LED Chip Microstructured Substrate Light Extraction
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Solution Overview
Problem
Conventional light emitting diode (LED) chips face inefficiencies in light extraction due to high probabilities of total internal reflection, limiting their brightness and efficiency.
Innovation Solution
The LED chip features a substrate with microstructures on its growth surface, where the area not occupied by these microstructures is between 10% and 50% of the total surface, enhancing light scattering and extraction efficiency. The microstructures, such as protrusions or depressions, are designed with specific dimensions and shapes to optimize light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional smooth substrate surface is used, then the manufacturing process is simple, but the light extraction efficiency is low due to high total internal reflection
Solution Approach 1:
The substrate surface is transformed from a smooth planar surface to one with micro-scale protrusions and depressions. This curvature modification at the micro-scale level creates multiple light scattering interfaces, reducing total internal reflection and improving light extraction efficiency without requiring complex manufacturing processes
Solution Approach 2:
The substrate is designed with a porous-like microstructure consisting of protrusions and depressions. This micro-roughened surface structure increases the effective surface area and creates multiple refraction interfaces, enabling better light extraction while maintaining manufacturing feasibility through standard semiconductor processing techniques
2Loss of energy
If the microstructures occupy a large area of the growth surface, then light scattering is enhanced, but the area available for light emitting diode element layer deposition is reduced
Solution Approach 1:
The substrate surface is designed with non-uniform local structures - micro-scale protrusions and depressions distributed across the surface. These localized microstructures provide light scattering functionality in specific regions while leaving sufficient flat areas for LED element layer deposition, achieving both light extraction enhancement and adequate deposition area
Solution Approach 2:
The microstructures are designed to occupy a controlled portion of the substrate surface (protrusion area ratio between 0.05 and 0.5). This partial coverage provides sufficient light scattering effect while maintaining adequate flat surface area for device fabrication, avoiding excessive microstructure density that would compromise deposition area
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 design significantly improves light extraction efficiency by reducing the probability of total internal reflection, leading to enhanced output power and brightness of the LED chip.
Implementation Method 1
enhancing light scattering and extraction efficiency
Data Source
AI summary
A light emitting diode chip including a substrate and a light emitting diode element layer is provided. The substrate has a growth surface and a plurality of microstructures on the growth surface. An area of the growth surface occupied by the microstructures is A1 and an area of the growth surface not occupied by the microstructures is A2, such that A1 and A2 satisfy the relation of 0.1≦A2/(A1+A2)≦0.5. The light emitting diode element layer is disposed on the growth surface of the substrate.