Stacked Photonic Crystal Semiconductor Structure for LED Light Extraction
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Solution Overview
Problem
Current LED photoelectric devices manufactured on heterogeneous substrates like sapphire, silicon carbide, and silicon suffer from low light-emitting efficiency due to the high refractive index of gallium nitride, which causes significant light reflection and confinement within the chip.
Innovation Solution
A semiconductor structure featuring a stacked photonic crystal structure with N-type and P-type semiconductor layers, where the stacked island structures are arranged to achieve selective reflection and a photonic energy band structure, enhancing light-emitting efficiency by altering the color of reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LED photoelectric devices are manufactured on heterogeneous substrates (sapphire, silicon carbide, silicon), then the manufacturing process can proceed, but light-emitting efficiency is low due to high refractive index of gallium nitride causing light reflection and confinement
Solution Approach 1:
The patent divides the chip surface into multiple stacked island structures with different heights and materials, creating a segmented photonic crystal structure. This segmentation allows different regions to have different refractive indices and optical properties, enabling selective light reflection and extraction while maintaining manufacturing feasibility on heterogeneous substrates.
Solution Approach 2:
The patent applies local quality by creating island structures with varying materials (e.g., AlN, GaN, AlGaN) and heights at different locations on the chip. Each local region has optimized optical properties tailored to its position, with taller islands providing different reflection characteristics compared to shorter islands, thereby improving overall light extraction efficiency.
2Illumination intensity
If gallium nitride is used for LED devices, then high brightness and efficiency can be achieved, but the high refractive index causes most light rays to be reflected and confined within the chip
Solution Approach 1:
The patent converts the harmful effect of high refractive index (which causes light reflection and confinement) into a beneficial feature by utilizing the refractive index differences between stacked island structures with varying materials and heights. The interfaces between these structures create selective reflection and extraction of light rays, transforming the原本的劣势 into an advantage for light management.
Solution Approach 2:
The patent introduces vertical dimensionality by stacking island structures of different heights, creating a three-dimensional photonic crystal structure. This vertical stacking adds a new dimension for light interaction, allowing light to be extracted through multiple interfaces at different heights, thereby overcoming the limitation of planar light extraction and improving overall brightness.
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 semiconductor structure improves light-emitting efficiency by enabling selective reflection and altering the color of reflected light through its photonic energy band structure, effectively addressing the low efficiency issues in existing LED devices.
Implementation Method 1
the stacked structure is a photonic crystal structure
Implementation Method 2
the stacked island structures enable the stacked structure to have a photonic energy band structure, the color of the reflected light changes due to different energy gap positions
Data Source
AI summary
A semiconductor structure includes: a stacked structure, including one stacked structure unit or a plurality of stacked structure units disposed along a horizontal direction, where each of the stacked structure units includes a plurality of stacked island structures separated from each other along the horizontal direction; and an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer sequentially laminated on the stacked structure. In the present disclosure, by providing the stacked structure, the light-emitting efficiency of the semiconductor device can be improved.