Semiconductor Light-Emitting Device Side Surface Phosphor Integration
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Solution Overview
Problem
Conventional wavelength-converting light-emitting diodes struggle to produce white light effectively due to bluish light emission from side surfaces, as the light emitted from these surfaces does not pass through the phosphor layer, leading to incomplete wavelength conversion.
Innovation Solution
A semiconductor light-emitting device is designed with a light-blocking member on its side surfaces and a phosphor layer on the main surface, where the light-blocking member is made of the same metal as the interconnects and is opaque to light emitted from the light-emitting layer, ensuring that light is directed towards the phosphor layer for wavelength conversion, thereby preventing leakage and enhancing brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor layer is formed on the upper surface of a wafer including numerous LEDs, then wavelength conversion can be achieved, but bluish light is emitted from the side surface because light from the side surface does not pass through the phosphor layer
Solution Approach 1:
The patent applies this principle by converting the harmful bluish light emitted from side surfaces into beneficial yellow light through wavelength conversion. A phosphor layer containing yellow phosphor is formed on the side surfaces of the semiconductor layer, transforming the unwanted blue light into yellow light that contributes to white light emission, thereby eliminating the harmful effect while maintaining device structure.
Solution Approach 2:
The patent extends the phosphor layer application from the traditional upper surface only to include the side surfaces of the semiconductor layer. This dimensional expansion ensures that light emitted from all directions (including side surfaces) passes through phosphor material, enabling comprehensive wavelength conversion and eliminating bluish light emission from previously unaffected side surfaces.
2Illumination intensity
If the side surface light is blocked to prevent bluish emission, then white light quality improves, but light loss increases and brightness decreases
Solution Approach 1:
Instead of blocking the side surface light which would cause energy loss, the patent converts the bluish light into yellow light using a phosphor layer on the side surfaces. This transformation maintains the light output while improving color quality, thereby eliminating the trade-off between white light quality and brightness by turning the previously harmful blue light into a beneficial component of white light.
3Illumination intensity
If a light-blocking member is added to block side surface light, then wavelength conversion completeness improves, but device complexity increases
Solution Approach 1:
The patent merges the light-blocking function with the wavelength conversion function by integrating a phosphor layer on the side surfaces. This single structure simultaneously blocks direct blue light emission and converts it to yellow light, eliminating the need for separate light-blocking members and reducing device complexity while achieving complete wavelength conversion.
Solution Approach 2:
The phosphor layer on side surfaces serves multiple functions: it acts as a wavelength converter transforming blue light to yellow light, and simultaneously functions as a light-blocking layer preventing direct blue light emission. This multi-functionality eliminates the need for additional components, reducing structural complexity while achieving complete wavelength conversion.
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 allows for the production of white light with a desired tint by ensuring that light from the light-emitting layer is converted by the phosphor layer, reducing bluish light emission and maintaining brightness, thus overcoming the limitations of existing technologies.
Implementation Method 1
a wavelength-converting light-emitting diode, which a blue light-emitting element is combined with a phosphor to produce white light
Implementation Method 2
a light-blocking member provided on a side surface of the semiconductor layer and being opaque to light emitted from the light-emitting layer
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3C
AI summary
A semiconductor light-emitting device of the invention includes: a semiconductor layer (15) including a light-emitting layer and having a first major surface (12) and a second major surface opposite to the first major surface (12); a phosphor layer (61) facing to the first major surface (12); an interconnect layer provided on the second major surface side and including a conductor (16,17,41,42) and an insulator (21,22); and a light-blocking member (35,51,36,39) provided on a side surface of the semiconductor layer (15) and being opaque to light emitted from the light-emitting layer.