Optically controllable static induction thyristor device

An optically controllable semiconductor device, comprising at least one optically controllable unit for varying the conduction of a controllable current path connected in series between first and second output terminals of said semiconductor device, said optically controllable unit comprising:

• a negative bias voltage source having first and second terminals with said first terminal being at a lower potential than said second terminal;
• first and second photo sensitive elements each having first and second terminals and each having a conduction path between said first and second terminals the conductance of which varies in accordance with optical irradiation of each respective photo sensitive element, said first terminal of said first photo sensitive element being connected to said first terminal of said negative bias voltage source, said second terminal of said first photo sensitive element being connected to a first connection point for providing an optically controllable bias voltage, said second terminal of said negative bias voltage source being connected to a second connection point, said second photo sensitive element having its conduction path coupled between said first and second connection points;
• an optical source for providing a first irradiation and a second irradiation complementary to said first irradiation for irradiating said first and second photosensitive elements;
• and
• at least one static induction thyristor, said thyristor including a channel region having a first region of relatively low impurity concentration and having a plurality of channel region portions, said channel region having first and second major surfaces, anode means comprising at least one highly-doped semiconductor anode region formed adjacent said first major surface and being of a first conductivity type, cathode means comprising a plurality of highly-doped cathode regions formed adjacent said second major surface and electrically connected to said second connection point, said anode, cathode and channel regions being disposed relative to one another in a semiconductor body so as to define respective current paths between said at least one anode region and different ones of said cathode regions through respective channel region portions, said respective current paths comprising said controllable current path, said static induction thyristor further including gate means responsive to said optically controlled bias voltage for generating depletion regions extending into said channel region portions to control current flow through said respective current paths, said gate means comprising a plurality of gate portions of said first conductivity type and having an impurity concentration throughout each gate portion of at least 1.times.10.sup.19 cm.sup.-3, said gate portions being electrically connected to one another and to said first connection point, said first and second photosensitive elements receiving said first and second complementary irradiations, respectively, one for triggering and the other for quenching said static induction thyristor, said static induction thyristor turning off in response to a reverse bias between said gate portions and said cathode regions when said first photosensitive element provides said negative bias voltage to said gate means.

An optically controllable semiconductor device, comprising at least one optically controllable unit for varying the conduction of a controllable current path connected in series between first and second output terminals of said semiconductor device, said optically controllable unit comprising:

• a negative bias voltage source having first and second terminals with said first terminal being at a lower potential than said second terminal;
• a photo sensitive element having first and second terminals and having a conduction path between said first and second terminals which varies in accordance with optical irradiation of said photo sensitive element, said first terminal of said photo sensitive element being connected to said first terminal of said negative bias voltage source and said second terminal of said photo sensitive element providing an optically controlled bias voltage, said photo sensitive element having a predetermined static capacitance;
• an optical source for irradiating said photo sensitive element;
• and
• at least one static induction thyristor, said thyristor including a channel region (12) having a first region of relatively low impurity concentration and having a plurality of channel region portions within said first region, said channel region having first and second major surfaces, anode means comprising at least one highly-doped semiconductor anode region (11) formed adjacent said first major surface and being of a first conductivity type, cathode means comprising a plurality of highly-doped cathode region (13) formed adjacent said second major surface and electrically connected to said second terminal of said negative bias voltage source, said anode, cathode and channel regions being disposed relative to one another in a semiconductor body so as to define respective current paths between said anode region and different ones of said cathode regions through respective channel region portions, said respective current paths comprising said controllable current paths, said static induction thyristor further including gate means responsive to said optically controlled bias voltage for generating depletion regions extending into said channel region portions to control current flow through said current paths, said gate means comprising a plurality of gate portions (14) of said first conductivity type and having an impurity concentration throughout each gate portion of at least 1.times.10.sup.19 cm.sup.-3, said gate portions being electrically connected to one another and to said second terminal of said photo sensitive element, said static induction thyristor turning off in response to a reverse bias between said gate portions and said cathode regions when said photosensitive element provides said negative bias voltage to said gate means upon irradiation of said photosensitive element for quenching said static induction thyristor, said static induction thyristor having a gate-source capacitance which is sufficiently larger than the static capacitance of said photo sensitive element that substantially no voltage is applied to said gate of said static induction thyristor through said photo sensitive element when said irradiation is terminated, said anode means comprising a plurality of said anode regions and at least one further highly-doped region of a conductivity type different from said first conductivity type separating said plurality of anode regions, said plurality of anode regions each being disposed at said first major surface at a position opposite one of said cathode regions, and said further semiconductor region being formed at said first major surface at a position opposite said gate means.

An optically controllable semiconductor device, comprising a plurality of optically controllable units each for varying the conduction of a controllable current path connected in series between first and second output terminals of said semiconductor device, said optically controllable units having their respective controllable current paths coupled in series with one another between said first and second output terminals of said device to form a compound optically controllable unit, each said optically controllable unit comprising:

• a negative bias voltage source having first and second terminals with said first terminal being at a lower potential than said second terminal;
• first and second photo sensitive elements each having first and second terminals and each having a conduction path between said first and second terminals the conductance of which varies in accordance with optical irradiation of each respective photo sensitive element, said first terminal of said first photo sensitive element being connected to said first terminal of said negative bias voltage source, said second terminal of said first photo sensitive element being connected to a first connection point for providing an optically controllable bias voltage, said second terminal of said negative bias voltage source being connected to a second connection point, said second photo sensitive element having its conduction path coupled between said first and second connection points;
• an optical source for providing a first irradiation and a second irradiation complementary to said first irradiation for irradiating said first and second photosensitive elements;
• and
• at least one static induction thyristor, said thyristor including:
• a channel region having a first region of relatively low impurity concentration and having a plurality of channel region portions, said channel region having first and second major surfaces;
• anode means comprising a plurality of highly-doped semiconductor anode regions formed adjacent said first major surface and being of a first conductivity type and at least one further highly-doped semiconductor region of a conductivity type opposite said first conductivity type separating said plurality of anode regions, said anode means including a thin semiconductor layer (16) of said opposite conductivity type sandwiched between said anode regions and said channel region, said thin layer having an impurity concentration higher than that of said channel region and having a thickness much smaller than that of said channel region;
• cathode means comprising a plurality of highly-doped cathode regions formed adjacent said second major surface and electrically connected to said second connection point, said anode, cathode and channel regions being disposed relative to one another in a semiconductor body with said anode regions each being disposed at a position opposite one of said cathode regions and said further semiconductor region being formed opposite said gate means so as to define respective current paths between respective anode regions and different ones of said cathode regions through respective channel region portions, said respective current paths comprising said controllable current paths;
• said static induction thyristor further including gate means responsive to said optically controlled bias voltage for generating depletion regions extending into said channel region portions to control current flow through said current paths, said gate means comprising a plurality of gate portions of said first conductivity type and having an impurity concentration throughout each gate portion of at least 1.times.10.sup.19 cm.sup.-3, said gate portions being electrically connected to one another and to said first connection point, said first and second photosensitive elements receiving said first and second complementary irradiations, respectively, one for triggering and the other for quenching said static induction thyristor, said static induction thyristor turning off in response to a reverse bias between said gate portions and said cathode regions when said first photosensitive element provides said negative bias voltage to said gate means.

An optically controllable semiconductor device, comprising at least one optically controllable unit for varying the conduction of a controllable current path connected in series between first and second output terminals of said semiconductor device, said optically controllable unit comprising:

• a negative bias voltage source having first and second terminals with said first terminal being at a lower potential than said second terminal;
• a photo sensitive element having first and second terminals and having a conduction path between said first and second terminals which varies in accordance with optical irradiation of said photo sensitive element, said first terminal of said photo sensitive element being connected to said first terminal of said negative bias voltage source and said second terminal of said photo sensitive element providing an optically controlled bias voltage;
• an optical source for irradiating said photo sensitive element;
• at least one static induction thyristor, said thyristor including a channel region (12) having a first region of relatively low impurity concentration and having a plurality of channel region portions within said first region, said channel region having first and second major surfaces, anode means comprising at least one highly-doped semiconductor anode region (11) formed adjacent said first major surface and being of a first conductivity type, cathode means comprising a plurality of highly-doped cathode regions (13) formed adjacent said second major surface and electrically connected to said second terminal of said negative bias voltage source, said anode, cathode and channel regions being disposed relative to one another in a semiconductor body so as to define respective current paths between said anode region and different ones of said cathode regions through respective channel region portions, said respective current paths comprising said controllable current paths, said static induction thyristor further including gate means responsive to said optically controlled bias voltage for generating depletion regions extending into said channel region portions to control current flow through said current paths, said gate means comprising a plurality of gate portions (14) of said first conductivity type and having an impurity concentration throughout each gate portion of at least 1.times.10.sup.19 cm.sup.-3, said gate portions being electrically connected to one another and to said second terminal of said photo sensitive element, said static induction thyristor turning off in response to a reverse bias between said gate portions and said cathode regions when said photosensitive element provides said negative bias voltage to said gate means upon irradiation of said photosensitive element for quenching said static induction thyristor;
• and
• another photosensitive element connected between said gate means and said cathode means of said static induction thyristor, said first-mentioned photosensitive element and said another photosensitive element receiving complementary optical irradiation, one for triggering and the other for quenching said static induction thyristor.