Light-activated lateral thyristor and ac switch

Claim 2

A light activated lateral thyristor circuit comprising: a. a lateral thyristor formed in a semiconductor body of given impurity concentration having a major surface, said thyristor having a first impurity region of conductivity type opposite the given impurity concentration adjoining the major surface and forming a first PN junction with a shallow impurity concentration gradient less than about 1 X 1022 per cm4 with the given impurity concentration of the body, a second impurity region of conductivity type opposite the first impurity region adjoining the major surface, contained within the first impurity region and forming a second PN junction with the first impurity region, and a third impurity region of conductivity type opposite the given concentration adjoining the major surface, spaced from the first impurity region and forming a third PN junction with the given impurity concentration of the body and a fourth residual impurity region adjoining the major surface between the first and third impurity region; b. a power source capable of applying a voltage potential ohmically between the second and third impurity regions; and c. a light radiation source capable of illuminating said major surface at at least portions of the first and fourth impurity regions to gate the thyristor as the voltage potential of the power source is applied.

Claim 3

A light activated thyristor circuit as set forth in claim 1 wherein: the first and fourth impurity regions of the lateral thyristor have surface impurity concentrations between about 2 X 1015 and 1 X 1018 per cm3.

Claim 4

A light activated thyristor circuit as set forth in claim 1 wherein: the first and fourth impurity regions of the lateral thyristor have surface widths substantially equalizing gRounded base current gains of the equivalent transistors of the thyristor.

Claim 5

A light activated lateral thyristor circuit as set forth in claim 1 wherein: the impurity concentration gradient of the first PN junction of the thyristor is less than 1 X 1020 per cm4.

Claim 6

A light activated ac switch circuit comprising: a. two lateral thyristors formed in a semi-conductor body of a given impurity concentration having a major surface, each said thyristor having a first impurity region of conductivity type opposite the given impurity concentration adjoining the major surface and forming a first PN junction with a shallow impurity concentration gradient less than about 1 X 1022 per cm4 with the given impurity concentration of the body, a second impurity region of conductivity type opposite the first impurity region adjoining the major surface, contained within the first impurity region and forming a second PN junction with the first impurity region, and a third impurity region of conductivity type opposite the given concentration adjoining the major surface, spaced from the first impurity region and forming a third PN junction with the given impurity concentration of the body and a fourth residual impurity region adjoining the major surface between the first and third impurity region; b. interconnecting contacts ohmically connecting the second impurity region of each thyristor with the third impurity region of the other thyristor; c. a power source capable of applying a voltage potential ohmically between the second and third impurity regions; and d. a light radiation source capable of illuminating said major surface at at least portions of the first and fourth impurity regions to gate the thyristor as the voltage potential of the power source is applied.

Claim 7

A light activated ac switch circuit comprising: a. two lateral thyristors formed in a semi-conductor body of a given impurity concentration having a major surface, each said thyristor having a first impurity region of conductivity type opposite the given impurity concentration adjoining the major surface and forming a first PN junction with a shallow impurity concentration gradient less than about 1 X 1022 per cm4 with the given impurity concentration of the body, a second impurity region of conductivity type opposite the first impurity region adjoining the major surface, contained within the first impurity region and forming a second PN junction with the first impurity region, and a third impurity region of conductivity type opposite the given concentration adjoining the major surface, spaced from the first impurity region and forming a third PN junction with the given impurity concentration of the body and a fourth residual impurity region adjoining the major surface between the first and third impurity region; b. interconnecting contacts ohmically connecting the second impurity region of each thyristor with the third impurity region of the other thyristor; c. a power source capable of applying a voltage potential ohmically between the second and third impurity regions; and d. a light radiation source capable of illuminating said major surface at at least portions of the first and fourth impurity regions to gate the thyristor as the voltage potential of the power source is applied.

Claim 8

A light activated ac switch circuit as set forth in claim 5 wherein: the first and fourth impurity regions of each lateral thyristor have surface impurity concentrations between about 2 X 1015 and 1 X 1018 per cm3.

Claim 9

A light activated ac switch circuit as set forth in claim 5 wherein: the first and fourth impurity regions of each lateral thyristor have surface widths substantially equalizing grounded base current gains of the equivalent transistors of the thyristor.

Claim 10

A light activated ac switch circuit as set forth in claim 5 wherein: the impurity concentration gradient of the first PN junction of each thyristor is less than 1 X 1020 per cm4.

Claim 11

A light activated ac switch circuit as set forth in claim 5 wherein: the interconnecting contacts are planar and partially overlay a dielectric layer adjoining the major surface of the semiconductor body.