Hollow Pillar Light Emitting Device for High Extraction Efficiency
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Solution Overview
Problem
The low light extraction efficiency of light emitting devices is primarily due to total reflection of light within the semiconductor layers, which reduces illumination output, and increasing current density to enhance efficiency decreases the device's reliability and lifespan.
Innovation Solution
The implementation of a light emitting device with a plurality of pillar structures featuring a hollow structure, which increases light scattering efficiency by creating a rough outer and inner surface, thereby enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current density is increased to enhance light emitting efficiency, then illumination output is improved, but reliability and usage life of the device decrease
Solution Approach 1:
The device is segmented into multiple independent pillar structures (plural) distributed across the semiconductor layer. Each pillar acts as an independent light extraction unit, collectively improving overall illumination output without requiring excessive current density in any single region, thereby maintaining device reliability.
Solution Approach 2:
The invention transitions from a planar surface structure to a three-dimensional pillar structure with hollow interiors. This dimensional change creates additional light extraction pathways through the vertical dimension and internal hollow spaces, improving light emission efficiency without increasing current density, thus preserving device lifespan.
2Ease of manufacture
If a smooth semiconductor layer surface is used, then manufacturing is simpler, but light extraction efficiency is low due to total reflection
Solution Approach 1:
The pillar structures feature curved outer surfaces and internal hollow cavities, replacing flat smooth surfaces with curved geometries. This curvature creates multiple light reflection angles, reducing total internal reflection and improving light extraction efficiency while maintaining manufacturing feasibility through standard photolithography and etching processes.
Solution Approach 2:
The hollow structure within each pillar creates a porous-like internal geometry that disrupts total internal reflection. The hollow cavities provide additional interfaces for light extraction, improving optical efficiency without requiring complex surface treatments or coatings that would complicate manufacturing.
3Loss of energy
If a hollow structure with rough surfaces is formed in pillar structures, then light scattering efficiency and extraction efficiency are increased, but device structure becomes more complex
Solution Approach 1:
The complex hollow structure is divided into multiple discrete pillar units distributed across the semiconductor layer. Each pillar contains a simplified hollow cavity formation achieved through standard photolithography patterning and etching processes, making the overall complex structure manufacturable using conventional fabrication techniques.
Solution Approach 2:
The invention optimizes key parameters of the pillar structures including diameter (5-20 micrometers), spacing (10-30 micrometers), and hollow cavity dimensions to achieve effective light scattering. By carefully controlling these parameters within specific ranges, the structure achieves high light extraction efficiency while remaining compatible with standard manufacturing capabilities.
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 hollow pillar structure design effectively increases light extraction efficiency by scattering light within the device, improving illumination output without compromising the device's reliability or lifespan.
Implementation Method 1
the hollow pillar structure design effectively increases light extraction efficiency by scattering light within the device
Data Source
AI summary
A light emitting device is provided which includes a substrate, a first semiconductor layer having a first region and a second region on the substrate; ac active layer is formed on the first region of the first semiconductor layer; a second semiconductor layer is formed on the active surface layer and the portion surface of the second semiconductor layer is a rough surface; a plurality of pillar structures with a hollow structure, and both of the outer surface and inner surface of the pillar structures are rough surface; a transparent conductive layer is formed to cover the plurality of pillar structures; a first electrode is formed on the transparent conductive layer; and a second electrode is formed on the second region of the first semiconductor layer.