AlGaInP Semiconductor Window Layer for Infrared LED Light Extraction

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Solution Overview

Problem

Conventional infrared light-emitting diodes are costly due to the bonding process and metal reflective layer, and they struggle to achieve a larger far field angle of light, which is necessary for applications like touch panels.

Innovation Solution

A light-emitting device with a semiconductor window layer made of AlGaInP series material is used between the substrate and the light-emitting stack, providing a single layer structure that acts as a reflective mirror, enhancing lateral light reflection and extraction, and simplifying the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bonding process and metal reflective layer are used in conventional infrared light-emitting diodes, then the device structure is complete, but the manufacturing cost increases

Engineering Contradiction:

Improvedevice structure completenessVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the metal reflective layer from the conventional LED structure and replaces it with a semiconductor window layer that provides both the reflective function and serves as part of the light-emitting stack, thereby eliminating the need for separate bonding processes and reducing manufacturing complexity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The semiconductor window layer combines multiple functions: it acts as a reflective mirror for lateral light extraction, serves as a structural component of the light-emitting stack, and eliminates the need for separate bonding processes, thereby simplifying the overall device structure

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If conventional infrared light-emitting diodes are designed for standard applications, then the manufacturing process is simplified, but the far field angle of light is insufficient for touch panel applications

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidfar field angle

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent modifies the optical properties locally at the semiconductor window layer to enhance lateral light extraction and increase the far field angle, while maintaining the overall simplicity of the manufacturing process through the single-layer structure

Inventive Principle:

Principle #3Local quality

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

This design increases the output luminous power by 17% for 850 nm and 4% for 940 nm wavelengths, while reducing manufacturing costs and achieving a larger far field angle, outperforming conventional devices with Distributed Bragg Reflector structures.

Implementation Method 1

providing a single layer structure that acts as a reflective mirror, enhancing lateral light reflection and extraction

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS10381512B2Light-emitting device

Publication Date: 2019.08.13 ENNOSTAR CORP

AI summary

The present disclosure provides a light-emitting device. The light-emitting device includes a substrate, a light-emitting stack on the substrate, and a semiconductor window layer comprising AlGaInP series material disposed between the substrate and the light-emitting stack.