Controlling detection time in photodetectors

Patent metadata

Field	Value
Publication number	US-11973154-B2
Application number	US-202318159508-A
Country	US
Kind code	B2
Filing date	Jan 25, 2023
Priority date	Jan 29, 2018
Publication date	Apr 30, 2024
Grant date	Apr 30, 2024

Abstract

Example embodiments relate to controlling detection time in photodetectors. An example embodiment includes a device. The device includes a substrate. The device also includes a photodetector coupled to the substrate. The photodetector is arranged to detect light emitted from a light source that irradiates a top surface of the device. A depth of the substrate is at most 100 times a diffusion length of a minority carrier within the substrate so as to mitigate dark current arising from minority carriers photoexcited in the substrate based on the light emitted from the light source.

First claim

What is claimed is:

1. A device comprising:
a substrate; and
a photodetector coupled to the substrate,
wherein the photodetector is arranged to detect light emitted from a light source that irradiates a top surface of the device; and
an anti-reflective layer coupled to a second surface of the substrate,
wherein the anti-reflective layer is configured to couple light passing through the substrate to an exterior of the device, thereby preventing reflections within the substrate of the light emitted from the light source so as to reduce minority carrier photoexcitation in the substrate based on the light emitted from the light source, so as to mitigate dark current arising from minority carriers photoexcited in the substrate based on the light emitted from the light source.

2. The device of claim 1 , further comprising an additional photodetector coupled to the substrate,
wherein the additional photodetector is arranged to detect light emitted from the light source that irradiates the top surface of the device and is electrically connected in series with the photodetector.

3. The device of claim 1 , wherein the anti-reflective layer comprises a graded-index anti-reflective coating, a quarter-wave optical layer, a Bragg grating, a diffraction grating, or an index-matched, passive substrate.

4. A device comprising:
a substrate; and
a photodetector coupled to the substrate,
wherein the photodetector is arranged to detect light emitted from a light source that irradiates a top surface of the device,
wherein a second surface of the substrate is polished or planarized, thereby preventing reflections within the substrate of the light emitted from the light source so as to reduce minority carrier photoexcitation in the substrate based on the light emitted from the light source, thereby mitigating dark current arising from minority carriers photoexcited in the substrate based on the light emitted from the light source.

5. The device of claim 4 , further comprising an additional photodetector coupled to the substrate,
wherein the additional photodetector coupled to the substrate is arranged to detect light emitted from the light source that irradiates the top surface of the device and is electrically connected in series with the photodetector.

6. A device comprising:
a substrate;
a photodetector coupled to the substrate; and
a band-reject optical filter,
wherein the photodetector is arranged to detect light emitted from a light source that irradiates a top surface of the device,
wherein light from the light source that irradiates the top surface of the device is transmitted through the band-reject optical filter, and
wherein the band-reject optical filter is configured to reduce intensity of one or more wavelengths of the light emitted from the light source, so as to reduce minority carrier photoexcitation in the substrate based on the light emitted from the light source, thereby mitigating dark current arising from minority carriers photoexcited in the substrate based on the light emitted from the light source.

7. The device of claim 6 , further comprising an additional photodetector coupled to the substrate,
wherein the additional photodetector coupled to the substrate is arranged to detect light emitted from the light source that irradiates the top surface of the device and is electrically connected in series with the photodetector.

8. The device of claim 6 , further comprising a beam splitter, and wherein the beam splitter is configured to reduce intensity of one or more wavelengths of the light emitted from the light source.

9. The device of claim 8 , wherein the beam splitter comprises a half-silvered mirror.

10. The device of claim 6 , further comprising a neutral-density filter, and wherein the neutral-density filter is configured to reduce intensity of one or more wavelengths of the light emitted from the light source.

11. The device of claim 10 , wherein the neutral-density filter comprises a ND2 filter, a ND4 filter, a ND8 filter, a ND16 filter, a ND32 filter, a ND64 filter, a ND100 filter, a ND128 filter, a ND256 filter, a ND400 filter, a ND512 filter, a ND1024 filter, a ND2048 filter, a ND4096 filter, a ND6310 filter, a ND8192 filter, a ND10000 filter, or a ND100000 filter.

12. The device of claim 6 , wherein the band-reject optical filter was added to the device in post-processing.

13. The device of claim 6 , further comprising a protective layer to protect the photodetector from physical damage.

14. The device of claim 13 , wherein the band-reject optical filter overlays the protective layer.

15. The device of claim 13 , wherein the protective layer is sized such that it is approximately a quarter of a wavelength thick with respect to one or more wavelengths of the light emitted from the light source.

16. The device of claim 13 , wherein the protective layer comprises a material that is optically transparent with respect to one or more wavelengths of the light emitted from the light source.

17. The device of claim 16 , wherein the material that is optically transparent with respect to one or more wavelengths of the light emitted from the light source comprises SiO 2 .

18. A device comprising:
a substrate;
a photodetector coupled to the substrate; and
a non-linear optical absorber,
wherein the photodetector is arranged to detect light emitted from a light source that irradiates a top surface of the device,
wherein light from the light source that irradiates the top surface of the device is transmitted through the non-linear optical absorber, and
wherein the non-linear optical absorber is configured to reduce intensity of one or more wavelengths of the light emitted from the light source that are at or above a threshold power level, so as to reduce minority carrier photoexcitation in the substrate based on the light emitted from the light source, thereby mitigating dark current arising from minority carriers photoexcited in the substrate based on the light emitted from the light source.

19. The device of claim 18 , further comprising an additional photodetector coupled to the substrate,
wherein the additional photodetector coupled to the substrate is arranged to detect light emitted from the light source that irradiates the top surface of the device and is electrically connected in series with the photodetector.

20. The device of claim 18 , wherein the non-linear optical absorber is between 1 nm and 10 nm in thickness, between 10 nm and 100 nm in thickness, between 100 nm and 1 μm in thickness, between 1 μm and 10 μm in thickness, between 10 μm and 100 μm in thickness, between 100 μm and 1 mm in thickness, between 1 mm and 1 cm in thickness, or between 1 cm and 10 cm in thickness.

Assignees

• Waymo Llc

Inventors

• Onal Caner
• Verghese Simon
• Droz Pierre-Yves

Classifications

• H10F71/131

  Recrystallisation; Crystallization of amorphous or microcrystalline semiconductors · CPC title

• H10F71/00

  Manufacture or treatment of devices covered by this subclass (patterning processes to connect thin photovoltaic cells in integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/33; manufacture or treatment of encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/80; manufacture or treatment of integrated devices, or assemblies of multiple devices, comprising at least one element in which radiation controls the flow of current H10F39/00) · CPC title

• H10F77/14 Primary

  Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies · CPC title

• H10F30/225 Primary

  the potential barrier working in avalanche mode, e.g. avalanche photodiodes · CPC title

• H10F77/147

  Shapes of bodies · CPC title