Sapphire Substrate with Irregular Hexagonal Pyramids for LED Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting diodes (LEDs) suffer from low light extraction efficiency due to photon depletion mechanisms, limiting their brightness and application range.
Innovation Solution
A sapphire substrate with irregular hexagonal pyramid structures is used, featuring a pitch less than 10 μm, with symmetrical cross-sectional angles and a (0001) surface area of 10% to 60% of the projected area, enhancing light diffusion and reducing reflection, thereby improving light emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional flat LED substrate is used, then the device structure is simple and manufacturing is easy, but light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The patent applies curvature by forming three-dimensional pyramid structures on the substrate surface instead of using a flat plane. The pyramidal geometry with sloped facets creates multiple light reflection paths, reducing total internal reflection and improving light extraction efficiency while maintaining a relatively simple manufacturing process through standard semiconductor fabrication techniques
2Manufacturing precision
If the pitch of pyramid structures is increased, then manufacturing precision requirements are reduced, but light scattering efficiency decreases
Solution Approach 1:
The patent optimizes the pitch parameter of the pyramid structures to a specific range (0.5-5 μm) to achieve the best balance between light scattering efficiency and manufacturing feasibility. This parameter optimization ensures sufficient light scattering effect while remaining compatible with standard semiconductor manufacturing capabilities
3Reliability
If the (0001) surface area is increased, then epitaxy process difficulty increases, but light emission quality improves
Solution Approach 1:
The patent applies local quality by creating a heterogeneous surface with different crystallographic orientations - the pyramid facets expose different crystal planes while maintaining controlled (0001) surface areas. This local variation in surface properties optimizes both light emission quality through enhanced light-matter interaction and epitaxy compatibility by preserving sufficient c-plane areas
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 substrate design significantly increases light extraction efficiency and simplifies the epitaxy process by optimizing the arrangement of pyramid structures, leading to enhanced LED performance.
Implementation Method 1
a patterned LED substrate, for example, an LED substrate constituted with a plurality of cones or platform structures is used to scatter the light emitted from the LED, so as to reduce the total reflection
Data Source
AI summary
A light emitting diode (LED) substrate includes a sapphire substrate which is characterized by having a surface consisting of irregular hexagonal pyramid structures, wherein a pitch of the irregular hexagonal pyramid structure is less than 10 μm. A symmetrical cross-sectional plane of each of the irregular hexagonal pyramid structures has a first base angle and a second base angle, wherein the second base angle is larger than the first base angle, and the second base angle is 50° to 70°. This LED substrate has high light-emitting efficiency.