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Proceedings of the IEEE

Issue 8 • Date Aug. 1967

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Displaying Results 1 - 25 of 79
  • [Front cover and table of contents]

    Page(s): c1
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    Freely Available from IEEE
  • Scanning the issue

    Page(s): 1247 - 1248
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    Freely Available from IEEE
  • Silicon power device material problems

    Page(s): 1249 - 1271
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    The limitations imposed on the performance of large-area p-n junction devices by the size and quality of the silicon material are reviewed. It is shown that material quality problems--such as nouniform resistivity, foreign particulate matter, microdefects, dissolved oxygen, and various crystallographic defects--represent real limitations on device performance and yields; however, the effects of process-induced defects--such as diffusion- or stress-induced dislocations, diffusant precipitation, heavy metal precipitation, and interface degradation--often obscure, or even overwhelm, the effects of the grown-in defects. The importance of the interaction of process-induced defects with grown-in defects, and particularly the interaction of heavy metals with defects, foreign particulate matter and dissolved oxygen, has been emphasized by the results of recent investigations. The need for defect-free processing techniques in obtaining information on the effects of grown-in defects is discussed. Representative studies of the effects of defects on device performance are listed. New techniques for studying defects are reviewed with reference to results of interest to silicon device technology. Some growth techniques which may be helpful in eliminating certain material quality problems are discussed briefly. View full abstract»

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  • Second breakdown—A comprehensive review

    Page(s): 1272 - 1288
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    This paper is a comprehensive review of the published literature dealing with the phenomenon of second breakdown in semiconductor devices and the problems it creates in the design, fabrication, testing, and application of transistors. View full abstract»

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  • Power thyristor rating practices

    Page(s): 1288 - 1301
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    The power thyristor is the most important semicoductor device used in the control of electric power. An explanation of thyristor ratings and rating presentation is required for the complete understanding and successful application of these devices. This paper not only explains the meaning of thyristor temperature, voltage, current, and gate ratings but also presents insights into how these ratings are developed. Both the semiconductor controlled rectifier (SCR), which is properly called a reverse blocking triode thyristor, and the bidirectional thyristor rating methods are discussed. SCR rating are further divided into those applying to phase control applications at power frequencies and those applying to high repetition rate inverter and pulse current appications. View full abstract»

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  • The di/dt capability of thyristors

    Page(s): 1301 - 1305
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    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. View full abstract»

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  • Behavior of thyristors under transient conditions

    Page(s): 1306 - 1311
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    The capability of gate-triggered thyristors to withstand steep wavefront, high-current pulses (i.e., di/dt capability) is a function of both junction temperature and frequency of operation. Localized internal heating occurs during turn-on and may lead to thermal runaway. The conditions required for this to occur have been determined by destructively testing many devices. The initial conducting area of a thyristor largely determines di/dt capability, which is not necessarily related to the size of the device but is a function of the design of the gate region. Gate drive is very important for determining the di/dt capability of a thyristor having a conventional gate design. Two devices which have been designed to increase the initial conducting area are discussed. One of these devices, if improperly designed, can lose its effectiveness with high gate drive. This characteristic can be studied by observing the reverse recovery current immediately following short forward current pulses. View full abstract»

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  • Bidirectional triode thyristor applied voltage rate effect following conduction

    Page(s): 1312 - 1317
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    This paper describes the bidirectional thyristor commutation effect which involves the rate at which off-state voltage can be applied following current flow. This effect is contrasted to the circuit commutated turn-off time effect associated with semiconductor controlled rectifiers. To help describe the commutation effect in bidirectional devices, two common circuit applications are discussed. A test method is introduced for characterizing the commutation behavior as a function of all operating conditions. A great deal of quantitative information about the commutation effect is presented for a typical medium current bidirectional triode thyristor. View full abstract»

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  • p-n-p-n charge dynamics

    Page(s): 1318 - 1330
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    A simple unified charge model applicable to both unsaturated and saturated p-n-p-n dynamic behavior is analyzed. Expressions are obtained for three important dynamic conditions: di/dt prior to saturation, voltage drop during turn-on, and reverse current during recovery. Comparison with measurement shows that interdigitated gate p-n-p-n devices match one-dimensional turn-on theory and closely approximate the behavior of p-i-n rectifiers under similar pulsed conditiom. The major analytical simplifications of the one-dimensional theory are examined in the Appendixes. The limitations imposed by these simplifications can be avoided by use of numerical integration techniques. View full abstract»

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  • Reverse recovery processes in silicon power rectifiers

    Page(s): 1331 - 1354
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    The present review gives an account of a number of investigations that have been recently carried out in the Semiconductor Laboratory Pretzfeld, Siemens AG. The switching processes in power rectifiers from the forward into the reverse state differ greatly from the corresponding process predicted by low-level theory. This result is caused not only by the fact that the conditions are different for high injection, but in addition, the sweeping out of the charge carriers takes place from two sides, owing to the nearly uniform concentration distribution in the forward state. Because of the unequal electron and hole mobilities, the impurity distribution on the side of the p contact is of much greater importance than at the n contact; if there is no p-n junction on this more important side, then the stored change can be swept out without much voltage buildup (example: rectifiers from uniformly doped p material). If, on the other hand, a p-n junction lies before the p contact (example: rectifiers from uniformly doped n material) then tbe reverse recovery current decays soon but slowly, and the switching process takes a longer time. This fact also contributes to the relatively long turn-off time of the thyristors. View full abstract»

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  • Protection of semiconductor devices, circuits, and equipment from voltage transients

    Page(s): 1355 - 1361
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    In this paper a survey is presented of the means that can be applied to the suppression of voltage transients that can affect the reliability of equipment and systems employing semiconductor devices. Consideration is given to some of the ways transients are generated, their duration and magnitudes, and the approach taken in the military standard MIL-STD-704 in confining the power supply characteristics within definite limits which must be tolerated by the utilization equipment. Emphasis is placed on the various techniques--their advantages and limitations--that can be applied in suppressing transients generated from 28-volt dc power supplies. In addition, various device approaches used to limit voltage transients to rectifier diodes are also presented. View full abstract»

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  • Power absorption capability of punch-through devices

    Page(s): 1361 - 1365
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    The power absorption capability and high-current characteristics of silicon high-voltage punch-through structures were investigated. Impact ionization was observed in the devices using 100- and 75-ohmċcm base material. The transient power absorption capability of these structures was found to be less temperature-dependent than that of avalanche devices. With proper surface contouring, a power absorption capability of 48 kW/cm2at 10 µs was achieved at a junction temperature of 26°C and 38 kW at 200°C for devices made of 350-ohmċcm base material. View full abstract»

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  • Graphical analysis of the I-V characteristics of generalized p-n-p-n devices

    Page(s): 1366 - 1374
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    A new form of the basic equation for the I-V characteristics of a generalized p-n-p-n device is derived. Approximations are then introduced to obtain a simplified basic equation in which all current-dependent terms appear on one side of the equation and all voltage-dependent terms on the other. A graphical technique for solving the simplified device equation is then described and used to develop and illuminate the family resemblance among a large number of related p-n junction devices; viz., the p-n junction diode, the p-n-p diode, the p-n-p transistor, the p-n-p-n diode, and the p-n-p-n triode. View full abstract»

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  • A theory and some characterisitcs of power transistors at high-level conditions

    Page(s): 1375 - 1383
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    The concentration of injected carriers is large compared with the impurity doping concentration in the base region of a power transistor operating at high level. Carrier concentration and characteristics of a two-dimensional transistor model are calculated for this case. Emitter and base contacts are in the form of strips. Most of the injected emitter current reaches the collector while the remainder recombines in the slightly doped base region under the emitter, resulting in a current in the highly doped base contact. In addition, a recombination current generated in the base region under the base contact is added to this base current and results in a decrease of current gain. In order to analyze the base recombination current, a special transistor with divided collector contacts was prepared. In this way, the collector current due to the region under the emitter contact can be separated from the collector current due to the region under the base contact. The presented theory could be verified. Additional corrections are necessary, however, in the direction of the current in the slightly doped base region. View full abstract»

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  • The saturation characteristics of high-voltage transisitors

    Page(s): 1384 - 1388
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    It is shown that the saturation characteristic of high-voltage NPvN transistors can only be explained by a lowering of the v-layer resistance due to conductivity modulation. A semi-quantitative model is developed which explains this modified saturation region. An experimental method of isolating the resistive portion of the external collector-base (CB) voltage is presented. The results verify that the CB junction may be forward-biased even when the characteristic seemingly indicates that the transistor is unsaturated. Data is also presented showing how variations in collector resistivity and thickness alter the saturation region. View full abstract»

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  • The potential and carrier distributions of a p-n-p-n device in the ON state

    Page(s): 1389 - 1400
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    The potential and carrier distributions of a p-n-p-n device in the ON state are measured by electrical and optical probing techniques. The measurements are compared with numerical calculations of the potential and carrier distributions and the current-voltage characteristics as a function of device temperature. The calculations are based upon an analysis of the p-n-p-n device at high current densities using an abrupt junction model and including the effects of carrier-carrier scattering, conductivity modulation, and the dependence of emitter efficiency upon current density. The conditions under which the p-n-p-n device may be approximated by a p-n-n+device are also considered. The range of applicability of the results includes all ON currents of practical interest in a p-n-p-n device. View full abstract»

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  • The forward characteristics of thyristors

    Page(s): 1400 - 1408
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    A theory on the forward V-I characteristics of P+-P-N-P-N+thyristors is proposed. Taking the minority carrier lifetime in the base region into account, the effects of the device structures on the forward characteristics are discussed on the following three cases: 1) low-level operation, 2) middle-level operation, and 3) high-level operation. At middle-level operation, the term that is independent of current and, at high-level operation, the √I dependency, appears in the forward characteristics of the thyristors. The general theory is illustrated by reference to experimental results on silicon-controlled rectifiers. View full abstract»

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  • High-voltage planar p-n junctions

    Page(s): 1409 - 1414
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    A concentric ring junction has been devised to prevent surface breakdown of a planar junction. By properly choosing the spacing between the main junction and the ring, the ring junction acts like a voltage divider at the surface. In addition, the ring junction minimizes the effect of the junction curvature at the periphery of a planar junction. Devices fabricated with three such rings showed breakdown voltages of 2000 and 3200 volts on n-type silicon with impurity concentrations 6.5 × 1013and 2.5 × 1013cm-3, respectively. That the structure operated as proposed was corroborated by comparison of the reverse leakage current with a one parameter fit to a theoretically calculated current obtained from the approximated volume of the space charge regions. These results together with the photo response measurements indicate that the field-limiting ring junction can be used successfully to obtain high-voltage planar p-n junctions. View full abstract»

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  • High-power pulsed GaAs laser diodes operating at room temperature

    Page(s): 1415 - 1419
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    The fabrication and characteristics of a high-power GaAs injection laser for room-temperature operation are described. A single laser emits 70 watts peak power from one facet at four times the threshold current. The diodes are fabricated from epitaxial wafers prepared by the solution-growth process. Scaling from work on low-power (7-watt) units to this high power has been accomplished by increasing the junction width, which requires general improvement in the crystalline quality and in the control of the doping. Data are given on the effect of doping density, crystal quality, and imperfections near the junction, as well as junction width. The reduced yield in high-power diodes, of which only one-third from a single batch give the desired output, is associated with filamentary lasing and with super-radiant walk-off modes, neither of which is under full control. Preliminary data on life tests show that long-lived units can be made, but that apparently identical units from the same batch show wide variations in the rate of degradation. View full abstract»

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  • Coherent amplification characteristics of a GaAs phased array

    Page(s): 1420 - 1425
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    The coherent amplification properties of antireflective coated GaAs diodes are considered for application to a phased array amplification scheme. The developmemt and design characteristics of a ten-element array system are discussed. An experimental diode array possessing good electrical and spectral match among diodes and excellent thermal dissipation is shown to provide optical gains, for main master laser modes, of at least 13 dB per array diode after coating. Temporal and spatial coherence within a GaAs laser spot, approximately 35 µ wide, is found to be adequate for array amplification purposes. The effects of array amplification on an incident coherent beam are evaluated by comparing predicted fringe patterns with observed interference patterns. The coherence of the incident beam is shown to be preserved during the amplification process. View full abstract»

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  • Consumer applications of power semiconductors

    Page(s): 1426 - 1434
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    Power semiconductors--transistors, thyristors, and rectifiers --all have found widespread application in the three major consumer markets --automotive, entertainment, appliance. These devices have been developed to provide low-cost solutions to existing needs. In the mid-1950's, the germanium power transistor, as used in hybrid auto radio sets, was the sole power semiconductor represented in a consumer application. It was soon joined by rectifiers designed for power supply use in line operated television sets. Near the turn of the decade, the development of press-fit alternator rectifiers created a completely new consumer use. Today these devices in only slightly modified form are used for the original application as well as a host of allied uses. Recently, power thyristors expressly designed for appliance controls have opened up entirely new concepts in this market area. Upwards of 200 million [1] power semiconductors are used in consumer applications each year. As technology progresses, indications are that this market will more than double in the next few years as TRIAC [2], [3] and QUADRAC open new appliance markets, as high-voltage power transistors phase into television, and as alternator regulators switch to large area integrated circuitry. Whether the market is automotive, appliance, or entertainment, and whether the application is audio, phase control, or switching, the penetration of power semiconductors into consumer use has followed a history of applying advanced device technology directly to a market opportunity. The successes have always been the result of providing lower costs, a better way, or in adding value to the consumer product. This paper will discuss the features of consumer power devices and their applications that make them different from their predecessors. View full abstract»

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  • Flat packaged thyristor assembly for high-voltage application

    Page(s): 1434 - 1440
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    Applications for high-power thyristors continue to increase at an accelerated pace. The circuit designer (user) and device designer (producer) have attained a high degree of maturity in their respective areas of interest and in the joint effort of mating the device to this application for optimum performance. It is the purpose of this paper to describe and analyze recent developments in the device encapsulation design area which are directed to tailoring thyristors for high-power, multikilovolt service. The use of conventional thyristors in an application requiring, e.g., 100 kilovolts holdoff capability, presents a number of problems. The physical layout alone is quite extensive, considering perhaps 100 devices plus balancing networks, anode reactors, firing circuitry, etc. Also, one must properly cool the aggregate of units which may be dissipating on the order of 25 kilowatts. A thyristor encapsulation and stack module specifically designed to fulfill the requirements of high-power multikilovolt applications are described. Compression bonded encapsulation and integral heat sink design principles are employed. Stack modules for forced air cooling and oil cooling applications are reviewed. Particular note is made of a radar modulator application and, more recently, the projected use in high-voltage dc transmission line converter stations. Mechanical and thermal design features are emphasized in the review. Potential application of the devices in conventional bridge-type arrays is explored. View full abstract»

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  • Use of power semiconductors to control locomotive traction motors in the French national railways

    Page(s): 1441 - 1448
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    The application of semiconductor rectifiers and thyristors in the control of power to ac, dc, and diesel powered locomotives in the French National Railways is presented. A total of 260 locomotives have been equipped with 60 000 semiconductor rectifiers since 1959. The failure rate of these rectifiers has been 0.12 percent or 1.35 percent for every million kilometers traveled. Four locomotives have been equipped with thyristor control circuits and it is anticipated that all future single-phase ac powered locomotives will use thyristors. View full abstract»

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  • Oscillator-circuit thyristor converters for induction heating

    Page(s): 1449 - 1453
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    For the induction heating of metals it is advisable in many cases to use higher frequencies. So far, the input required has been supplied by rotary converters or high-vacuum tubes. Recently, static converters with thyristors have also been employed. Equipment already installed is described, and details are given on the considerations leading to the solution adopted. View full abstract»

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