Nitride Semiconductor Template Manufacturing via Sapphire Nitridation
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Solution Overview
Problem
The challenge in manufacturing nitride semiconductor templates for solid-state light-emitting elements that emit ultraviolet light is the presence of defects and dislocations due to lattice constant differences between sapphire substrates and Group III nitride semiconductors, leading to suboptimal crystallinity and efficiency in light emission.
Innovation Solution
A method involving a sapphire substrate treated in a water vapor atmosphere to form a nitrided surface, followed by growing a nitride semiconductor layer with a high aluminum ratio using vapor-phase methods, which results in a template with high crystallinity and no cloudiness on the surface, suitable for face-down structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Group III nitride semiconductor layer is grown directly on a sapphire substrate, then the manufacturing process is simple, but many defects and dislocations appear due to large lattice constant difference
Solution Approach 1:
The sapphire substrate surface is pre-treated with water vapor before nitride semiconductor layer growth to form a modified surface layer. This preliminary action prepares the substrate surface to better match the lattice constant of the nitride semiconductor, reducing dislocations and defects in the grown layer while maintaining process simplicity.
Solution Approach 2:
The surface properties of the sapphire substrate are changed by exposing it to water vapor, which modifies the surface composition and structure. This parameter change in the substrate surface reduces the lattice mismatch with the nitride semiconductor layer, thereby improving crystallinity and reducing defects.
2Manufacturing precision
If a buffer layer is formed to reduce defects and dislocations, then crystallinity quality improves, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of forming a separate buffer layer, the sapphire substrate surface is pre-treated with water vapor to create a modified surface that directly supports high-quality nitride semiconductor growth. This eliminates the need for an additional buffer layer while achieving similar or better defect reduction.
Solution Approach 2:
The buffer layer function is extracted and integrated into the substrate surface treatment step. By modifying the sapphire substrate surface with water vapor, the substrate itself acquires the buffer-like properties needed to reduce dislocations, eliminating the separate buffer layer component.
3Strength
If aluminum nitride layer is grown on nitrided sapphire surface, then crack-free layer is achieved, but water vapor treatment is required
Solution Approach 1:
The sapphire substrate is pre-treated with water vapor to form a modified surface layer before growing the aluminum nitride film. This preliminary surface modification ensures excellent adhesion and lattice matching, resulting in a crack-free aluminum nitride layer without requiring additional process steps.
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 method produces a nitride semiconductor template with high crystallinity and no cloudiness, enabling efficient ultraviolet light emission in solid-state light-emitting elements, such as those used in germicidal lamps and lithography light sources.
Implementation Method 1
nitriding a surface of the base substrate by contacting the base substrate with a nitrogen raw material to form a nitrided area on the surface of the base substrate
Implementation Method 2
growing a nitride semiconductor layer on the nitrided area
Data Source
AI summary
A method of manufacturing a nitride semiconductor template that includes a base substrate of a sapphire substrate and a nitride semiconductor layer represented by a general formula AlxGa1-xN (0.3≦x≦1) includes: contacting the base substrate with a water vapor atmosphere, nitriding a surface of the base substrate by contacting the base substrate with a nitrogen raw material to form a nitrided area on the surface of the base substrate, and growing a nitride semiconductor layer on the nitrided area.