (VSCR) is proposed to improve the turn-on speed for electrostatic discharge (ESD) protection. The turn-on speed of the SCR was determined mainly by the base transit time of the parasitic p-n-p and n-p-n transistors of the SCR, and the VLBD structure can reduce the base transit time of the bipolar transistors to improve the turn-on speed of the SCR. The experimental and simulation results show that the turn-on time of the VSCRs with the VLBD structure is 12% less than that of the MLSCR with the traditional uniform base doping without adding extra process masks and increasing the chip area.     

一种用于静电保护的快速开启SCR器件

提出了一种用于提高静电泄放(ESD)保护器件开启速度的SCR器件(VSCR)。VSCR采用了新型的横向基区变掺杂结构(VLBD),其开启速度主要由寄生p-n-p和n-p-n晶体管的基区渡越时间决定,使用VLBD结构能够减小寄生双极型晶体管的基区渡越时间,从而提高SCR器件的开启速度。实验结果证明,在不增加掩膜版数量和芯片面积的前提下,相比于传统均匀基区掺杂的MLSCR器件,采用VLBD结构的VSCR器件的开启速度能够提高12%。     

Drain-voltage dependence of IGFET turn-on voltage

The turn-on voltage (or threshold voltage) characteristic of an enhancement-type insulated-gate field-effect transistor (IGFET) in its pentode operation region, is analyzed based on a simple model. A new definition for the turn-on voltage at just-saturated state is given and a new simple formula for the turn-on voltage shift in IGFETs pentode operation region, is deduced. This assumes a reduction of gate-induced bulk charge under the influence of the drain voltage. Agreement of the theory with experiment is good.     

Turn-on jitter in semiconductor lasers with moderate reflectingfeedback

Numerical simulations are used to investigate the impact of moderate external feedback on the turn-on timing jitter inherent in directly modulated semiconductor lasers. Enhanced turn-on jitter is found to be due to the feedback-induced intensity noise     

High-Gain Low Turn-On Voltage AlGaAs/GaAsNSb/GaAs Heterojunction Bipolar Transistors Grown by Molecular Beam Epitaxy

AlGaAs/GaAsNSb heterojunction bipolar transistors (HBTs) with low turn-on voltage have been fabricated. The turn-on voltage of the device fabricated from an as-grown sample is ~180 mV lower than that of a conventional AlGaAs/GaAs HBT. The effect of rapid thermal annealing on device performance is an increase in the gain from ~8.5 to ~20. However, the knee voltage of the annealed sample (~3 V), as well as the turn-on voltage, is also higher compared with that of the as-grown sample (~1.5 V).     

Anomalous turn-on voltage degradation during hot-carrier stress inpolycrystalline silicon thin-film transistors

In this letter, we present experimental data showing that hot-carrier stress in laser annealed polycrystalline silicon thin-film transistors provokes an anomalous turn-on voltage variation. Although under various hot-carrier stress intensities the maximum transconductance degradation shows the same power-time dependent law, turn-on voltage can exhibit different behaviors. This observation lead to the conclusion that turn-on voltage depends on two different degradation mechanisms: injection of hot carriers into the gate oxide and degradation of grain boundaries. We show that these two mechanisms may be distinguished since they obey different power-time dependent laws as a function of stress duration     

温控晶闸管导通温度的设计

本文从温控晶闸管结构模型出发,建立一组相应的方程,获得了温控晶闸管导通温度与离子注入剂量的关系。通过精确控制离子注入剂量,器件可以获得预期的导通温度。     

Turn-on phenomena in optically and electrically fired thyristors

An analytical solution of the time-dependent transport equation including surface recombination and optical injection for a diffused thyristor base is presented. By means of the classical two-transistor model, the turn-on transient may be predicted. Apart from the influence of technological parameters like base width, doping profile, and diffusion length, the effect of optical versus electrical injection as well as surface recombination are discussed. Surface recombination may significantly influence the optical turn-on threshold. Despite the rigorous simplicity of the model, the dynamic turn-on behavior of an optically fired high-voltage thyristor is in very good agreement with the experiment. The data, being presented for a wide range of parameters, are useful for practical design.     

Timing jitter in semiconductor lasers under pseudorandom wordmodulation

Timing jitter of semiconductor lasers under pseudorandom word modulation was studied at 1 Gb/s. For lasers biased above threshold the timing jitter was Gaussian in distribution, with a turn-on timing jitter amplitude τ=2σ=±6 ps. For lasers biased below threshold, the turn-on timing jitter showed two peaks of Gaussian distribution, with an amplitude τ=60±10 ps and separated by about 80 ps. This phenomenon is due to a pattern-dependent effect of the laser turn-on delay. Theoretical calculations show that for data transmission above 2.2 Gb/s, the laser has to be biased above threshold to avoid excessive (>0.5 dB) jitter-induced power penalty     

Transient characteristics of latch-up in bulk CMOS

Transient characteristics of the latch-up turn-on process in bulk CMOS are investigated. A measurement technique that evaluates the threshold trigger pulse current of latch-up and also observes latch-up turn-on transient waveforms is established. Through the comparison between experimental data and precise circuit simulation results, the main factors that determine transient latch-up characteristics are clarified as the base-emitter diffusion capacitors.     

Low turn-on voltage InGaP/GaAsSb/GaAs double HBTs grown by MOCVD

A novel InGaP/GaAs_0.92Sb_0.08/GaAs double heterojunction bipolar transistor (DHBT) with low turn-on voltage has been fabricated. The turn-on voltage of the DHBT is typically 150 mV lower than that of the conventional InGaP/GaAs HBT, indicating that GaAsSb is a suitable base material for reducing the turn-on voltage of GaAs HBTs. A current gain of 50 has been obtained for the InGaP/GaAs_0.92Sb_0.08/GaAs DHBT. The results show that InGaP/GaAsSb/GaAs DHBTs have a great potential for reducing operating voltage and power dissipation     

Ultralow-voltage boron-doped diamond field emitter vacuum diode

A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp² content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters     

The dV/dt capability of MOS-gated thyristors

In this paper, a detailed study of the dV/dt capability of MOS-gated thyristors is performed. It is shown that in addition to the conventional mode of dV/dt-induced turn-on in thyristors, termed the intrinsic mode, there exists another distinct mode of dV/dt-induced turn-on, peculiar to the MOS-gated thyristor structure, which the authors term the extrinsic dV/dt mode. The effective dV/dt capability is determined by both modes and is degraded by the presence of an external gate-cathode resistance and parasitic gate-anode capacitance. The existence of these two modes of dV/dt-induced turn-on is demonstrated experimentally, and the effect of device parameters on the dV/dt capability is studied     

Programmable input power factor correction method for switch-moderectifiers

A programmable method for single- and three-phase switch-mode rectifiers (SMRs), operating with discontinuous current conduction to control input power factor close to unity, is presented. Single-phase SMR operation is based on variable turn-on time, while three-phase SMR operation is based on constant turn-on time