LED Adhesive Layer Spacing for Reliability and Light Extraction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face challenges in reliability due to inadequate adhesive strength between semiconductor layers and electrodes, leading to reduced light extraction efficiency and product reliability.
Innovation Solution
A light emitting device structure is developed with an adhesive layer contacting the top surface of a conductive semiconductor layer and electrodes, where the adhesive layer is strategically positioned to enhance adhesive strength and light extraction, featuring a concave-convex pattern for increased surface area and refractive index optimization to improve reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adhesive layer is introduced between the semiconductor layer and electrode to improve adhesive strength, then reliability improves, but device structure complexity increases
Solution Approach 1:
An adhesive layer is introduced as an intermediary component between the semiconductor layer and the electrode. This adhesive layer serves as a mediator that enhances the bonding interface, preventing delamination and improving overall device reliability while maintaining a relatively simple structural configuration.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing conductive particles dispersed in a polymer matrix. This composite structure provides both adhesive bonding properties and electrical conductivity, allowing the device to maintain electrical pathways while improving mechanical adhesion between layers.
2Reliability
If the adhesive layer contacts both the semiconductor layer and electrode to maximize adhesive strength, then reliability improves, but light extraction efficiency decreases due to increased optical absorption
Solution Approach 1:
The adhesive layer is applied selectively only in regions where electrical connection is required, rather than covering the entire semiconductor surface. This localized application maintains strong electrical bonding where needed while preserving light extraction efficiency in regions where the adhesive layer is absent, allowing light to pass through the semiconductor layer without significant absorption.
Solution Approach 2:
Instead of applying adhesive uniformly across the entire interface, the adhesive is applied partially only to specific contact regions. This partial action approach provides sufficient adhesive strength for electrical connection while minimizing the total amount of adhesive material that could absorb light, thereby maintaining high light extraction efficiency.
Data Source
AI summary
Disclosed are a light emitting device and a light emitting device package. The light emitting device includes a light emitting structure including a first conductive semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer, an adhesive layer contacting a top surface of the first conductive semiconductor layer, a first electrode contacting a top surface of the first conductive semiconductor and a top surface of the adhesive layer, and a second electrode contacting the second conductive semiconductor layer, wherein the adhesive layer contacting the first electrode is spaced apart from the second electrode.