Light-Emitting Device Textured Sidewall for Light Extraction
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Solution Overview
Problem
Conventional light emitting devices suffer from reduced light extraction efficiency due to total internal reflection caused by the flat surface of their transparent substrates, which have a different refractive index than the external environment.
Innovation Solution
A light emitting device with a substrate having a sidewall comprising a substantially flat first area and a substantially textured second area, fabricated using a method involving a semiconductor epitaxial layer, etching protection layer, and discontinuous laser beam to create a mesa structure and textured surface, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat substrate surface is used, then the manufacturing process is simple, but the light extraction efficiency is reduced due to total internal reflection
Solution Approach 1:
The substrate sidewall is divided into two distinct areas: a first area with a substantially flat morphology and a second area with a substantially textured morphology. This local differentiation allows the flat first area to maintain ease of manufacture while the textured second area enhances light extraction efficiency by reducing total internal reflection.
Solution Approach 2:
The substrate sidewall is segmented into multiple regions (first area and second area) with different surface characteristics. The first area maintains simplicity for manufacturing, while the second area introduces texturing to improve optical performance, thus resolving the contradiction between manufacturing ease and light extraction efficiency.
2Reliability
If a textured sidewall structure is created, then light extraction efficiency is improved, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of texturing the entire substrate sidewall, only a portion (the second area) is textured while the first area remains flat. This partial application of texturing achieves the necessary light extraction improvement without unnecessarily increasing device complexity and manufacturing difficulty.
Solution Approach 2:
The texturing is applied locally to the second area of the sidewall rather than uniformly across the entire substrate. This localized approach improves light extraction efficiency where needed while minimizing the increase in overall device complexity and manufacturing complexity.
3Reliability
If the entire sidewall is textured, then light extraction efficiency is maximized, but manufacturing difficulty increases significantly
Solution Approach 1:
The texturing process is applied partially to only the second area of the sidewall rather than the entire sidewall. This partial texturing achieves sufficient light extraction improvement while significantly reducing manufacturing difficulty compared to full sidewall texturing.
Solution Approach 2:
The sidewall is segmented into a first area that remains flat and a second area that is textured. This segmentation allows the manufacturing process to focus texturing efforts only where needed, reducing overall fabrication difficulty while maintaining adequate light extraction efficiency.
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 textured sidewall structure significantly improves light extraction efficiency by reducing total internal reflection and enhancing the emission of light from the device.
Implementation Method 1
producing a plurality of discontinuous holes on the substrate by a discontinuous laser beam
Implementation Method 2
etching the plurality of discontinuous holes
Implementation Method 3
the total internal reflection (TIR) occurs when a light A emitted from the active layer 122
Implementation Method 4
The light extraction efficiency of the light emitting device may be enhanced by the discontinuous structure on the sidewall
Data Source
AI summary
A light emitting device and a method of fabricating thereof are provided. The method of fabricating the light emitting device comprises: providing a substrate having a first major surface and a second major surface; forming a plurality of light-emitting stacks on the first major surface; forming an etching protection layer on each of the light emitting stacks; forming a plurality of holes by a discontinuous laser beam on the substrate; etching the plurality of holes; and slicing off the substrate along the plurality of holes to form a light emitting device. The light emitting device has a substrate wherein the sidewall of the substrate comprising a first area with a substantially flat surface and a second area with substantially textured surface.