SEMICONDUCTOR VIDICON TARGET HAVING ELECTRONICALLY ALTERABLE LIGHT RESPONSE CHARACTERISTICS

• US 3,576,392 A
• Filed: 06/26/1968
• Issued: 04/27/1971
• Est. Priority Date: 06/26/1968
• Status: Expired due to Term

• Current Assignee: Steven R. Hofstein
• Original Assignee: Steven R. Hofstein
• Inventors: Hofstein, Steven R.
• Application Number:
  US04/740,350
• Time in Patent Office: 1,035 Days
• US Class Current: 348/331
• CPC Class Codes: H01J 29/455 formed on a silicon substrate
• CPC Class Codes: H01L 27/00 Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate details thereof H01L23/00, H01L29/00 - H10K10/00; assemblies consisting of a plurality of individual solid state devices H01L25/00
• CPC Class Codes: Y10S 148/12 Photocathodes-Cs coated and solar cell
• CPC Class Codes: Y10S 257/917 Plural dopants of same conductivity type in same region

Abstract

A silicon vidicon target comprises an N-type silicon wafer having one surface exposed to incident light, and a large number of discrete P-type regions diffused into the opposite wafer surface, which is scanned by an electron beam. A transparent electrode overlies a transparent insulator disposed on the illuminated wafer surface. The optical sensitivity and spectral response of the target are varied by applying a bias voltage between the transparent electrode and the N-type wafer.

Claims

2. Apparatus according to claim 1, further comprising a multiplicity of spaced opposite conductivity-type regions inset into said wafer from said one major surface, with a PN junction between each of said regions and the adjacent part of said wafer.

3. Apparatus according to claim 2, wherein said semiconductor comprises silicon.

4. Apparatus according to claim 3, wherein said recombination means comprises a minority carrier collecting region of said opposite conductivity-type inset into said wafer from said other major surface.

5. Apparatus according to claim 4, wherein at least a part of said collecting region underlies said transparent electrode.

6. Apparatus according to claim 3, wherein said recombination means comprises a metallic electrode on a limited part of said other major surface, said metallic electrode cooperating with said surface part to form a Schottky barrier at the interface therebetween.

7. Apparatus according to claim 6, wherein said metallic electrode comprises platinum silicide.

8. Apparatus according to claim 2, wherein said at least one region is of P-conductivity-type.

9. Apparatus according to claim 2, further comprising:

a source of potential difference; and

means, including said source and said transparent electrode, for establishing an electric field in a portion of said wafer adjacent said other major surface to deplete said portion of majority carriers, said field acting to impel minority carriers toward said other major surface.

10. Optical image conversion apparatus, comprising:

a semiconductor wafer of one conductivity type having a multiplicity of spaced opposite conductivity-type regions inset into said wafer from one major surface, with a PN junction between each of said regions and the adjacent part of said wafer;

a transparent insulating layer on the other major surface of the wafer;

minority carrier recombination means at said other major surface;

a transparent electrode on said transparent insulating layer;

a source of potential difference;

means, including said source and said transparent electrode, for establishing an electric field in a portion of said wafer adjacent said other major surface to deplete said portion of majority carriers, said field acting to impel minority carriers toward said other major surface;

scanning means, including an electron beam, for successively applying a given reverse bias to each of said PN junctions;

means responsive to fluctuations in the current carried by said electron beam to derive a signal representative of the light flux incident on said wafer; and

means, responsive to said signal, for varying said applied potential difference.

11. Apparatus according to claim 10, wherein said signal deriving means includes integrating means, and said signal indicates the time at which said flux reaches a predetermined value, said potential difference being varied at said time to substantially increase the Portion of said wafer depleted of majority carriers.

12. Optical image on conversion apparatus, comprising:

a semiconductor wafer of one conductivity type having a multiplicity of spaced opposite conductivity-type regions inset into said wafer from one major surface, with a PN junction between each of said regions and the adjacent part of said wafer;

a transparent insulating layer on the other major surface of the wafer;

minority carrier recombination means at said other major surface;

a transparent electrode on said transparent insulating layer;

a source of potential difference; and

means, including said source and said transparent electrode, for establishing an electric field in a portion of said wafer adjacent said other major surface to deplete said portion of majority carriers, said field acting to impel minority carriers toward said other major surface;

means for periodically varying said potential difference to vary the spectral response of said wafer to incident light;

scanning means, including an electron beam, for successively applying a given reverse bias to each of said PN junctions;

means for detecting fluctuations in the current carried by said electron beam; and

means, responsive to said detecting means and synchronous with said periodic varying means, for deriving a plurality of video signals representative of corresponding color components of any light incident on said wafer.

13. Optical image conversion apparatus, comprising:

a semiconductor wafer having a given major surface exposed to said image, said wafer comprising (i) a body of semiconductor material of one conductivity type, and (ii) at least one region of opposite conductivity-type semiconductor material forming a PN junction with said body, said region having a portion exposed at the other major surface of said wafer;

scanning means, including an electron beam for periodically establishing a predetermined reverse bias across said PN junction;

means, responsive to fluctuations in the current carried by said electron beam, for deriving a video signal representative of the intensity of said image integrated over said period; and

means including a control electrode capacitively coupled to said wafer and including also a minority carrier collecting region at said given major surface, for varying the response of said video signal to incident optical radiation.

14. Optical image conversion apparatus, comprising:

a semiconductor wafer having a given major surface exposed to said image, said wafer comprising (i) a body of semiconductor material of one conductivity type, and (ii) at least one region of opposite conductivity-type semiconductor material forming a PN junction with said body, said region having a portion exposed at the other major surface of said wafer;

scanning means, including an electron beam, for periodically establishing a predetermined reverse bias across said PN junction;

means, responsive to fluctuations in the current carried by said electron beam, for deriving a video signal representative of the intensity of said image integrated over said period;

means, including a control electrode capacitively coupled to said wafer, for varying the response of said video signal to incident optical radiation; and

automatic exposure control means, responsive to a control signal, for substantially reducing the sensitivity of said video signal to incident optical radiation, said scanning means and said video signal deriving means continuing to operate after said sensitivity reduction.

15. Apparatus according to claim 14, wherein said control means comprises (i) means for monotonically integrating said video signal, and (ii) threshold means for generating said control signal when the integrated video signal exceeds a predetermined value.

16. Optical image conversion apparatus, comprising:

a semiconductor wafer having a given major surface exposed to said image, saiD wafer comprising (i) a body of semiconductor material of one conductivity type, and (ii) at least one region of opposite conductivity-type semiconductor material forming a PN junction with said body, said region having a portion exposed at the other major surface of said wafer;

scanning means, including an electron beam, for periodically establishing a predetermined reverse bias across said PN junction;

means, responsive to fluctuations in the current carried by said electron beam, for deriving a video signal representative of the intensity of said image integrated over said period;

means, including a control electrode capacitively coupled to said wafer, for varying the response of said video signal to incident optical radiation;

means for applying a control signal to said electrode, said signal being capable of varying the sensitivity of said signal being capable of varying the sensitivity of said video signal to incident optical radiation, said sensitivity variation having a given dynamic range for optical radiation of wavelength shorter than a particular value; and

an optical filter for exposing said surface to only that optical radiation of a wavelength shorter than said particular value.

17. Apparatus according to claim 1, wherein said semiconductor comprises silicon.

18. Optical image conversion apparatus, comprising:

a target comprising a semiconductor wafer of one conductivity type having at least one region of opposite conductivity type adjacent one major surface of the wafer;

minority carrier recombination means at the wafer surface exposed to said optical image including a minority carrier collecting region; and

means, including a control electrode capacitively coupled to said surface, for varying the response of said target to incident optical radiation.

19. Apparatus according to claim 18, further comprising vacuum tube means for projecting an electron beam onto a major surface of said wafer.

20. Apparatus according to claim 19, further comprising means, including said electron beam, for deriving a signal representative of said optical radiation.