Nitride Semiconductor Light Extraction via Nano-Post Array
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Solution Overview
Problem
Conventional nitride-based semiconductor light emitting devices have high defect densities due to manufacturing limitations, which hinder improvements in internal quantum efficiency and the development of high-power LEDs, and require enhanced light extraction efficiency.
Innovation Solution
A nitride-based semiconductor light emitting device structure is developed with an n-clad layer comprising a first clad layer, a second clad layer, and a light extraction layer composed of an array of nano-posts, which diffract or scatter light generated in the active layer, improving external light extraction efficiency. The nano-posts are formed from materials with different refractive indices and are manufactured using hologram lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional sapphire/n-GaN/MQW/p-GaN structure is used, then manufacturing process is simple, but light extraction efficiency is low
Solution Approach 1:
The patent introduces a light extraction layer with a porous structure consisting of nano-posts (100-500 nm in diameter, 100-500 nm in height) formed from transparent materials such as SiO2, Si3N4, Al2O3, or TiO2. This porous structure increases the light extraction efficiency by scattering and diffracting light waves, reducing total internal reflection at the semiconductor-air interface while maintaining a relatively simple manufacturing process using standard semiconductor fabrication techniques.
Solution Approach 2:
The patent transitions from a conventional planar light extraction interface to a three-dimensional nanostructured surface with vertical posts. This dimensional change creates multiple light extraction pathways and increases the effective surface area for light emission, thereby improving light extraction efficiency without significantly complicating the manufacturing process.
2Reliability
If defect density is reduced through manufacturing improvements, then internal quantum efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates the light extraction layer with nano-posts structure into the device architecture during the manufacturing process itself, rather than requiring post-manufacturing modifications. The nano-posts are formed simultaneously with other device layers using standard fabrication sequences, thereby improving light extraction efficiency without adding significant manufacturing complexity or steps.
3Reliability
If light extraction layer with nano-posts is added, then light extraction efficiency is improved, but device structure becomes more complex
Solution Approach 1:
The patent merges the light extraction function with the existing device structure by integrating the nano-posts layer into the cladding layer or barrier layer architecture. The transparent material used for nano-posts is deposited and patterned within the existing manufacturing sequence, combining multiple functions (structural support, optical management, and electrical isolation) into a single integrated component rather than adding separate discrete elements.
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 device achieves improved light extraction efficiency by enhancing the external extraction of light, surpassing the limitations of conventional structures, as demonstrated by simulation results showing increased light output.
Implementation Method 1
the light extraction layer diffracting or/and scattering light generated in the active layer
Implementation Method 2
the light extraction layer diffracting or/and scattering light generated in the active layer
Implementation Method 3
The nano-posts may be formed of a material having a different refraction index from a material used in forming the first clad layer and the second clad layer
Data Source
AI summary
A nitride-based semiconductor light emitting device having an improved structure in which light extraction efficiency is improved and a method of manufacturing the same are provided. The nitride-based semiconductor light emitting device comprises an n-clad layer, an active layer, and a p-clad layer, which are sequentially stacked on a substrate, wherein the n-clad layer comprises a first clad layer, a second clad layer, and a light extraction layer interposed between the first clad layer and the second clad layer and composed of an array of a plurality of nano-posts, the light extraction layer diffracting or/and scattering light generated in the active layer.