# US 12,326,519 B2 · Responsivity enhanced photodetector with photon-trapping nanostructures

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- Number: US 12,326,519 B2
- Document ID: US12326519B2
- Status: Granted
- Kind: B2
- Application number: 18/223,481
- Filed: 2023-07-18
- Published: 2025-01-23
- Granted: 2025-06-10
- Earliest claimed: 2023-07-18
- Assignees: Attollo Engineering, LLC
- Applicants: Attollo Engineering, LLC
- Inventors: Bora Onat; M. Saif Islam
- Web page: https://patentgrep.com/patent/US12326519B2

## CPC

- G01S 7/4816: {of receivers alone}
- H10F 39/021: {of image sensors having active layers comprising only Group III-V materials, e.g. GaAs, AlGaAs or InP}
- H10F 39/184: {Infrared image sensors}
- H10F 39/191: {Photoconductor image sensors}
- H10F 39/199: {Back-illuminated image sensors}
- H10F 39/806: {Optical elements or arrangements associated with the image sensors}
- H10F 39/8063: {Microlenses}
- G01S 17/89: for mapping or imaging
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A back-illuminated photo detector array (PDA) includes a front side and a back side. The back side receives optical energy incident on the back side at an incident direction. The front side includes a detection layer that includes detection structures and a plurality of photon-trapping nanostructures (PTN). The PTN cause optical energy incident on the back side to disperse in a direction perpendicular to the incident direction, and thereby improve an absorption efficiency of the back-illuminated PDA.

## Claims

### Claim 1

Photo Detector Array (PDA), comprising:
a back side that receives optical energy incident on the back side at an incident direction; and
a front side that includes a detection layer that absorbs the optical energy incident on the back side via a substrate, wherein the detection layer includes a plurality of detector structures and fill regions between adjacent detector structures, wherein the fill regions are filled with a dielectric material and include a plurality of nanostructures which cause optical energy incident on the fill regions to disperse perpendicularly to the incident direction to be absorbed by an absorber layer of the plurality of detector structures.

### Claim 2 (depends on 1)

The PDA of claim 1, wherein the fill regions further include a blocking structure that causes optical energy dispersed perpendicularly away from an adjacent detection structure to be reflected back towards the adjacent detection structure.

### Claim 3 (depends on 1)

The PDA of claim 1, wherein the optical energy is not received via a micro-lens array at the back side.

### Claim 4 (depends on 1)

The PDA of claim 1, wherein the plurality of nanostructures is a first plurality of nanostructures, and wherein the plurality of detection structures include an absorber layer that includes a second plurality of nanostructures that cause the optical energy received at the plurality of detection structure to disperse perpendicularly to the incident direction within the absorber layer.

### Claim 5 (depends on 1)

The PDA of claim 1, wherein the plurality of nanostructures are filled with a dielectric material.

### Claim 6 (depends on 1)

The PDA of claim 1, the fill region is filled with a first material with a first dielectric constant, and the plurality of nanostructures are filled with a second material with a second dielectric constant substantially less than the first dielectric constant.

### Claim 7 (depends on 1)

The PDA of claim 1, wherein the nanostructures have a diameter less than a wavelength of the incident optical energy.

### Claim 8 (depends on 1)

The PDA of claim 1, where the PDA is a Mesa-Type PDA that includes one or more detection structures selected from the group consisting of:
PIN detectors;
Schottky detectors;
solar cell detectors; and
nBn-type detectors.

### Claim 9 (depends on 1)

The PDA of claim 1, wherein the fill regions separate adjacent detection structures from one another.

### Claim 10 (depends on 1)

The PDA of claim 1, wherein the fill regions do not include an absorber layer.

### Claim 11 (depends on 1)

The PDA of claim 1, wherein the adjacent detector structures absorb the optical energy incident on the back side via the substrate, and the fill regions do not absorb the optical energy incident on the back side via the substrate.

### Claim 12

A method, comprising:
receiving, at a back surface of a photo detector array (PDA), incident optical energy in an incident direction;
absorbing, at adjacent detection structures of the photo detector, the optical energy; and
using photon-trapping nanostructures to cause optical energy incident on fill regions between adjacent detection structures that are filled with a dielectric material to disperse perpendicularly to the incident direction towards the adjacent detection structures.

### Claim 13 (depends on 12)

The method of claim 12, further comprising:
wherein the photon-trapping nanostructures are a first plurality of photon trapping nanostructures, and further comprising using a second plurality of photon-trapping nanostructures to cause optical energy received at an absorber layer of the detection structures to disperse perpendicularly to the incident direction within the absorber layer.

### Claim 14 (depends on 12)

The method of claim 12, wherein the fill regions separate adjacent detection structures from one another.

### Claim 15 (depends on 12)

The method of claim 12, wherein the fill regions do not include an absorber layer.

### Claim 16 (depends on 12)

The method of claim 12, wherein the adjacent detector structures absorb the optical energy incident on the back surface via a substrate, and the fill regions do not absorb the optical energy incident on the back surface via the substrate.

### Claim 17

A Photo Detector Array (PDA), comprising:
a back side that includes a substrate; and
a front side that includes a detection layer that absorbs optical energy incident on the front side in an incident direction, wherein the detection layer includes a plurality of detector structures and fill regions between adjacent detector structures, wherein the fill regions are filled with a dielectric material and include a plurality of nanostructures, and wherein the plurality of nanostructures cause optical energy received at the fill region to disperse perpendicularly to the incident direction to be absorbed by an absorber layer of the plurality of detector structures.

### Claim 18 (depends on 17)

The PDA of claim 17, wherein the plurality of nanostructures is a first plurality of nanostructures, and further comprising:
a second plurality of nanostructures in an absorber layer that cause the optical energy received at the plurality of detection structures to disperse perpendicularly to the incident direction within the absorber layer.

### Claim 19 (depends on 17)

The PDA of claim 17, further comprising:
at least one electrical circuit disposed in the fill regions.

### Claim 20 (depends on 19)

The PDA of claim 19, further comprising:
a dielectric film layer formed upon the electrical circuit, wherein the plurality of nanostructures is a first plurality of nanostructures, and further comprising another plurality of nanostructures in the dielectric film layer.

### Claim 21

A photo detector structure, comprising:
a detection surface configured to receive incident light from an incident direction; and
an absorption layer that absorbs optical energy from the detection surface and generates an electrical signal indicative of characteristics of the received energy, and wherein the absorption layer absorbs optical energy dispersed towards the photo detector structure in a direction perpendicular to the incident direction by a plurality of photon trapping nanostructures arranged in a fill region adjacent to the photo detector structure that is filled with a dielectric material.