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US 2014/0197453 A1Published application
Image sensor with layers of direct band gap semiconductors having different band gap energies
AssigneeBroadcom Corporation
InventorIlya Blayvas
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Abstract
Embodiments of an exemplary image sensor structure of the present disclosure contains at least two different layers of band gap semiconductors, where each upper layer of the different layers has a different band gap than a lower layer. For such an image sensor structure, the upper layer has a greater band gap than any layer positioned below the upper layer including the lower layer.
Claims20
An image sensor structure comprising:
- at least two different layers of direct band gap semiconductors positioned in a stack, each upper layer of the different layers having a different band gap than a lower layer,
- wherein the upper layer has a greater band gap than any layer positioned below the upper layer including the lower layer,
- wherein the lower layer encounters light to be sensed after the light passes through the upper layer.
A method comprising:
- epitaxially growing a stack of three or more direct band gap photo-diodes with sequentially decreasing band gap from top to bottom, where the photo-diode engaging first with the incident light is the top photo-diode;
- forming one or more photo-sensitive elements within each of the photo-diodes based on electric conductivity increasing with generation of electron-hole pairs by absorption of photons with energy exceeding the band gap energy;
- and
- connecting circuitry enabling measuring and reading out of light energy within a controlled time interval, separately from each photo-diode corresponding to separate sub-band of a color spectrum, wherein each photo-sensitive element is connected to the circuitry.
1 more element
A color image sensor structure, comprising:
- a layered structure having selective absorption within pre-designed light bandwidths, the layer structure comprising:
- an upper layer of a first direct band gap semiconductor diode;
- a middle layer of a second direct band gap semiconductor diode;
- and
- a lower layer of a third direct band gap semiconductor diode, wherein a band gap energy of the upper layer is greater than a band gap energy of the middle layer which is greater than a band gap energy of the lower layer.
2 more elements
Dependencies are inferred from the claim text.