As-Cut Wafer Light Extraction via Epitaxial Roughness
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Solution Overview
Problem
Conventional light-emitting device manufacturing methods require costly and time-consuming polishing and patterning processes to achieve the necessary surface roughness for efficient light extraction, which increases production costs and complexity.
Innovation Solution
The method involves using an as-cut wafer with an irregularly uneven surface greater than 0.5 μm as a substrate for epitaxial growth of a light-emitting stack, eliminating the need for additional patterning or roughening processes, and achieving an upper surface roughness of less than 0.2 nm through epitaxial growth without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polishing and patterning processes are used to achieve necessary surface roughness for light extraction, then light extraction efficiency is improved, but production cost and manufacturing complexity increase
Solution Approach 1:
The as-cut wafer is provided with an irregularly uneven surface before epitaxial growth, which serves as a pre-prepared light scattering structure. This preliminary surface preparation eliminates the need for subsequent patterning or roughening processes, thereby reducing manufacturing complexity while maintaining light extraction efficiency
Solution Approach 2:
The as-cut wafer's inherent irregular surface structure automatically provides light scattering functionality without requiring additional processing steps. The natural surface irregularities of the as-cut wafer serve the dual purpose of substrate and light scattering element, making the system self-sufficient
2Illumination intensity
If polishing and patterning processes are used to achieve necessary surface roughness, then light extraction efficiency is improved, but production time and cost increase
Solution Approach 1:
The as-cut wafer is provided with an irregularly uneven surface before epitaxial growth, which serves as a pre-prepared light scattering structure. This preliminary surface preparation eliminates the need for subsequent patterning or roughening processes, thereby reducing manufacturing complexity while maintaining light extraction efficiency
Solution Approach 2:
The method skips the intermediate polishing and patterning steps that are traditionally required, moving directly from as-cut wafer provision to epitaxial growth. This omission of unnecessary steps accelerates production while maintaining the required light extraction performance
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 reduces production costs and simplifies the manufacturing process while maintaining effective light extraction and emission properties by utilizing the inherent irregularities of the as-cut wafer to scatter light from the light-emitting stack.
Implementation Method 1
utilizing the inherent irregularities of the as-cut wafer to scatter light from the light-emitting stack
Implementation Method 2
forming a light-emitting stack on the irregularly uneven surface of the as-cut wafer by an epitaxial growth method
Data Source
AI summary
A method for manufacturing a light-emitting device, comprises steps of: providing an as-cut wafer having an irregularly uneven surface comprising surface roughness greater than 0.5 μm; and forming a light-emitting stack on the irregularly uneven surface of the as-cut wafer by an epitaxial growth method, and the light-emitting stack comprises an upper surface having surface roughness less than 0.2 nm; wherein there is no patterning or roughing process after the step of providing the as-cut wafer and before the step of forming the light-emitting stack on the irregularly uneven surface of the as-cut wafer.