Vertical LED Transparent Layer Patterning for UV Emission
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Solution Overview
Problem
Existing vertical-type LEDs have limited light radiation angles and low ultraviolet emission efficiency due to the absorption of ultraviolet rays by traditional electrode materials like ITO and the narrow radiation angle of flat p-electrodes.
Innovation Solution
A method for manufacturing vertical-type LEDs and ultraviolet LEDs involving the formation of a transparent material layer with a different refractive index on the p-type clad layer, followed by patterning and the deposition of a reflective metal electrode layer to increase reflectance and radiation angles, and a p-electrode with a reduced area coverage to enhance ultraviolet emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat p-electrode is used to reflect light, then the electrode structure is simple, but the radiation angle is narrow
Solution Approach 1:
The patent applies curvature by forming a transparent material layer with a convex pattern (semicircular or arc-shaped) on the p-type clad layer. This curved surface structure reflects light in multiple directions, widening the radiation angle from the narrow vertical direction to a broader angular range, while maintaining structural simplicity
Solution Approach 2:
The patent transitions from a two-dimensional flat electrode surface to a three-dimensional convex patterned surface by adding height dimension through the transparent material layer. This dimensional change enables light to be reflected not only vertically but also at oblique angles, achieving wide radiation angle without complex multi-layer structures
2Reliability
If a transparent electrode layer like ITO is used, then current spreading is excellent, but ultraviolet ray transmission is reduced due to absorption
Solution Approach 1:
The patent segments the electrode function by separating the current spreading function (performed by the patterned transparent material layer) from the ultraviolet transmission function (performed by the open spaces between patterns). This segmentation allows the transparent material to provide current spreading while the patterned structure with gaps enables ultraviolet transmission by reducing the total absorbing material in the light path
Solution Approach 2:
The patent applies local quality by creating a patterned structure where the transparent material is present only in specific locations (convex patterns) rather than uniformly covering the entire surface. This localized presence provides current spreading where needed while leaving other areas open for ultraviolet transmission, thus reducing overall ultraviolet absorption
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 approach improves light reflectance and radiation angles for vertical-type LEDs and increases ultraviolet emission efficiency by minimizing absorption and optimizing the p-electrode's area coverage, resulting in higher light extraction efficiency and cost-effective manufacturing.
Implementation Method 1
forming a transparent material layer having a refractive index different from that of a p-type clad layer on the p-type clad layer
Implementation Method 2
forming a reflective metal electrode layer as a p-electrode on the transparent material layer to improve reflectance of light
Data Source
AI summary
A vertical type light emitting diode includes a nitride semiconductor having a p-n conjunction structure with a transparent material layer formed on a p type clad layer, the transparent material layer having a refractive index different from that of the p type clad layer and having a pattern structure of mesh, punched plate, or one-dimensional grid form, etc. A reflective metal electrode layer is formed on the transparent material layer as a p-electrode. A stereoscopic pattern is formed in the transparent material layer and the p-electrode deposited, and thereby forming the pattern in the p-electrode. Depositing the p-electrode on only 10 to 70% of the upper portion of the p type clad layer in an ultraviolet ray light emitting diode such that an area where the p type clad layer is exposed is wide increases the transmittance of ultraviolet rays through an area where the p-electrode is not deposited.