Point Source LED Side Light Leakage Suppression
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Solution Overview
Problem
Point source light-emitting diodes suffer from side light leakage from their end faces, which interferes with light emission efficiency and can cause noise in measurements and communications, particularly due to the reflection of light rays by the metal reflection layer.
Innovation Solution
A point source light-emitting diode structure is designed with a metal reflection face localized under the active layer's light emission region and a light-reflection reduction face with lower reflectivity or higher absorptivity around the metal reflection face, along with a dielectric layer to inhibit diffusion and alloying, ensuring that light is directed towards the aperture and absorbed or diffused without reflection, thereby reducing side light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a metal reflection layer is provided all over the cross section to reflect light toward the topside electrode, then light-output efficiency is improved, but side light leakage from end faces increases causing noise
Solution Approach 1:
The patent applies local quality by providing the metal reflection layer only in a specific region beneath the light emission area rather than across the entire cross section. This localized approach reflects light toward the topside electrode aperture while preventing side light leakage from end faces, thus resolving the contradiction between improving light-output efficiency and reducing harmful side light effects.
Solution Approach 2:
The patent segments the reflection function by separating the metal reflection layer (for reflecting light toward the aperture) from the light-reflection reduction face (for absorbing or diffusing light toward end faces). This segmentation allows each region to perform its specific function independently, achieving both high light-output efficiency and minimal side light leakage.
2Measurement precision
If side walls are covered with wiring-cum-clad layer to suppress side light, then measurement precision may improve, but formation of uniform thickness side walls is difficult leading to manufacturing issues
Solution Approach 1:
The patent extracts the side light suppression function from the complex wiring-cum-clad layer structure and implements it through a dedicated light-reflection reduction face with specific optical properties (lower reflectivity and/or higher absorptivity). This simplifies the manufacturing process by eliminating the need to form uniform thickness side walls while still achieving effective side light suppression for improved measurement precision.
3Object-generated harmful factors
If a light-reflection reduction face is provided around the metal reflection face, then side light leakage is suppressed, but device structure becomes more complex
Solution Approach 1:
The patent merges the light-reflection reduction face with the existing chip structure, integrating it as part of the substrate or support layer rather than adding a completely separate component. This integration approach suppresses side light leakage while minimizing the increase in device complexity by utilizing the existing structural framework.
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 configuration effectively suppresses side light leakage from the end faces of the point source light-emitting diode, maintaining high light extraction efficiency while minimizing noise, with side light intensity reduced to around 4-5% without compromising output light intensity.
Implementation Method 1
the metal layer is provided locally in an area corresponding to the aperture and has a metal reflection face by which a light generated in the active layer is reflected towards the aperture side
Implementation Method 2
the present point source light-emitting diode further contains a light-reflection reduction face having a lower reflectivity and/or a higher absorptivity than the metal reflection face, provided around the metal reflection face
Data Source
AI summary
The present invention relates to a point source light-emitting diode containing a support substrate, a metal layer, a first conduction-type layer, an active layer, a second conduction-type layer containing a current-narrowing structure, and a topside electrode having an aperture, stacking in this order, in which the metal layer is provided locally in an area corresponding to the aperture and has a metal reflection face by which a light generated in the active layer is reflected towards the aperture side, and the point source light-emitting diode further contains a light-reflection reduction face having a lower reflectivity and/or a higher absorptivity than the metal reflection face, provided around the metal reflection face.