Nitride Semiconductor Light Emitting Device with Inclined Surface Texture
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Solution Overview
Problem
Current semiconductor light emitting devices struggle to achieve a simplified manufacturing process for white light emission with good color rendering and a wavelength range equivalent to or near the visible light range, as existing methods are complex and involve phosphor use or intricate substrate structures.
Innovation Solution
A nitride semiconductor light emitting device is manufactured using a sapphire substrate with a specific lamination structure and surface texture patterned with inclined angles, allowing for broad light emission wavelengths through a multiple quantum well layer and varying inclination angles in the active layer, enabling near-white light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor-containing resin is used to seal a package mounting a blue LED to generate white light, then white light emission is achieved, but the manufacturing process becomes complex and the structure is not simplified
Solution Approach 1:
The invention extracts and eliminates the phosphor-containing resin package structure, replacing it with a direct nitride semiconductor light emitting device that generates white light through its active layer. This removes the need for separate phosphor mixing, coating, and curing processes, thereby simplifying the manufacturing process while maintaining white light emission capability.
Solution Approach 2:
The nitride semiconductor active layer serves multiple functions: it generates blue light directly and simultaneously generates yellow light through internal phosphorescence, combining the functions of a blue LED and a phosphor converter into a single component. This multi-functionality eliminates the need for separate phosphor materials and simplifies the overall device structure.
2Illumination intensity
If monochromatic LED's are mounted in a package to obtain white light, then white light emission is achieved, but the mounting process becomes complicated
Solution Approach 1:
The invention merges multiple light-emitting functions into a single nitride semiconductor device. The active layer simultaneously emits blue light and generates yellow light through internal phosphorescence, which combines to form white light. This consolidation eliminates the need for mounting multiple monochromatic LEDs and assembling them into a package, significantly simplifying the manufacturing process.
3Illumination intensity
If indium is added in light emitting layer in varied composition to broaden light emission wavelength range, then near-white light emission is achieved, but the composition control and manufacturing precision requirements increase
Solution Approach 1:
The invention utilizes parameter changes in the nitride semiconductor composition, specifically varying the indium content in the InGaN alloy within a controlled range (5-30 atomic%). By optimizing the indium composition and controlling the quantum well structure, the device achieves broad wavelength emission from blue to yellow without requiring extremely precise composition control, as the internal phosphorescence mechanism naturally broadens the emission spectrum.
4Illumination intensity
If a V groove is formed and GaNAs or GaNP active layer is grown thereon to emit light having a plurality of wavelengths, then near-white light is generated through color mixture, but the device structure and manufacturing process become more complex
Solution Approach 1:
Instead of forming V grooves and growing complex multi-layer structures to achieve multi-wavelength emission, the invention inverts the approach by using a planar nitride semiconductor structure with an optimized InGaN active layer that naturally emits across a broad wavelength range through quantum well confinement and internal phosphorescence. This simplifies the device structure while achieving the same multi-wavelength emission effect.
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 device achieves a wide light emission wavelength range (440 nm to 640 nm) with improved color rendering, simplifying the manufacturing process and enhancing light emission characteristics compared to reference samples.
Implementation Method 1
a light emitting layer... emit light having different wavelengths, enabling generation of near-white light through color mixture
Implementation Method 2
a light emitting layer... emit light having different wavelengths, enabling generation of near-white light through color mixture
Implementation Method 3
A crystal growth layer is formed in the substrate surface wherein at least a portion of which is oriented along an inclined plane with respect to a principal plane of the substrate
Implementation Method 4
A crystal growth layer is formed in the substrate surface wherein at least a portion of which is oriented along an inclined plane with respect to a principal plane of the substrate
Data Source
Figure 1A~1F
Figure 2A~2B
Figure 3
AI summary
A nitride semiconductor light emitting device is formed by: forming a resist pattern (3p) on a first nitride semiconductor layer (2) formed on a substrate (1), the resist pattern having a region whose inclination angle relative to a substrate surface changes smoothly as viewed in a cross section perpendicular to the substrate surface; etching the substrate by using the resist pattern as a mask to transfer the resist pattern to the first nitride semiconductor layer; and forming an light emitting layer on the patterned first nitride semiconductor layer. The nitride semiconductor light emitting device can emit near-white light or have a wavelength range generally equivalent to or near visible light range.