Nanostructured LED Surface for Light Extraction
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Solution Overview
Problem
Light emitting diodes (LEDs) suffer from low light output due to total internal reflection, where light is confined within the device, and existing methods to improve light extraction efficiency, such as surface texturing, require precise control and are costly or difficult to fabricate.
Innovation Solution
The formation of nano structures on the light emitting surface of LEDs, including nano rods, agglomerations, and recesses, which are spaced apart to prevent total internal reflection and enhance light extraction, is achieved through specific layer lamination and etching processes without the need for complex surface texturing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If surface texturing techniques are used to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing complexity and cost increase due to precise control requirements
Solution Approach 1:
The patent changes the physical parameters of the semiconductor surface by forming nanostructures with specific height ranges (10-1000 nm) and density distributions. This modifies the optical properties to reduce total internal reflection and improve light extraction efficiency without requiring complex fabrication processes
Solution Approach 2:
The patent introduces vertical nanostructures (nano rods, nano pillars, nano cones) that add a vertical dimension to the surface topology. This three-dimensional structuring creates additional light extraction pathways and reduces the critical angle for total internal reflection, improving efficiency while using standard fabrication techniques
2Loss of energy
If micro cavity or resonant cavity structures are used to improve light extraction, then light extraction efficiency is improved, but manufacturing precision requirements increase significantly
Solution Approach 1:
Instead of requiring precise control of cavity thickness and resonance conditions, the patent uses nanostructures with height parameters in the 10-1000 nm range that provide broadband light extraction enhancement without resonant conditions, significantly reducing manufacturing precision requirements
Solution Approach 2:
The patent employs nanostructures that can be formed using standard semiconductor fabrication techniques rather than requiring specialized precision manufacturing processes, making the solution more cost-effective and easier to manufacture at scale
3Loss of energy
If hemispherical chip shape is used to improve light extraction, then light extraction efficiency is improved, but ease of manufacture decreases due to fabrication difficulty
Solution Approach 1:
Instead of changing the overall chip shape to hemispherical, the patent applies local nanostructuring to the light-emitting surface. This maintains the simple planar chip geometry for easy manufacturing while creating localized optical effects that improve light extraction efficiency
4Loss of energy
If hemispherical epoxy dome encapsulation is used to improve light extraction, then light extraction efficiency is improved, but ease of manufacture decreases due to fabrication difficulty
Solution Approach 1:
The patent applies nanostructures locally to the light-emitting surface rather than requiring global geometric modifications like hemispherical encapsulation. This maintains simple planar device geometry while achieving improved light extraction through localized optical effects
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 nano structures effectively reduce light confinement, increasing the amount of light emitted outside the device and improving light extraction efficiency without the fabrication challenges of existing methods.
Implementation Method 1
Light generated in a light emitting diode is mostly confined inside the diode due to total internal reflection with a critical angle at an interface between two media such as a semiconductor and air.
Data Source
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Figure 5a~5c
AI summary
The present invention relates to a light emitting device having nano structures for light extraction and a method for manufacturing the same, nano structures comprising nano rods, nano agglomerations, nano recesses, nano patterns with nano line widths, nano through-holes or a combination thereof, formed on a light emitting surface of a light emitting device, thereby enhancing the light extraction efficiency of the device.