Nitride Semiconductor Light Emitting Device Groove Extraction
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Solution Overview
Problem
Conventional nitride light emitting diodes suffer from low light extraction efficiency due to total reflection and absorption of light at the interface between the nitride semiconductor material and the outside environment, leading to reduced brightness and efficiency.
Innovation Solution
The formation of grooves in the nitride semiconductor layer, specifically through etching from a transparent electrode or ohmic layer, reduces the distance light travels within the diode, minimizing absorption and dispersion, and optimizing the groove geometry to enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is generated from the active layer and discharged to the outside through the nitride semiconductor material surface, then light extraction occurs, but total reflection occurs due to refractive index difference causing light to be reflected back into the diode
Solution Approach 1:
The patent applies curvature by forming grooves with curved sidewalls in the nitride semiconductor layer. These curved surfaces change the angle of incident light, allowing light that would normally undergo total reflection to be redirected at angles that enable extraction. The curved groove surfaces act as light-guiding structures that progressively bend light paths toward the surface, overcoming the total reflection barrier caused by refractive index mismatch.
Solution Approach 2:
The patent introduces a vertical dimension by etching grooves into the nitride semiconductor layer, creating a three-dimensional light extraction pathway. Instead of relying solely on the planar surface for light extraction, the grooves provide additional extraction surfaces at different depths and angles, effectively adding a vertical dimension to the light extraction process and increasing the overall extraction efficiency.
2Illumination intensity
If light travels a long distance within the nitride semiconductor layer to reach the surface, then light extraction may occur, but absorption and dispersion reduce the light intensity and efficiency
Solution Approach 1:
The patent segments the light extraction path by creating multiple grooves distributed across the nitride semiconductor layer. Instead of relying on a single long path to the surface, light can be extracted through multiple shorter paths via different grooves. This segmentation reduces the average distance light travels within the high-absorption nitride material, minimizing absorption and dispersion losses.
Solution Approach 2:
The grooves are pre-formed in the nitride semiconductor layer before light generation, creating ready-made extraction channels. This preliminary structuring ensures that light generated in the active layer can immediately follow optimized paths toward the surface through the grooves, rather than traveling through long, unoptimized paths that would result in significant absorption and dispersion.
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
This approach significantly improves light extraction efficiency by reducing light absorption and dispersion, thereby increasing the brightness and output of the light emitting diode.
Implementation Method 1
minimizing absorption and dispersion
Implementation Method 2
minimizing absorption and dispersion
Implementation Method 3
a total reflection condition occurs due to the difference in a refractive index between a nitride semiconductor material and the outside
Data Source
AI summary
A light emitting device having improved light extraction efficiency is disclosed. The light emitting device includes a nitride semiconductor layer including a first semiconductor layer, an active layer, and a second semiconductor layer, which are sequentially stacked, a portion of the first semiconductor layer being exposed to the outside by performing mesa etching from the second semiconductor layer to the portion of the first semiconductor layer, and at least one groove formed through a portion of the first semiconductor layer, the active layer, and the second semiconductor layer.