The asymmetrical field-controlled thyristor

A new device structure has been developed for field-controlled thyristors. In this structure, the uniformly doped n base of the conventional device has been replaced with a very lightly doped region near the gate and a more heavily doped region at the anode. This change in the base doping profile results in a significant improvement in the tradeoff between the forward-blocking voltage capability and the on-state forward-voltage drop. In addition, the high-resistivity region around the gate area allows the device to pinch off anode current flow at zero gate bias due to the built-in potential of the gate junction. The devices can, however, be triggered to the on-state by applying a small forward gate voltage and exhibit a forward voltage drop in the on-state which is much lower than that of conventional devices. The high resistivity of the channel area between gates also results in these devices having dc blocking gains in excess of 60, which is the highest value achieved in devices of this type. Further, because these devices have been fabricated using conventional planar processing techniques, this structure is suitable for high-volume production with high processing yields.     

Temperature dependence of field-controlled thyristor characteristics

The dependence of the characteristics of field-controlled thyristors upon the ambient temperature has been examined in the range of -30 to 200°C. Unlike conventional thyristors, these devices have been found to continue to exhibit forward blocking capability up to the highest measurement temperature (200°C). In fact, it is shown here that the forward blocking capability as well as the blocking gain improve with increasing temperature with the usual scaling of the leakage current for power devices. The reverse blocking capability is also retained. The forward voltage drop of the device in the conducting state decreases with increasing temperature. This behavior is shown to be similar to that of conventional rectifiers and thyristors operated at high injection levels. Further, the force gate turn-off time of the devices has been found to increase with increasing temperature. This has been correlated with a measured increase in the minority-carrier lifetime. The results of this study demonstrate that field-controlled thyristors are capable of being operated at higher temperatures than conventional thyristors.     

Impulse-doped GaAs power FETs for high efficiency operation

The authors have fabricated impulse-doped GaAs power FETs demonstrating 59% power-added efficiency with 10.4 dB associated gain and 0.33 W/mm at 10 GHz. To the best of their knowledge, this is the highest power-added efficiency ever reported at X-band for a GaAs FET     

Adaptive thyristor power, control circuits

A solid-state circuit is described that provides electronically settable memory control (adaptive control) of thyristor power regulating devices. Electrical power delivered to ac loads, such as lighting, heating, or motors, can be smoothly varied or set to any value from zero to essentially full power by a manual, computer, or remote-controlled application of a voltage pulse to a circuit adapt terminal. Power settings of the circuit can be maintained indefinitely with or without applied power, yet they can be changed quickly (milliseconds) or slowly (dekaseconds) by the application of an appropriate adapt pulse. An adaptive ferroelectric transformer provides the analogue memory capabilities of the control circuit.     

New synchronization method for thyristor power converters to weakAC-systems

An improved approach to obtaining good zero-voltage-crossing signals is presented. These signals are subsequently used as synchronization signals for a phase-controlled thyristor power converter. Detection of accurate zero crossings is possible even when there are large frequency changes, sudden load changes, or large commutation overlap angles. The improved accuracy in the integrity of the zero crossing is obtained by reconstructing a voltage representing the AC source voltage. This voltage is determined from the distorted thyristor converter input voltage, the converter input current, and an online identification of the source impedance using a microcontroller-based adaptive algorithm. The improvement provided by the new zero crossing detection scheme is verified experimentally     

Development of a 2.6-kV light-triggered thyristor for electric power systems

The status of a present Electric Power Research Institute, Inc. (EPRI) funded research program on a directly light-triggered thyristor for high-voltage direct current (HVDC) application is reviewed. An existing 53-mm, 2600-V, 1000-A electrically fired device was suitably modified to be turned on with an incident photopulse of 30 nJ, the basic problem being the retension of a 2000-V/µsdV/dtcapability. Design tradeoffs betweendV/dtand gate sensitivity are discussed as well asdi/dtproblems encountered in turning on a 2-in device with such a small gate signal. Special experiments and design and analysis computer programs have helped in assessing temperature excursion during turn-on and led to improved design with adi/dtcapability approaching that of the original electrically gated device.     

Series operation of Gunn diodes for high r.f. power

Several GaAs Gunn diodes have been made to operate at a single frequency simultaneously in series operation. This, as explained, is an unexpected result and enables the impedance level of these semiconductor devices to be raised and the power level to be increased. This can have important consequences for ultrahigh-power generation.     

Vertical channel field-controlled thyristors with high gain and fast switching speeds

A new, planar, surface-grid, field-controlled thyristor (FCT) structure is described. The structure is fabricated by using orientation-dependent (preferential) etching and selective vapor epitaxial growth to obtain vertical grid walls. The resulting high channel-length-to-width aspect ratio produces devices with high blocking gains and fast gate turnoff speeds. Devices have been fabricated with the capability of blocking more than 1000 V with an applied grid bias of 32 V, and simultaneously exhibiting a low forward voltage drop in the on-state. These surface-grid devices exhibit gate turnoff capability with turnoff times of less than 500 ns at a rated cathode-anode current of 1 A.     

Output power saturation of BH laser under high current operation

Output power saturation of BH lasers under high current operation is analysed and it is concluded that such saturation is due to increase of leakage current through the burying layers. The mechanism of such leakage can be explained by a turn-on model of the bipolar transistor around the active region.     

Instable mechanisms during unclamped operation of high power IGBT modules

The behaviour in terms of robustness during unclamped operations of power IGBT modules is presented. The experimental characterization is aimed to identify the main instable phenomena during unclamped turn-off in power IGBT modules. Several devices of different generations, current and voltage ratings have been analyzed. Thanks to a non-destructive experimental set-up, it is possible to observe instable phenomena without causing the damage of the device under test. In this paper, it is shown that the destructive conditions during unclamped operations are preceded by precursors on the gate side which indicate instable phenomena taking place inside the device. The dependence of the destructive phenomenon on the driver conditions are widely and exhaustively analyzed.     

Comments on `a nonideal macromodel of thyristor for transientanalysis in power electronic systems'

In the above-titled paper by F.J. Gracia et al. (see ibid., vol.37, no.6, p.514-20, 1990) the authors proposed a nonideal macromodel for analog power circuit simulation using SPICE. The model is quite simple and incorporates important second-order effects such as breakover voltage triggering, critical dv/dt, turn-on and turn-off times, threshold gate trigger voltage, and the nonlinear on-state characteristic. The commenter introduces some necessary corrections to the model and proposes some improvements concerning other versions of SPICE and the thermal effects on the breakdown voltage and breakover voltage turn-off characteristics     

Reliability of wire-bonding and solder joint for high temperature operation of power semiconductor device

Thick Al wires bonded on chips of power semiconductor devices were examined for thermal cycle tests, then the bonded joints were cut using microtome method, after that those were observed by scanning electron microscope and analyzed by electron back scattered diffraction. Some cracks were observed between Al wires and the chips, unexpectedly the crack lengths were almost constant for −40/150 °C, −40/200 °C and −40/250 °C tests. It is considered that re-crystallization has been progressed during the high temperature side of the thermal cycle tests.Furthermore, joint samples were prepared using high temperature solders such as Zn–Al and Bi with CuAlMn, Direct Bonded Copper insulated substrates and Mo heatsinks. The fabricated samples were evaluated by scanning acoustic microscope before and after thermal cycle tests. Consequently, almost neither serious damages nor delaminations were observed for −40/200 °C and −40/250 °C tests.     

Optimization of GaAsP/AlGaAs-based QW laser structures for high power 800 nm operation

We present a detailed study of the MOVPE growth of 800 nm diode laser structures based on the combination of a GaAsP quantum well with well-established AlGaAs waveguide structures. By optimizing the strain and thickness of the quantum well highly-reliable diode lasers with low threshold current and high efficiency were demonstrated. 100 μm aperture “broad area” devices mounted epi-side up achieve a CW output power of 8.9 W with a wall-plug efficiency of 50%. These output powers represent record values for diode lasers in this wavelength range. Reliability measurements at 1.5 W and 50°C ambient temperature suggest lifetimes >10 000 h.     

Microwave operation of high power InGaP/GaAs heterojunction bipolar transistors

The first high power demonstration of an InGaP/GaAs heterojunction bipolar transistor is presented. Multifinger selfaligned HBTs were tested at 3 GHz. A maximum output power of 2.82 W CW was obtained for a 600 mu m/sup 2/ emitter area device (4.7 mW/ mu m/sup 2/ power density) with an attendant gain of 6.92 dB; simultaneously, the device exhibited 55.2% power added efficiency, 69.1% collector efficiency and 8.0*10/sup 4/ A/cm/sup 2/ emitter current density.<>     

Thermal effects of the operation of high average power Gunn devices

A lumped thermal resistance model is described for GaAs Gunn and LSA diodes. Thermal resistances are defined for the active layer, contact layer, bond interface, package and heat sink. This permits the calculation of tha maximum device temperature TM= T0+ P ΣiRiand the critical temperature difference across the active layer ΔTA= PRA. A transient analog incorporates thermal time constants Ti= RiCito consider high duty cycle pulsed operation. The carrier mobility is modeled as varying as1/Tin the range from 300 to 500°K. This permits thermal measurements based upon changes in resistance. The thermal calculations were also in agreement with blackbody infrared data. The mobility decline with temperature is shown to act as a link between the thermal profile and device performance. A thermally induced avalanching point, as well as device efficiency, are influenced by the peak-to-valley current ratio. This ratio is reduced from its theoretical value of over 2:1 by the active layer resistivity ratiobar{partial}/partial_{max}. Thus thermal gradients in the active layer act to create mobility gradients which alter the observed peak-to-valley ratio. The steps necessary for maintaining high average power efficient operation require low thermal resistances to minimize the active layer temperature gradients and a high current drop back ratio. Total experimental thermal resistances of 6.5°C/watt for an X-band CW diode and 17°C/watt for a thick LSA diode have been observed and fit the model presented.     

Differential switching operation of vertical cavity laser with depleted optical thyristor for optical logic gates

Optical logic gates with AND, OR, and INVERT functionality are demonstrated by the monolithic integration of a vertical cavity laser with depleted optical thyristor. All kinds of logic functions (AND, OR, NAND, NOR, and INVERT) are experimentally demonstrated using a differential switching operation scheme by simply controlling an intensity of a reference input light     

Analytical expressions for carrier distribution in a wide thyristor base under high injection

For calculating the carrier distribution in the base of a wide thyristor, the dependency of the ambipolar mobility on the carrier concentration and the influence of current are taken into account to obtain analytical approximations which are useful as a start for an exact computer solution.     

可控硅调压激光器电源的新型同步触发电路

本文介绍一种新的三相全控桥调压电源同步触发方案。在这一新模式中，用光电隔离器代替传统的三相同步变压器使同步方式发生了根本变化，光电隔离器输出的信号经整形后数字信号的方式进     

高速硅闸流管的原理与制造方法

本文介绍高速硅闸流管简要原理制造方法。该器件可用于激光通信、引爆（信）、测距、小型雷达、模拟射击、游戏枪、车辆防碰撞等方面，也可用于各种脉冲电源及脉冲开关上。     

Thermal analysis of high power LED packages under the alternating current operation

In this paper we describe a novel thermal characterization method of GaN-based Light Emitting Diode (LED) package driven under the Alternating Current (AC) mode. The result was compared with the results from the thermal analysis for LED package operated under the Direct Current (DC) condition. Different from the DC condition, the junction temperature rise with the operation time of LED package was exhibited in a band formation. Finite Volume Method (FVM) was utilized to calculate the thermal performance of LED package under the AC condition using the input power extracted from the output current and voltage from the AC power supply. The experimental result was in a good agreement with the simulation data.