Group III-Nitride LED Light Extraction via Sidewall Roughening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Group III-nitride volumetric LED chips face challenges in achieving high-performance light extraction due to the lack of surface and sidewall roughening techniques, which are not effectively addressed by traditional cleaving or processing methods, leading to inefficient light extraction from materials like gallium nitride.
Innovation Solution
Implementing surface and sidewall roughening techniques, including 1-dimensional and 2-dimensional texturing, such as vertical striations and pyramidal features, to enhance light extraction efficiency by breaking quasi-guided light trajectories and increasing the extraction efficiency from both top and lateral surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional cleaving or processing methods are used on Group III-nitride materials, then the manufacturing process is simple, but surface and sidewall roughening is not achieved, resulting in poor light extraction efficiency
Solution Approach 1:
The patent applies chemical etching processes that selectively remove material based on crystallographic orientation, transforming the smooth sidewalls produced by traditional cleaving into roughened surfaces with enhanced light extraction properties. This changes the surface morphology parameters without fundamentally altering the manufacturing workflow
Solution Approach 2:
The patent replaces mechanical cleaving methods with chemical etching processes to achieve sidewall roughening. Instead of using physical force to separate and shape the crystal, chemical reactions selectively dissolve material to create the desired rough surface topology that enhances light extraction
2Loss of energy
If surface and sidewall roughening techniques are implemented, then light extraction efficiency is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent performs surface and sidewall roughening as an integrated step during the LED fabrication process, before final device assembly. By preparing the roughened surfaces in advance during manufacturing rather than as a separate post-processing step, the overall process complexity is minimized
Solution Approach 2:
The patent combines multiple functions into a single manufacturing step: the chemical etching process simultaneously creates sidewall roughening, defines device boundaries, and prepares surfaces for subsequent processing. This merging of functions reduces the total number of manufacturing steps required
3Device complexity
If only top surface roughness is applied, then the manufacturing process is simpler, but light extraction efficiency is limited to around 70%
Solution Approach 1:
The patent extends the roughening treatment from the traditional two-dimensional top surface to include the three-dimensional sidewalls of the LED structure. This addition of another dimension (vertical sidewalls) to the roughening process captures light that would otherwise be trapped by total internal reflection, achieving the target of over 80% extraction efficiency
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 combination of surface and sidewall roughening techniques boosts light extraction efficiency from 70% with only top roughness to approximately 82% with 1D and 2D sidewall roughness, effectively addressing the limitations of traditional methods and improving the external quantum efficiency of LED devices.
Implementation Method 1
modifying the sidewall facets in order to break these quasi-guided trajectories. This can be done by texturing of the sidewall facets
Data Source
AI summary
Embodiments of the present disclosures are directed to improved approaches for achieving high-performance light extraction from a Group III-nitride volumetric LED chips. More particularly, disclosed herein are techniques for achieving high-performance light extraction from a Group III-nitride volumetric LED chip using surface and sidewall roughening.