LED with Carbon Nanotubes and Convex Sapphire Substrate
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) with sapphire substrates suffer from growth defects due to flat growing surfaces, resulting in low quality LEDs.
Innovation Solution
A light emitting diode design featuring a sapphire substrate with convex surfaces and carbon nanotubes, where the un-doped GaN layer grows along the convexities and carbon nanotubes, facilitating epitaxial growth and reducing defects, and the carbon nanotubes enhance current distribution by lowering electrical resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat sapphire substrate is used, then the manufacturing process is simple, but growth defects occur in the N-type semiconductor layer resulting in low LED quality
Solution Approach 1:
The patent applies curvature to the substrate surface by forming convexes on the sapphire substrate. This curved surface modifies the epitaxial growth of the N-type semiconductor layer, preventing growth defects that occur on flat surfaces while maintaining manufacturing feasibility through standard semiconductor processing techniques.
2Power
If carbon nanotubes are added to improve current distribution, then light-generating efficiency increases, but device structure becomes more complex
Solution Approach 1:
The patent applies local quality by strategically placing carbon nanotubes in specific regions where current distribution improvement is needed. Rather than uniformly distributing complex structures throughout the device, the carbon nanotubes are positioned to locally enhance electrical properties, improving light-generating efficiency while minimizing overall structural complexity.
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 design improves the growth quality of the N-type and active layers, reduces defects, and increases light-generating efficiency by facilitating better current distribution through the carbon nanotubes.
Implementation Method 1
the carbon nanotubes enhance current distribution by lowering electrical resistivity
Implementation Method 2
the un-doped GaN layer grows along the convexities and carbon nanotubes, facilitating epitaxial growth
Data Source
AI summary
A light emitting diode includes a substrate, an un-doped GaN layer, a plurality of carbon nanotubes, an N-type GaN layer, an active layer formed on the N-type GaN layer, and a P-type GaN layer formed on the active layer. The substrate includes a first surface and a second surface opposite and parallel to the first surface. A plurality of convexes is formed on the first surface of the substrate. The un-doped GaN layer is formed on the first surface of the substrate. The plurality of carbon nanotubes is formed on an upper surface of the un-doped GaN layer. The plurality of carbon nanotubes is spaced from each other to expose a portion of the upper surface of the un-doped GaN layer. The N-type GaN layer is formed on the exposed portion of the upper surface of the un-doped GaN layer and covering the carbon nanotubes therein.