Patterned Sapphire Substrate for GaN LED Dislocation Reduction
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Solution Overview
Problem
Current methods for growing high-quality GaN-based LEDs on sapphire substrates face challenges such as high dislocation density, limited light-extraction efficiency, and high manufacturing costs, due to difficulties in forming patterned sapphire substrates and the use of two-step growth methods.
Innovation Solution
A novel substrate with a semiconductor dielectric layer and periodically arranged protrusions is used, allowing for selective growth and improved light reflection and scattering, reducing dislocation density and enhancing luminescent efficiency, while eliminating the need for the two-step growth method and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-step growth method is used to grow GaN epitaxial layer on sapphire substrate, then the crystalline quality is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-forming a patterned sapphire substrate with micropit structures before epitaxial growth. The sapphire substrate is etched with periodic micropits that serve as nucleation sites, preparing the substrate in advance to control the growth mode and reduce dislocation density during subsequent single-step MOCVD growth of GaN layers.
2Manufacturing precision
If conventional patterned sapphire substrate technology is used, then dislocation density is reduced, but the manufacturing cost and difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the sapphire substrate surface into periodic micropit structures. These segmented micropits are arranged in a regular pattern and serve as discrete nucleation sites for GaN growth, enabling controlled epitaxial growth with reduced dislocation density while simplifying the overall manufacturing process.
3Manufacturing precision
If higher growth temperature is used to grow high quality GaN layer, then the crystal quality improves, but the manufacturing time and energy consumption increase
Solution Approach 1:
The patent applies parameter changes by optimizing the relationship between growth temperature and time. By using patterned sapphire substrate with micropits, the process enables high-quality GaN growth at elevated temperatures while reducing the required growth time, as the pre-formed micropit structures facilitate faster nucleation and growth kinetics.
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 solution results in improved crystalline quality and luminous efficiency of GaN-based LEDs, with reduced production costs and increased production capacity, making it suitable for industrial-scale production.
Implementation Method 1
a buffer layer for growing a subsequent luminescent epitaxial structure
Implementation Method 2
there remains a certain area of (0001) crystal plane between the cone-shaped projections. Since there is a certain selective growth mechanism between the surface of the cone-shaped projections and the (0001) crystal plane between the cone-shaped projections
Implementation Method 3
improve light-extraction efficiency of the LED by diffuse scattering of the PPS patterns
Implementation Method 4
growing a device level GaN epitaxial layer by using a metal organic compound vapor deposition (MOCVD) method
Data Source
AI summary
A substrate used for III-V-nitride growth and a manufacturing method thereof, the manufacturing method including the following steps: 1) providing a growth substrate, and forming on the surface of the growth substrate a buffer layer used for subsequent growth of a luminescent epitaxial structure; 2) forming a semiconductor dielectric layer on the surface of the buffer layer; 3) by a photolithography process, etching a plurality of semiconductor dielectric protrusions arranged at intervals on the semiconductor dielectric layer, and exposing the buffer layer between the semiconductor dielectric protrusions. This method ensures the crystal quality of the grown luminescent epitaxial structure and also raises the luminescent efficiency of a light-emitting diode. The process is simple, advantageous for reducing cost of manufacture, and suitable for use in industrial production.