GaN Light Emitting Device with Irregular Convex-Concave Pattern
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Solution Overview
Problem
Light emitting devices face issues with current crowding and optical loss due to high resistance in GaN layers and absorption by substrates, leading to inefficient light emission and dispersal of electric current.
Innovation Solution
A light emitting device with an irregular convex-concave pattern on the first conductivity-type semiconductor layer, formed through photolithography and etching, enhances current dispersal and light extraction by creating convex and concave portions with varying heights and depths, allowing for improved current distribution and refractive light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent electrode layer is formed on the P-GaN layer to achieve uniform spreading of electric current, then current dispersing performance is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating an irregular convex-concave pattern on the N-GaN layer surface, where different regions (convex and concave portions) have different properties. This patterned structure provides localized current dispersion pathways without requiring an additional transparent electrode layer, thus improving current dispersing performance while avoiding increased device complexity
Solution Approach 2:
The patent uses curvature by forming convex portions with curved surfaces on the N-GaN layer. These curved convex structures help distribute current more uniformly across the electrode contact area, improving current dispersing performance through geometric modification rather than adding complex electrode layers
2Illumination intensity
If the GaN layer has a high index of refraction to enable light generation, then light emission capability is improved, but optical loss increases due to total internal reflection
Solution Approach 1:
The patent applies curvature by forming convex portions with curved surfaces on the N-GaN layer. These curved surfaces modify the light extraction interface, reducing total internal reflection and improving light extraction efficiency while maintaining the high refractive index benefit for light generation
Solution Approach 2:
The patent transitions from a flat two-dimensional interface to a three-dimensional convex-concave patterned interface. This dimensional change creates multiple light extraction pathways at different angles and positions, reducing optical loss caused by total internal reflection while preserving the light emission capability of the high refractive index GaN layer
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 irregular pattern effectively disperses electric current and enhances light extraction efficiency, reducing current crowding and optical loss, thereby improving both current dispersing performance and luminous efficacy.
Implementation Method 1
The first conductivity-type semiconductor layer including the irregular convex-concave pattern is exposed from the active layer and the second conductivity-type semiconductor layer
Implementation Method 2
a high index of refraction of the GaN layer may cause total internal reflection at a surface of the GaN layer, causing loss of light inside the GaN layer instead of allowing emission of light to the outside
Data Source
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AI summary
A light-emitting device according to an exemplary embodiment of the present invention includes a first conductivity-type semiconductor layer (130) disposed on a substrate (110); an active layer (140) disposed on the first conductivity-type semiconductor layer; a second conductivity-type semiconductor layer (150) disposed on the active layer; and an irregular convex-concave pattern (190) disposed on a surface of the first conductivity-type semiconductor layer. The irregular convex-concave pattern includes convex portions and concave portions, and the convex portions have irregular heights and the concave portions have irregular depths. The first conductivity-type semiconductor layer (130) including the irregular convex-concave pattern (190) is exposed from the active layer (140) and the second conductivity-type semiconductor layer (150).