Hexagonal-Pyramid Substrate Protrusions for LED Light Extraction
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Solution Overview
Problem
The challenge is to improve light extraction efficiency in semiconductor light emitting elements without causing dislocations and deteriorating crystallinity when protrusions on the substrate are densely arranged, as circularly shaped convex portions lead to dislocations and increased thickness of semiconductor layers.
Innovation Solution
A substrate with hexagonal-pyramid shaped protrusions is used, where the sides of the bottom surfaces of adjacent protrusions are parallel, allowing for denser arrangement and improved light extraction efficiency, and the orientation of these protrusions relative to the substrate's A-axis direction influences crystal growth for enhanced crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If protrusions are densely arranged on the substrate to improve light extraction efficiency, then light extraction efficiency is improved, but dislocations occur and crystallinity is deteriorated when using circularly shaped convex portions
Solution Approach 1:
The invention replaces circular protrusions with hexagonal-pyramid shaped protrusions. The hexagonal geometry with flat sides and vertices distributes stress more evenly during crystal growth, preventing dislocation formation while maintaining dense arrangement for effective light scattering and extraction.
Solution Approach 2:
The invention uses hexagonal-pyramid shape instead of circular shape, introducing directional symmetry that aligns with the crystal structure. The hexagonal base with specific orientation relative to the substrate's A-axis provides controlled growth facets that guide crystal formation and prevent random dislocation.
2Loss of energy
If protrusions are densely arranged on the substrate, then light extraction efficiency is improved, but thickness of semiconductor layers must be increased to maintain flat surface
Solution Approach 1:
The hexagonal-pyramid shape with controlled side angles provides smoother transitions between protrusion surfaces, allowing semiconductor layers to conform more easily and achieve flat surfaces at reduced thickness compared to circular protrusions with potential groove formations.
3Loss of energy
If distance between protrusions is reduced to increase density, then light extraction efficiency is improved, but dislocations occur at nearest locations of adjacent protrusions
Solution Approach 1:
The hexagonal-pyramid geometry with flat sides and vertices creates uniform spacing and stress distribution even at reduced distances between protrusions. The vertices and flat sides provide well-defined growth fronts that prevent dislocation nucleation at proximity zones between adjacent protrusions.
Solution Approach 2:
The hexagonal shape with specific orientation provides directional control over crystal growth, creating stable growth patterns that maintain precision even when protrusions are densely packed, unlike circular shapes that create isotropic stress fields leading to dislocations.
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 configuration enables higher light extraction efficiency and produces semiconductor light emitting elements with excellent crystallinity and power, suitable for illumination and electronic devices.
Implementation Method 1
protrusions such as projections (projecting portions) are provided at an interface between a substrate and an n-type semiconductor layer to scatter the light propagating in the lateral direction by the protrusions, thereby improving the light extraction efficiency
Implementation Method 2
a laminated semiconductor layer having a light emitting diode (LED) structure including an n-type semiconductor layer, a light emitting layer and a p-type semiconductor layer is formed on a substrate
Data Source
AI summary
Disclosed is a semiconductor light emitting element (LC) provided with a substrate (110) having one surface on which plural hexagonal-pyramid-shaped protrusions (110b) are provided, a base layer (130) provided so as to be in contact with the surface on which the protrusions (110b) are provided, an n-type semiconductor layer (140) provided so as to be in contact with the base layer (130), a light emitting layer (150) provided so as to be in contact with the n-type semiconductor layer (140), and a p-type semiconductor layer (160) provided so as to be in contact with the light emitting layer (150). Each protrusion (110b) scatters light in lateral and oblique directions within the semiconductor light emitting element (LC). The protrusions are densely arranged on a substrate on which semiconductor layers are laminated, so that the light extraction efficiency is improved.