Light Detector Junction Layout for Secondary Photon Crosstalk

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Solution Overview

Problem

Existing light detectors face challenges in minimizing crosstalk, which affects the accuracy of photon detection, due to secondary photons generated in the junction region being reflected back and interfering with the detection process.

Innovation Solution

The light detector design incorporates a first insulating portion with an inclined surface and voids, positioned at the same height as the junction region, to reflect secondary photons downward, reducing crosstalk by increasing the refractive index difference and utilizing a quenching part to suppress avalanche breakdown, thereby enhancing detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional light detector structure is used, then the device is simple to manufacture, but crosstalk occurs due to secondary photons being reflected back and interfering with detection

Engineering Contradiction:

Improvephoton detection accuracyVSAvoiddetector structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The insulating portion is divided into multiple segments: a first insulating portion with an inclined surface and a second insulating portion with a planar surface. This segmentation allows each part to perform a specific function - the inclined surface reflects secondary photons while the planar surface provides a stable reference plane, thereby reducing crosstalk without overly complicating the overall structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insulating portion acts as an intermediary element between the junction region and the surrounding environment. By introducing this intermediate structure with specific surface configurations, secondary photons are redirected away from the detection region, preventing them from causing crosstalk while maintaining the integrity of the detection system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the junction region is kept simple, then manufacturing is easier, but stress concentration occurs leading to lower yield

Engineering Contradiction:

Improvemanufacturing yieldVSAvoidjunction region structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The insulating portion is positioned locally adjacent to the junction region, providing stress relief precisely where needed. The inclined surface and planar surface configuration creates a localized structural modification that reduces stress concentration at the junction without requiring complex changes to the entire device structure, thereby improving manufacturing yield.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If secondary photons are allowed to reflect naturally, then the detection process is simpler, but crosstalk increases reducing detection accuracy

Engineering Contradiction:

Improvedetection accuracyVSAvoidmanufacturing simplicity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The first insulating portion features an asymmetric inclined surface rather than a symmetric planar structure. This asymmetric configuration is specifically designed to reflect secondary photons in a controlled manner away from the detection region, reducing crosstalk while maintaining manufacturing feasibility through standard fabrication techniques.

Inventive Principle:

Principle #4Asymmetry

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively suppresses crosstalk, improving the accuracy of photon detection and reducing stress-related manufacturing issues, leading to increased yield and sensitivity of the light detector.

Implementation Method 1

The first insulating portion has an inclined surface inclined with respect to a first direction perpendicular to the p-n junction surface and includes void. The inclined surface is provided at a same height as at least a portion of the junction region and crosses the second direction from the junction region toward the first insulating portion.

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

The quenching part is electrically connected to the second semiconductor region.

Methodology Applied

Scientific EffectAvalanche breakdown: Avalanche Breakdown

Data Source

PatentUS12009442B2Light detector, light detection system, lidar device, and moving body

Publication Date: 2024.06.11 KK TOSHIBA

AI summary

According to one embodiment, a light detector includes a junction region, a first insulating portion, and a quenching part. The junction region includes a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type. The second semiconductor region is provided on the first semiconductor region and forms a p-n junction surface with the first semiconductor region. The first insulating portion has an inclined surface inclined with respect to a first direction perpendicular to the p-n junction surface and includes void. The inclined surface is provided at a same height as at least a portion of the junction region and crosses the second direction from the junction region toward the first insulating portion. The quenching part is electrically connected to the second semiconductor region.