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US 11,309,444 B1Granted
Microstructure enhanced absorption photosensitive devices
AssigneeW&W Sens Devices, Inc.
InventorsShih-Yuan Wang, Shih-Ping Wang
Life of this patent
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Abstract
Techniques for enhancing the absorption of photons in semiconductors with the use of microstructures are described. The microstructures, such as pillars and/or holes, effectively increase the effective absorption length resulting in a greater absorption of the photons. Using microstructures for absorption enhancement for silicon photodiodes and silicon avalanche photodiodes can result in bandwidths in excess of 10 Gb/s at photons with wavelengths of 850 nm, and with quantum efficiencies of approximately 90% or more.
Claims30
A device converting light photons to electrons, comprising:
- a silicon (Si) substrate and a laterally extending array of pillars formed therein that are elongated in up-down directions;
- wherein each of a plurality of the pillars in the array:
- has a rectangular laterally extending cross-section;
- comprises an undoped or low-doped Si absorption region, an upper doped Si region over the Si absorption region, and a lower doped Si region under the Si absorption region;
- has one or more dielectric-filled, pyramid-shaped, in-pillar holes extending down into the pillar from a top surface of said upper doped Si region of the pillar;
- has a top electrical contact electrically coupled with said upper doped Si region of the pillar;
- and
- has a bottom electrical contact electrically coupled with the lower doped Si region of the pillar;
- wherein said top and bottom electrical contacts are configured to provide reverse-bias from an external source to said pillar for operation of said device in a photodetector mode to convert light photons incident on said pillar to electrons;
- pillar-separating regions filled with dielectric that surround and laterally separate at least portions of said pillars from each other;
- a dielectric region under said Si substrate;
- wherein said pillars:
- are laterally spaced from each other, center to center, by 100-2,000 nanometers;
- and
- have up-down lengths of said absorption Si regions in the range of 100-5000 nanometers;
- wherein said pillars, in-pillar holes, and pillar-separating regions:
- increase photon absorption of said device by a factor of 1.1 or more at infrared wavelength of incident light compared to a like device lacking said one or more in-pillar holes;
- and
- facilitate operation of said device with infrared incident light;
- and
- wherein said device is CMOS compatible for mass production using CMOS foundries.
18 more elements
A device converting light photons to electrons, comprising:
- a silicon (Si) substrate and a laterally extending array of pillars formed therein that are elongated in up-down directions;
- wherein each of a plurality of the pillars in the array:
- comprises an undoped or low-doped Si absorption region, an upper doped Si region over the Si absorption region, and a lower doped Si region under the Si absorption region;
- has one or more dielectric-filled, in-pillar holes extending down into the pillar from a top surface of said upper doped Si region of the pillar;
- has a top electrical contact electrically coupled with said upper doped Si region of the pillar;
- and
- has a bottom electrical contact electrically coupled with the lower doped Si region of the pillar;
- wherein said top and bottom electrical contacts are configured to provide reverse-bias from an external source to said pillar for operation of said device in a photodetector mode to convert light photons incident on said pillar to electrons;
- pillar-separating regions filled with dielectric that surround and laterally separate at least portions of said pillars from each other;
- a dielectric region under said Si substrate;
- wherein said pillars:
- are laterally spaced from each other, center to center, by 100-2,000 nanometers;
- and
- have up-down lengths of said absorption Si regions in the range of 100-5000 nanometers;
- wherein said pillars, in-pillar holes, and pillar-separating regions:
- increase photon absorption of said device by a factor of 1.1 or more at infrared wavelength of incident light compared to a like device lacking said one or more in-pillar holes;
- and
- facilitate operation of said device with infrared incident light.
15 more elements
A device converting light photons to electrons, comprising:
- a silicon (Si) substrate and a laterally extending array of pillars formed therein that are elongated in up-down directions;
- wherein each of a plurality of the pillars in the array:
- has a rectangular laterally extending cross-section;
- comprises an undoped or low-doped Si absorption region, an upper doped Si region over the Si absorption region, and a lower doped Si region under the Si absorption region;
- has one or more in-pillar holes that extend down into the pillar and at least one is elongated in lateral cross-section;
- has a top electrical contact electrically coupled with said upper doped Si region of the pillar;
- and
- has a bottom electrical contact electrically coupled with the lower doped Si region;
- wherein said top and bottom electrical contacts are configured to provide reverse-bias from an external source to said pillar for operation of said device in a photodetector mode to convert light photons incident on said pillar to electrons;
- pillar-separating regions filled with dielectric that surround and laterally separate at least portions of said pillars from each other;
- a dielectric region under said Si substrate;
- wherein said pillars:
- have up-down lengths of said absorption Si regions in the range of 100-5000 nanometers;
- wherein said pillars, in-pillar holes, and pillar-separating regions:
- increase photon absorption of said device by a factor of 1.1 or more at infrared wavelength of incident light compared to a like device lacking said one or more in-pillar holes;
- and
- facilitate operation of said device with infrared incident light;
- and
- wherein said device is CMOS compatible for mass production using CMOS foundries.
16 more elements
A device converting light photons to electrons, comprising:
- a silicon (Si) substrate and a laterally extending array of pillars formed therein that are elongated in up-down directions;
- wherein each of a plurality of the pillars in the array:
- comprises an undoped or low-doped Si absorption region, an upper doped Si region over the Si absorption region, and a lower doped Si region under the Si absorption region;
- has one or more dielectric-filled, in-pillar holes extending down into the pillar from a top surface of said upper doped Si region of the pillar;
- has a top electrical contact electrically coupled with said upper doped Si region of the pillar;
- and
- has a bottom electrical contact electrically coupled with the lower doped Si region of the pillar;
- wherein said top and bottom electrical contacts are configured to provide reverse-bias from an external source to said pillar for operation of said device in a photodetector mode to convert light photons incident on said pillar to electrons;
- pillar-separating regions filled with dielectric that surround and laterally separate at least portions of said pillars from each other;
- a dielectric region under said Si substrate;
- wherein said pillars:
- have laterally dimensions ranging from 10 to 5000 nanometers and adjacent pillars are spaced from touch to 5,000 nm separation;
- and
- have up-down lengths of said absorption Si regions in the range of 100-5000 nanometers;
- wherein said pillars, in-pillar holes, and pillar-separating regions:
- increase photon absorption of said device by a factor of 1.1 or more at infrared wavelength of incident light compared to a like device lacking said one or more in-pillar holes;
- and
- facilitate operation of said device with infrared incident light.
15 more elements
Dependencies are inferred from the claim text.