Group III Nitride LED Surface Texturing via Masked Wet Etching
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Solution Overview
Problem
The existing methods for texturing Group III Nitride surfaces in LEDs are difficult to control, leading to variations in texture depth, crystal feature size, and light extraction efficiency, which can result in decreased radiant flux and reliability issues.
Innovation Solution
The use of a photolithographically defined mask, such as a transparent dielectric mask, combined with wet etching to create a controlled array of Group III Nitride surface features, including truncated cones with specific geometric configurations, to enhance light extraction and improve surface consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If existing texturing methods are used on Group III Nitride surfaces, then light extraction can be enhanced, but the texture depth, crystal feature size, and light extraction efficiency vary uncontrollably
Solution Approach 1:
A mask layer is applied to the Group III Nitride surface before texturing to predefine the locations where texturing features will form. This preliminary masking action ensures that subsequent texturing processes create features only at predetermined locations with controlled dimensions, eliminating the uncontrolled variations in texture depth and crystal feature size while maintaining light extraction enhancement
2Illumination intensity
If existing texturing methods are used on Group III Nitride surfaces, then light extraction can be enhanced, but the crystal feature size varies uncontrollably
Solution Approach 1:
The mask layer is deposited and patterned beforehand to establish precise geometric boundaries for texturing features. This preliminary action constrains the crystal feature size to match the mask pattern dimensions, ensuring uniform and controlled feature sizes across the surface while still achieving the desired light extraction enhancement through the textured structures
3Illumination intensity
If existing texturing methods are used on Group III Nitride surfaces, then light extraction can be enhanced, but reliability issues arise due to process variations
Solution Approach 1:
By applying the mask layer before texturing, the process establishes predetermined locations and dimensions for all texturing features. This preliminary action eliminates process variations that would otherwise lead to inconsistent light extraction efficiency across devices, thereby improving reliability while maintaining the light extraction enhancement benefit
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 allows for enhanced light extraction, improved performance averages, increased yields, and reduced reliability risks by providing a controlled combination of textured and untextured areas with defined aspect ratios and angled sidewalls.
Implementation Method 1
wet chemical etching the Group III Nitride face that is exposed by the two-dimensional array of mask features that are spaced apart from one another
Data Source
AI summary
An LED includes a mesa having a Group III Nitride mesa face and a mesa sidewall, on an underlying LED structure. The mesa face includes Group III Nitride surface features having tops that are defined by mask features, having bottoms, and having sides that extend along crystal planes of the Group III Nitride. The mask features may include a two-dimensional array of dots that are spaced apart from one another. Related fabrication methods are also disclosed.