Claims
- 1. A photodetector, comprising:
a p-type region; a first n-type region forming a first pn junction with said p-type region, said first n-type region having a first layout area; a second n-type region, separated from said first n-type region, forming a second pn junction with said p-type region, said second n-type region having a second layout area that is greater than said first layout area; a light blocking material covering said first n-type region; and a current booster; wherein carriers are produced in said p-type region when light is incident on said second n-type region, a portion of said carriers being quickly captured by said second n-type region, a remaining portion of said carriers being slow carriers that wander around in said p-type region prior to being captured, a first portion of said slow carriers eventually being captured by said first n-type region, and a second portion of said slow carriers eventually being captured by said second n-type region, said first pn junction generating a first current resulting from said first portion of said slow carriers, and said second pn junction generating a second current resulting from both said quickly captured portion of said carriers and said second portion of said slow carriers; and wherein said current booster is adapted to boost said first current so that said first current is substantially equal to a portion of said second current that is due to said second portion of said slow carriers.
- 2. The photodetector of claim 1, further comprising a combiner adapted to subtract said first current from said second current to produce a difference signal having a fast response, said difference signal being an output of the photodetector.
- 3. The photodetector of claim 1, further comprising:
a first current-to-voltage converter that converts said first current to a first voltage; a second current-to-voltage converter that converts said second current to a second voltage; and a combiner to subtract said first voltage from said second voltage to produce a difference signal having a fast response, said difference signal being an output of the photodetector.
- 4. The photodetector of claim 1, wherein:
said first n-type region and said second n-type region are each n+ regions that are heavily doped; and said p-type region is a p− epi region that is lightly doped.
- 5. The photodetector of claim 1, wherein each of said first and second pn junctions are reverse biased.
- 6. A photodetector, comprising:
a p-type region; a plurality of n-type regions each forming a separate pn junction with said p-type region, each of said pn junctions being reverse biased; a first portion of said n-type regions being covered, electrically connected to one another, and collectively having a covered layout area; a second portion of said n-type regions being uncovered, electrically connected to one another, and collectively having an uncovered layout area that is greater than said covered layout area; wherein when light is incident on said uncovered second portion of said n-type regions, a first current is produced based on carriers collected by said covered first portion of said n-type regions, and a second current is produces based on carriers collected by said uncovered second portion of said n-type regions; and a means for boosting said first current to compensate for said uncovered layout area being greater than said covered layout area, prior to a current or voltage corresponding to said first current being subtracted from a current or voltage corresponding to said second current.
- 7. The photodetector of claim 6, further comprising a combiner adapted to subtract said first current from said second current to produce a difference signal having a fast response, said difference signal being an output of the photodetector.
- 8. The photodetector of claim 6, further comprising:
a first current-to-voltage converter that converts said first current to a first voltage; a second current-to-voltage converter that converts said second current to a second voltage; and a combiner to subtract said first voltage from said second voltage to produce a difference signal having a fast response, said difference signal being an output of the photodetector.
- 9. The photodetector of claim 6, wherein:
said n-type regions are each n+ regions that are heavily doped; and said p-type region is a p− epi region that is lightly doped.
- 10. The photodetector of claim 6, wherein said means for adjusting is adapted to adjust at least one of said first and second currents such that a portion of each of said currents due to said slow carriers is substantially equal.
- 11. The photodetector of claim 6, wherein:
said second portion of said n-type regions that are uncovered includes a plurality of separate generally hexagon shaped n-type regions that are electrically connected to one another; and said covered first portion of said n-type regions generally surrounds said plurality of hexagon shaped n-type regions, forming a generally honey-comb shape.
- 12. A photodetector, comprising:
a p-type region; a plurality of n-type regions each forming a separate pn junction with said p-type region; a first portion of said n-type regions being covered and collectively having a covered layout area; and a second portion of said n-type regions being uncovered and collectively having an uncovered layout area that is greater than said covered layout area, wherein said uncovered second portion of said n-type regions includes a plurality of separate generally hexagon shaped n-type regions that are electrically connected to one another.
- 13. The photodetector of claim 12, wherein said covered first portion of said n-type regions generally surrounds said plurality of hexagon shaped n-type regions.
- 14. The photodetector of claim 13, wherein said covered first portion of said n-type regions has a generally honey-comb shape.
- 15. The photodetector of claim 12, wherein:
when each of said pn junctions are reverse biased and light is incident on said uncovered second portion of said n-type regions, a first current is produced based on carriers collected by said covered first portion of said n-type regions, and a second current is produces based on carriers collected by said uncovered second portion of said n-type regions; the photodetector further comprising:
a means for adjusting at least one of said first and second currents to compensate for said uncovered layout area being greater than said covered layout area, prior to a current or voltage corresponding to said first current being subtracted from a current or voltage corresponding to said second current.
- 16. The photodetector of claim 12, wherein:
said n-type regions are each n+ regions that are heavily doped; and said p-type region is a p− epi region that is lightly doped.
- 17. The photodetector of claim 16, wherein said means for adjusting is adapted to adjust at least one of said first and second currents such that a portion of each of said currents due to slow carriers is substantially equal.
- 18. The photodetector of claim 12, wherein, when light is incident on said uncovered second portion of said n-type regions, a first current is produced based on carriers collected by said covered first portion of said n-type regions, and a second current is produces based on carriers collected by said uncovered second portion of said n-type regions, the photodetector further comprising:
a first current-to-voltage converter that converts said first current to a first voltage; a second current-to-voltage converter that converts said second current to a second voltage; and a means for adjusting at least one of said first and second voltages to compensate for said uncovered layout area being greater than said covered layout area, prior said first voltage being subtracted from said second voltage.
- 19. The photodetector of claim 18, wherein said means for adjusting is adapted to adjust at least one of said first and second voltages such that a portion of each of said voltages due to slow carriers is substantially equal.
- 20. A method for providing a photodetector having a fast response, comprising:
(a) providing a first conductivity type semiconductor material; (b) providing a plurality of regions of a second conductivity type semiconductor material, each of said plurality of regions forming a pn junction with said first conductivity type material, a first portion of said regions being covered and collectively having a covered layout area, a second portion of said regions being uncovered and collectively having an uncovered layout area, said uncovered layout area being greater than said covered layout area; (c) reverse biasing each pn junction; (d) exposing said layout areas to incident light to thereby produce a first current based on carriers collected by said covered first portion of said regions, and a second current based on carriers collected by said uncovered portion of said regions; (e) boosting said first current to compensate for said uncovered layout area being greater than said covered layout area; and (f) subtracting a current or voltage corresponding to said first current from a current or voltage corresponding to said second current, to produce a current or voltage difference signal having a fast response.
- 21. The method of claim 20, wherein:
said first conductivity type semiconductor material comprises a p-type semiconductor material; and said second conductivity type semiconductor material comprises an n-type semiconductor material.
- 22. The method of claim 20, wherein:
said first conductivity type semiconductor material comprises an n-type semiconductor material; and said second conductivity type semiconductor material comprises a p-type semiconductor material.
- 23. The method of claim 20, wherein step (e) comprises adjusting at least one of said first and second currents so that said first current is substantially equal to a portion of said second current that is due to slow carriers.
- 24. A method for providing a photodetector having a fast response, comprising:
(a) providing a first conductivity type semiconductor material; (b) providing a plurality of regions of a second conductivity type semiconductor material, each of said plurality of regions forming a pn junction with said first conductivity type material, a first portion of said regions being covered and collectively having a covered layout area, a second portion of said regions being uncovered and collectively having a uncovered layout area, said uncovered layout area being greater than said covered layout area; (c) reverse biasing each pn junction; (d) exposing said covered and uncovered layout areas to incident light to thereby produce a first current based on carriers collected by said covered first portion of said regions, and a second current based on carriers collected by said uncovered portion of said regions; (e) converting said first current to a first voltage, and said second current to a second voltage; (f) increasing the first voltage to compensate for said uncovered layout area being greater than said covered layout area; and (g) subtracting said first voltage from said second voltage to produce a voltage difference signal having a fast response.
- 25. The method of claim 24, wherein:
said first conductivity type semiconductor material comprises a p-type semiconductor material; and said second conductivity type semiconductor material comprises an n-type semiconductor material.
- 26. The method of claim 24, wherein:
said first conductivity type semiconductor material comprises an n-type semiconductor material; and said second conductivity type semiconductor material comprises a p-type semiconductor material.
- 27. The method of claim 24, wherein step (e) comprises adjusting said first voltage so that said first voltage is substantially equal to a portion of said second voltage that is due to slow carriers.
- 28. A photodetector, comprising:
a first conductivity type lightly doped semiconductor material; one or more heavily doped regions of semiconductor material of a second conductivity type, each forming a pn junction with said first conductivity type lightly doped semiconductor material, said one or more regions collectively having a first layout area and producing a first current; one or more further heavily doped regions of semiconductor material of said second conductivity type each forming a pn junction with said first conductivity type lightly doped semiconductor material, said one or more further regions collectively having a second layout area and producing a second current, said first layout area being greater than said second layout area; a light blocking material covering said one or more further regions; and a means for boosting said first current to compensate for said first layout area being greater than said second layout area, prior to a current or voltage corresponding to said first current being subtracted from a current or voltage corresponding to said second current.
- 29. The photodetector of claim 28, wherein:
said first conductivity type semiconductor material is a p-type material; and said second conductivity type semiconductor material is an n-type material.
- 30. The photodetector of claim 29, wherein:
said first conductivity type semiconductor material is an n-type material; and said second conductivity type semiconductor material is an p-type material.
- 31. A photodetector, comprising:
a first conductivity type semiconductor material; a plurality of generally hexagonal regions of semiconductor material of a second conductivity type, each forming a pn junction with said first conductivity type semiconductor material, said plurality of regions collectively having a first layout area; one or more further regions of semiconductor material of said second conductivity type each forming a pn junction with said first conductivity type semiconductor material, said further regions collectively having a second layout area; and a light blocking material covering said one or more further regions; wherein each of said first layout area and said second layout area are generally symmetrical in both X and Y directions.
- 32. The photodetector of claim 31, wherein said one or more further regions has a generally honeycomb shape.
- 33. The photodetector of claim 31, wherein said one or more further regions comprise a single generally honeycomb shaped region that generally surrounds said generally hexagonal regions.
PRIORITY CLAIM
[0001] This application claims priority to U.S. patent application Ser. No. 60/424,749, entitled “Improved Spatially Modulated Photodetectors,” filed Nov. 7, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60424749 |
Nov 2002 |
US |