General Electric Company

Electric Power Research Institute Incorporated

B Jayant Baliga

Victor A Temple

Douglas E Houston

Surinder Krishna

A field controlled thyristor having its base doped more lightly near the gate than near the anode achieves a low forward voltage drop, high blocking gain, and fast switching speed at any given forward blocking voltage rating. Although the high resistivity region around the gate area allows the device to pinch off anode current flow at zero gate bias due to the gate junction inherent potential, a small forward gate voltage can trigger the device into conduction. The high resistivity of the channel area between gates provides DC blocking gains greater than 60. The device can be fabricated using conventional planar processing techniques.

Asymmetrical field controlled thyristor

A field-controlled bipolar transistor characterized by a bidirectional voltage blocking capability between the collector and emitter electrodes is described as comprising a semiconductor substrate with base, emitter and collector regions formed in the semiconductor substrate with the base region of one conductivity type and the emitter and collector regions of opposite conductivity type. A gate region, also of opposite conductivity type, is formed in the substrate and positioned with respect to the emitter and collector regions so that when the junction formed between the gate region and the substrate is reverse-biased, a depletion region forms which pinches off current flow between the emitter and collector regions thereby providing a transistor that is capable of blocking high voltages in both forward and reverse directions while having normal bipolar transistor characteristics in the forward direction.

Field-controlled bipolar transistor

A thyristor is protected against voltage breakover turn-on failure by selective control of the minority charge carrier lifetime in the base region and in the gate region to establish a predictable location of the voltage breakover turn-on in the gate region. Carrier lifetime modification in the selected gate region is achieved by shielding the gate region during electron irradiation of the high-lifetime silicon substrate to protect against lifetime-killing radiation defect centers, by annealling the gate region after electron irradiation to a temperature threshold known to eliminate the radiation-induced defects, or by introducing lifetime killing defects, such as gold or platinum, external to the gate region, typically by selective diffusion or localized ion implantation. As a result, a locally higher gate sub-transistor gain thyristor is attained, so that the turn-on criterion, the unity product of the base transport factor and the avalanche multiplication factor, is established at a lower voltage in the gate region than elsewhere in the thyristor device.

Self-protection against breakover turn-on failure in thyristors through

An electric field-controlled thyristor having improved voltage blocking characteristics comprises a semiconductor substrate with a cathode region in one major surface and interdigitated anode and gate regions in the other major surface. The thyristor includes a single high voltage junction which is capable of blocking voltages of either positive or negative polarity by the application of a control voltage, which is a fraction of the blocking voltage, between the anode and gate regions.

Electric field-controlled semiconductor device

Geometrical design criteria are disclosed for a Gate Modulated BiPolar Transistor, or GAMBIT, which is a three terminal variable negative resistance device. The GAMBIT is a planar, interdigited, integrated device whose electrical characteristics show a voltage controlled negative resistance between two of its terminals. The magnitude of the negative resistance is controlled by the variation of the applied bias to the third terminal.

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Schenectady, NY, United States of America

B Jayant Baliga