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Methods and devices for improved charge management for three-dimensional and color sensing

  • US 7,352,454 B2
  • Filed: 02/06/2006
  • Issued: 04/01/2008
  • Est. Priority Date: 11/09/2000
  • Status: Expired due to Term
First Claim
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1. A CMOS-implementable semiconductor photodetector useable in a system that illuminates a target with optical energy having a modulated periodic waveform that includes a high frequency component, generated in response to signal provided by a clock generator, and that detects a fraction of said optical energy reflected by said target with at least one said semiconductor photodetector, said photodetector comprising:

  • a semiconductor substrate having a surface upon which said incoming optical energy can impinge onto an optical energy sensitive region, said surface defining an x-direction and a y-direction;

    at least a first elongate-shaped polysilicon gate disposed on said surface parallel to said y-direction, said first gate coupleable to a first bias clock signal, synchronously generated by said clock generator, that is high during a first bias regime to detect and collect charge generated by at least a fraction of said incoming optical energy;

    a first source region formed in said substrate adjacent a distal end of said first gate;

    at least a second elongate-shaped polysilicon gate disposed on said surface parallel to said first elongate-shaped gate and spaced-apart in said x-direction a distance substantially shorter than a length of either said gate, said second gate coupleable to a second bias clock signal synchronously generated by said clock generator;

    a second source region formed in said substrate adjacent a distal end of said second gate;

    wherein responsive to said first bias clock signal and said second bias clock signal, photoelectic charge generated in said substrate is moved in said x direction to become trapped beneath an elongate-shaped gate and is then moved in said y-direction to an adjacent source region for collection, charge movement in said y-direction being slower than charge movement in said x-direction, wherein modulation contrast of said photodetector is enhanced.

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