LED Three-Dimensional Nano-Structures for Light Extraction
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Solution Overview
Problem
The extraction efficiency of light emitting diodes (LEDs) is low due to a limited contact area between the N-type semiconductor layer and the active layer, resulting in low electron-hole recombination density and sparse photon emission.
Innovation Solution
The formation of three-dimensional nano-structures on the surface of the semiconductor layer increases the contact area with the active layer, enhancing electron-hole recombination and photon extraction efficiency by creating a patterned surface for the active layer and semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical LED structure with flat semiconductor layers is used, then the device structure is simple and easy to manufacture, but the contact area between the N-type semiconductor layer and the active layer is limited, resulting in low extraction efficiency
Solution Approach 1:
The patent transforms the flat two-dimensional interface between the N-type semiconductor layer and the active layer into a three-dimensional wavy structure. This dimensional change increases the contact area from a simple plane to a complex undulating surface, thereby enhancing electron-hole recombination and light extraction efficiency without fundamentally changing the manufacturing process
Solution Approach 2:
The patent introduces a wavy structure with curved surfaces instead of a flat interface. The undulating shape creates multiple peaks and valleys that increase the effective contact area between layers, improving the interaction between electrons and holes while maintaining structural integrity and ease of fabrication
2Reliability
If the contact area between the N-type semiconductor layer and the active layer is increased by creating a wavy structure, then the electron-hole recombination density and photon emission are enhanced, but the device structure becomes more complex
Solution Approach 1:
The patent achieves increased contact area by utilizing the third dimension through a wavy structure, rather than expanding the lateral footprint or adding multiple discrete layers. This approach enhances extraction efficiency while maintaining a relatively compact and manufacturable device structure
Solution Approach 2:
The wavy structure introduces dynamic undulations to the otherwise static flat interface. These controlled waves provide increased surface area for electron-hole recombination while maintaining structural stability, balancing performance enhancement with manufacturing feasibility
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 increased contact area and patterned surface structure improve the light extraction efficiency of LEDs by increasing electron-hole recombination density and enhancing photon emission.
Implementation Method 1
holes in the P-type semiconductor layer and photons in the N-type semiconductor layer can enter the active layer and combine with each other to emit visible light
Implementation Method 2
LEDs are semiconductors that convert electrical energy into light
Implementation Method 3
the extraction efficiency of LEDs is low because the contact area between the N-type semiconductor layer and the active layer is not large enough
Data Source
AI summary
A method for making light emitting diode includes following steps. A substrate is provided. A first semiconductor layer is grown on a surface of the substrate. A patterned mask layer is located on a surface of the first semiconductor layer, and the patterned mask layer includes a number of bar-shaped protruding structures, a slot is defined between each two adjacent protruding structures to expose a portion of the first semiconductor layer. The exposed first semiconductor layer is etched to form a protruding pair. A number of three-dimensional nano-structures are formed by removing the patterned mask layer. An active layer and a second semiconductor layers are grown on the number of three-dimensional nano-structures in that order. A first electrode is electrically connected with the first semiconductor layer. A second electrode is located to cover the entire surface of the second semiconductor layer which is away from the active layer.