Breakover Voltage Research Articles

A high-voltage light-activated thyristor with a novel over-voltage self-protection structure

A high-voltage self-protected thyristor with a well structure formed in its p-base layer whose operation is based on avalanche breakdown is described. The device structure is simple and easy to fabricate compared to other avalanche-type devices. Numerical analyses and experiments demonstrate that the breakover voltage can be controlled by varying the well diameter and/or its depth. The breakdown voltage fluctuation of the device is 10% when the junction temperature is varied from 23 to 100 degrees C. The device is turned on safely at 7300 V. >

Switching characteristics of MINPN devices

The I– V characteristics of the MINPN devices have been studied with the focus on the physical processes in the switchings. The study consists of computer simulation and experimental measurements, both of which show that these devices can exhibit one-state as well as two-state switchings. Such switchings are attributed to the regenerative process of the avalanche of the reverse PN junction with one or multiple current gains of the two composite NPN and MINP transistors. The MIS minority injection plays an important role in determining the switching characteristics of the device. Experimentally the breakover voltage and the hold-on voltage of this device are observed to be adjustable by applying base voltages. This can be considered as another evidence for the increased minority injection of the MIS structure.

An optically controllable negative resistance circuit constructed with optocouplers

An optocoupler with a Darlington configuration at the output side can be used as a one port active device with a current-controlled negative resistance by simply connecting the input and output sides in cascade. The author proposes an optically controllable negative-resistance circuit constructed with optocouplers. The breakover voltage and the holding current of the negative-resistance characteristics can be controlled widely with two external light inputs. Hence, the circuit may be applied to optronic functional switching operations. It is demonstrated that an optically controlled relaxation oscillator can be easily constructed using the circuit, and that applications of the relaxation oscillator to a light modulator and an optical Schmitt trigger can be realized by simple circuit configurations.

Electrical properties of multi p-n junction devices

The electrical properties of multi p-n junction devices are analyzed. It is found that this type of device possesses bistable characteristics similar to that of a Shockley diode and thus provides an alternative realization of devices for switching applications. The inherently greater current gains involved in the operations of such a device yield in principle higher breakover voltages and higher holding currents. Furthermore, the incorporation of heterostructures in this device introduces a new degree of freedom in tailoring their switching characteristics. Multi p-n heterojunction devices operating as SCR lasers were fabricated, and the experimental results are presented.

An optically-coupled crosspoint array with high dv/dt capability and high gate sensitivity

A 2/spl times/4 optically-coupled economical crosspoint array for the telephone speech path with a high breakover voltage (>450 V), high dv/dt capability (>200 V/0.1 /spl mu/s), and high gate sensitivity (<5 mA) is described. This has been achieved by a new device structure with a double-gate MOSFET and RC discharge circuitry formed on a p-n-p-n element. This MOS associated circuitry for dv/dt improvement is referred to as `MAC' p-n-p-n elements with MAC can be separated from each other with a new simple isolation technique called `canal isolation' which facilitates low manufacturing cost. Both p-n-p-n elements and LEDs are bonded face-down on a 44 pin chip carrier ceramic package with bump electrodes which again allows low manufacturing cost. The MAC enables independent control of the dv/dt capability and the gate sensitivity. The authors show the MAC performance in dv/dt improvement and various evaluations of MAC, including computer simulation. High breakover voltage technology and some processes for forming the gate-to-cathode resistor R/SUB GK/ for devices with MAC are discussed. This new optically-coupled crosspoint array with MAC makes possible a high-performance direct interface with conventional telephone sets.

An optically-coupled high-voltage p-n-p-n crosspoint array

A solid-state crosspoint array compatible with electromechanical switches has been developed in order to realize high-performance telephone exchange networks. The optically-coupled high breakover voltage crosspoint array discussed in this paper has achieved complete isolation of the speech path from the triggering circuit while it can be triggered directly by a transistor-transistor logic (TTL) level signal from the control circuit. The crosspoint array has a unique photo-coupling structure which allows four p-n-p-n elements to be triggered effectively by only one LED, maintaining up to 200 V/0.1 /spl mu/s dv/dt characteristics. It provides breakover voltage of up to 450 V, gate trigger LED current less than 20 mA, ON-state resistance within 4.5 /spl Omega/ and OFF-state capacitance less than 7 pF. The matrix arrangement is a 1/spl times/4 configuration; it is composed of a two wire bidirectional circuit and packaged in a 16-pin ceramic DIP. These device characteristics make possible the realization of solid-state crosspoint array practically compatible with the conventional electromechanical switch, particularly meeting requirements of miniaturization, low-power dissipation, and inexpensive construction. Accordingly, direct interface with conventional telephone sets is possible.

Enhancement- and depletion-mode vertical-channel m.o.s. gated thyristors

A new gate structure is described for power thyristors which uses the m.o.s. field effect to control the anode breakover voltage. Experimental devices have been fabricated using a V-groove etched in (100) oriented wafers and forming the gate in these grooves. Both enhancement- and depletion-mode devices have been demonstrated.

A thyristor protected against di/dt failure at breakover turn-on

The principle and the operation of a thyristor that can be turned on by exceeding its breakover voltage are described. The principle uses the concept of an auxiliary thyristor amplifying the small breakover current to a large gate current for the main thyristor. In this arrangement the breakover turn-on has to occur first in the auxiliary thyristor. This is ensured by a doping of the n-base of the auxiliary thyristor which is higher than that of the n-base of the main thyristor. Time resolved infrared photographs of the breakover turn-on are presented. Also, infrared photographs of the breakdown radiation from p- n- p structures are used to give a survey on the starting silicon which already contains the inhomogeneous doping.

An optronic negative resistance circuit

A negative-resistance circuit has been constructed with the combination of a p-n-p junction transistor, a light emitting p-n diode and a n-p-n photo transistor. The circuit provides negative-resistance voltage-current characteristics in both for increasing and decreasing the positively applied voltage, and holds a facility to obtain external control optically. The breakover voltage can be set at a desired value according to the adjustment of bias resistances for the p-n-p junction transistor.

Electroluminescent shockley diodes of GaAs and GaAsl−x, Px

GaAs and GaAs1−xPx p-n-p-n Shockley diode structures have teen prepared by an epitaxial vapor-phase growth technique. The two-terminal devices exhibit a negative-resistance I-V characteristic, which allows them to be used as an electroluminescent diode with a built-in latching capability. The GaAs diodes have breakover voltages between 2 and 30 V at room temperature, and switching characteristics which depend appreciably on the impurity concentrations and thicknesses of the two inner layers. After breakdown, the diodes emit near-bandgap infrared radiation with external quantum efficiencies as high as 0.39%. The emission spectra have been found to consist of two peaks, one corresponding to recombination in the innermost n-layer, and the other corresponding to recombination in one of the two p-type layers. The emission for the GaAs diodes occurs uniformly over the entire surface area. For GaAs1−x Px, the type of compositional grading used between the GaAs substrate and the p-n junction regions has been found to dramatically affect the I-V characteristics and switching capabilities of the Shockley diodes. Most importantly, the emission from the GaAs1−xPx devices occurs in small filaments for alloys with x ≃ 0.18. At high currents, the filaments form an orthogonal grid pattern parallel to {110} planes, thereby demonstrating a clear relationship to lattice-misfit dislocations generated during compositional grading.

GaAs:Mn double-injection devices

The breakover voltage of double-injection devices is calculated and is shown to be a constant at low thermal hole densities but a monotonically decreasing function of thermal holes at high densities. The results are applied to GaAs:Mn double-injection devices to explain their relatively low experimental breakover voltage. The radiant flux from the GaAs:Mn devices is measured and shown to exhibit a decreasing quantum efficiency with increasing current due to a carrier sweep out effect.

GaAs vapor-grown Shockley diodes and semiconductor-controlled rectifiers

GaAs vapor-grown n-p-n-p structures have been prepared from which two-terminal negative-resistance Shockley diodes and three-terminal semiconductor controlled rectifiers (SCR's) have been fabricated. For basewidths between 1 and 5 µm, these devices have a breakover voltage between 5 and 20 V, a forward voltage of about 1.2 V, and switching times on the order of 1 to 10 ns. Uniform near-bandgap electroluminescence with external quantum efficiencies up to about 0.2 percent is obtained at room temperature. The SCR's fabricated from the vapor-grown structures exhibit classical latching behavior upon application of a gating pulse to either of the interior layers.

Improvement of the Incubator-Respirator

The article by Somerwill, Brown, and Sweet in this issue1 is timely for several reasons. It is quite clear that the incubator-respirator was not adequately tested by the manufacturer before being placed on the market. Several years before converting to continous negative pressure (CNP) use, we found it necessary to make certain modifications in order to prevent equipment failure and the manufacturer was notified about our problems and solutions. The triac semi-conductor was changed from an SC45B to an SC45D which has a maximum breakover voltage of 400 V.

Single injection, double injection and negative resistance in gold-doped high-resistivity silicon

A simplified explanation is given for negative resistance in a semiconductor containing deep-lying donor and acceptor levels. A simple equation is derived for the breakover voltage and is verified by experimental studies of single and double-injection currents in gold-doped silicon.

Germanium Diode and Triode PNPN Switches

Germanium PNPN switches having forward breakover voltages in ths range of 30–60 volts and hold currents of the order of a few milliamperes have been fabricated on 2 ohm cm. p-type germanium by allo...

Study of the Effects of Fast Neutrons on Silicon Controlled Rectifiers

Medium power silicon controlled rectifiers have been exposed to a maximum integrated fastneutron flux of 4 x 1013 nvt. An increase in the current required to turn on thie controlled rectifier and an increase in the break-over voltage were observed after irradiation. The saturation voltage increased as a result of irradiation, exceeding 200 volts at an integrated fast neutron flux of 4 x 1013 nvt. These changes are attributed to a decrease of the minority carrier lifetime as reflected by a decrease in alpha.

Switching mechanism in the n-p-n-p silicon controlled rectifier

The OFF state current-voltage characteristics of a two-terminal n-p-n-p silicon controlled rectifier are predicted by considering one-dimensional diffusion of minority carriers in the bulk regions and recombination and generation of carriers in the junction space-charge regions. It is concluded that the temperature dependence of the breakover voltage is strongly dependent on the lifetimes in the space-charge regions of the junctions. Evidence is shown that the carrier lifetime in the space-charge region of an alloyed junction may be less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> seconds even though the lifetime in the bulk is of the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> seconds. The effect of gate current on the device characteristic and gated turn-off are treated in a very approximate manner.

A high voltage, high speed, three terminal P-N-P-N switch

The design of high voltage, high speed, three terminal silicon P v PN switches for high pulse current applications is discussed. The resistivity of the v region and the minimum base widths are determined by the minimum breakover voltage requirement. The dependence of the delay and turn times and trigger requirements the two base widths is then analyzed. It is pointed out that the breakover voltage, speed, and peak current requirement in combination with the desire for a low on drop necessitates stringent control of the resistivity of the v material during processing. The emitter area and emitter contact sheet resistance are determined by the peak current requirement. Other design features of the device are also discussed. Representative values of the device parameters are given for various designs. In typical applications, the devices are capable of switching from 500 volts to 50 amperes with turn-on times of .05 µsec.

The Electrical Characteristics of Silicon P-N-P-N Triodes

An investigation is made of the electrical characteristics of three-terminal silicon p-n-p-n structures, where electrical contact is made to both outer (emitter) regions and to one of the inner (base) regions. When the base current Ib is zero, the V-I characteristic naturally is identical to the two-terminal case, i.e., ranges of high and low impedance separated by a region of differential negative resistance. Base current supplied from an independent, external circuit is found to decrease the breakover (peak) voltage and to decrease the turn-off current, i.e., the current at which the device enters the low impedance state. In fact, the p-n-p-n triode is found to exhibit switching properties closely analogous to the conventional thyratron. As an extension of earlier work, a general analysis of four-region structures is presented and is applied specifically to the p-n-p-n triode. Much of the detailed behavior of the device can be explained in terms of this analysis, and theoretical curves are given which are in good agreement with the experimental results.