Group III Nitride Semiconductor Layer Light Extraction via Convex Substrate
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Solution Overview
Problem
The challenge is to produce a group III nitride semiconductor layer with excellent crystallinity for light-emitting devices, as forming a concavo-convex surface on the sapphire substrate can lead to crystal defects and reduced internal quantum efficiency due to the integration of semiconductor layers, affecting the LED structure's overall performance.
Innovation Solution
A method involving substrate processing to form convex parts on the C-plane of the sapphire substrate, followed by epitaxial growth of the group III nitride semiconductor layer to embed these convex parts, creating a concavo-convex interface that reduces light confinement and enhances light extraction efficiency while maintaining excellent crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a concavo-convex surface is formed on the sapphire substrate to improve light extraction efficiency, then light extraction efficiency is improved, but crystal defects occur and internal quantum efficiency is reduced
Solution Approach 1:
A buffer layer is formed on the sapphire substrate before forming the concavo-convex surface structure. This preliminary action prepares the substrate surface to support subsequent semiconductor layer growth while maintaining the desired concavo-convex morphology for light extraction, preventing crystal defects from forming during the epitaxial growth process
Solution Approach 2:
The buffer layer acts as an intermediary between the sapphire substrate and the group III nitride semiconductor layer. It mediates the interface between these two materials, allowing the concavo-convex surface to maintain its light extraction benefits while providing a suitable growth surface that prevents crystal defects in the semiconductor layer
2Loss of energy
If mechanical or chemical processing is used to form a concavo-convex surface, then light extraction efficiency is improved, but damage occurs in the light-emitting layer
Solution Approach 1:
The patent replaces mechanical or chemical processing methods with a deposition-based approach. A buffer layer is deposited and then selectively removed or patterned to form the concavo-convex surface, avoiding the mechanical stress and damage that would occur with traditional mechanical polishing or chemical etching methods
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 results in a group III nitride semiconductor layer with improved crystallinity and light extraction efficiency, reducing leakage current and enhancing the internal quantum efficiency of the light-emitting device, leading to higher output and better electrical characteristics.
Implementation Method 1
epitaxially growing the group III nitride semiconductor layer on the upper surface, to thereby embed the convex parts in the group III nitride semiconductor layer
Data Source
AI summary
The present invention is a method for producing a group III nitride semiconductor layer in which a single crystal group III nitride semiconductor layer (103) is formed on a substrate (101), the method including: a substrate processing step of forming, on the (0001) C-plane of the substrate (101), a plurality of convex parts (12) of surfaces (12c) not parallel to the C-plane, to thereby form, on the substrate, an upper surface (10) that is composed of the convex parts (12) and a flat surface (11) of the C-plane; and an epitaxial step of epitaxially growing the group III nitride semiconductor layer (103) on the upper surface (10), to thereby embed the convex parts (12) in the group III nitride semiconductor layer (103).