Multi spectral sensor
A light sensor having a light conversion element between first and second electrodes is disclosed. The light conversion element includes a body of semiconductor material having first and second surfaces. The body of semiconductor material is of a first conductivity type and has doping elements in a concentration gradient that creates a first electrostatic field having a magnitude that varies monotonically from the first surface to the second surface. A bias circuit applies a variable potential between the first and second electrodes to create a second electrostatic field having a direction opposite to that of the first electrostatic field and a magnitude determined by the potential. One of the electrodes is transparent to light in a predetermined band of wavelengths. The body of semiconductor material can include an epitaxial body having a monotonically increasing concentration of a doping element as a function of the distance from one the surfaces.
1. A method for generating an output image of a scene comprising:
causing light from said scene to be focused on a sensor comprising a plurality of pixels, each pixel comprising a variable depletion region that collects charge generated by light from said scene that is focused on said pixel, said variable depletion region comprising a light conversion region having an extent determined by a wavelength control signal;
measuring charge collected by each pixel for a first value of said wavelength control signal to form a first image;
measuring charge collected by each pixel for a second value of said wavelength control signal to form a second image; and
combining said first and second images to generate said output image.
2. The method of claim 1 wherein each pixel comprises a light conversion element comprising a body of semiconductor material having first and second surfaces, said body of semiconductor material comprising a depletion zone having a boundary that is determined by said wavelength control signal;
a first electrode and a second electrode, said body of semiconductor material lying between said first and second electrodes;
a bias circuit that applies said wavelength control signal to first electrode; and
a charge collection circuit for collecting charges created when photons convert in said depletion region.
3. A method for generating an output image of a scene comprising:
causing light from said scene to be focused on a sensor comprising a plurality of pixels, each pixel comprising a variable depletion region that collects charge generated by light from said scene that is focused on said pixel, said variable depletion region comprising a light conversion region having an extent determined by a wavelength control signal; and
measuring charge collected by each pixel for a first value of said wavelength control signal to form a first image;
wherein each pixel comprises a light conversion element comprising a body of semiconductor material having first and second surfaces, said body of semiconductor material comprising a depletion zone having a boundary that is determined by said wavelength control signal;
a first electrode and a second electrode, said body of semiconductor material lying between said first and second electrodes;
a bias circuit that applies said wavelength control signal to first electrode; and
a charge collection circuit for collecting charges created when photons convert in said depletion region,
wherein said body of semiconductor material comprises a doping gradient that generates a static electric field in said body of semiconductor material and wherein said bias circuit creates a variable electric field having a direction opposite to that of said static electric field when said bias circuit applies said wavelength control signal to said first electrode.
4. The method of claim 3 wherein one of said static electric field and said variable electric field comprises an electric field having a magnitude that varies monotonically from said first surface to said second surface.