LED Chip Growing Base Geometry for Light Extraction and Delamination Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED chips using sapphire substrates suffer from light scattering, leading to reduced light emitting efficiency due to the absorption of scattered light by semiconductor layers, resulting in wasted light and lower luminosity.
Innovation Solution
The use of a growing base with a specific geometry, such as a slanted or curved side surface, in conjunction with an encapsulant that covers the growing base, enhances structural reliability and prevents delamination, while allowing more light to be emitted by forming the LED chip with a translucent substrate that allows light to pass through, thereby improving light emitting efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sapphire substrate is used in LED chip fabrication, then the substrate provides mechanical support and allows epitaxial growth, but the transparent material scatters light in all directions without focusing, causing light waste and reduced light emitting efficiency
Solution Approach 1:
The patent applies asymmetry by designing the substrate with a non-planar surface featuring a convex protrusion or conical structure. This asymmetric geometry focuses the scattered light in a specific direction rather than allowing omnidirectional scattering, thereby improving light extraction efficiency while maintaining the substrate's mechanical support function
Solution Approach 2:
The patent utilizes curvature by forming a convex protrusion or conical structure on the substrate surface. This curved geometry acts as a light-focusing element that redirects scattered light waves, converting the previously wasted scattered light into useful directed light output, thus improving overall light emitting efficiency
2Reliability
If the encapsulant covers the entire growing base, then structural reliability is improved, but delamination occurs between the encapsulant and growing base
Solution Approach 1:
The patent applies asymmetry by designing the growing base with a convex protrusion or conical structure that creates an asymmetric bonding interface with the encapsulant. This asymmetric geometry increases the contact area and mechanical interlocking between the encapsulant and substrate, preventing delamination while maintaining structural reliability
Solution Approach 2:
The patent utilizes curvature by forming a convex protrusion on the growing base surface. This curved structure increases the surface area for bonding between the encapsulant and substrate, creating a more stable bond that resists delamination forces while maintaining the protective encapsulation function
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 solution significantly increases total light efficiency and reduces light loss, providing broader and more uniform light output by preventing delamination and optimizing the light path through the use of a translucent substrate and encapsulant geometry.
Implementation Method 1
An LED chip is a semiconductor element constituted mainly by, for example, group III-V compound semiconductor materials. Since such semiconductor materials have a characteristic of converting electricity into light, when a current is applied to the semiconductor materials, electrons therein are combined with holes and excessive energy are released in form of light
Implementation Method 2
The growing base comprises a third surface facing the LED structure layer, a fourth surface opposite to the third surface, and a side surface connected between the third surface and the fourth surface. The area of the fourth surface is larger than the area of the third surface. In addition, the encapsulant covers the fourth surface of the growing base and exposing the two electrodes
Data Source
AI summary
A light emitting device is provided with a growing base having specific geometry to prevent delamination between the encapsulant and the growing base, and thereby enhance structural reliability of the light emitting device. Furthermore, the light emitting efficiency as well as uniformity of light output of the light emitting device can be improved by forming the side surface of the growing base with at least a curved portion or slanted portion, and uneven structures can be formed on the curved portion or slanted portion to further improve the uniformity of light output. Furthermore, the light emitting diode chips can be fabricated by taking batch processing on the growing substrate, as provided in the wafer-level structure, with the advantages of saving cost, improving yield, etc.