Semiconductor Light Emitting Device With Intermediate Separation Layer
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Solution Overview
Problem
Semiconductor light emitting devices face challenges in maintaining high luminance efficiency due to increased current density and heating, which can be exacerbated by the reduction in effective light emitting area during the isolation process for forming multiple LED cells.
Innovation Solution
Incorporating an intermediate separation layer with an energy band gap equal to or greater than the first conductivity-type semiconductor layer, which allows for electrical separation and reduces the depth of the isolation groove, thereby preserving the effective light emitting area and enhancing luminance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the area of LED chip is increased to reduce current density, then current density is reduced, but it becomes difficult to implement uniform current density across the entire chip area and high production yield becomes difficult to obtain
Solution Approach 1:
The LED chip is divided into multiple LED cells through the isolation process, with each cell having its own light emitting area. This segmentation allows for better current distribution while maintaining manageable chip areas that can be manufactured with high yield
Solution Approach 2:
By creating multiple isolated LED cells with gentle slopes on their surfaces, the patent enables localized optimization of current distribution in each cell while maintaining uniformity across the entire chip through standardized cell structures
2Ease of manufacture
If a large amount of epitaxial layer is removed during isolation process to form LED cells, then LED cells can be formed, but effective light emitting area is drastically reduced
Solution Approach 1:
An intermediate separation layer is formed between the base semiconductor layer and the first conductivity-type semiconductor layer before the isolation process. This preliminary structure allows the isolation process to proceed more easily while preserving the effective light emitting area, as the separation occurs at the intermediate layer rather than requiring deep removal into the active layers
Solution Approach 2:
The intermediate separation layer acts as a mediator that facilitates the isolation process. It provides a convenient plane for separation that enables formation of LED cells with gentle slopes without requiring excessive removal of the epitaxial layer, thus preserving the light emitting area
3Ease of manufacture
If slopes of surfaces of LED cells are made gentle to allow metal deposition, then metal can be easily deposited, but large amount of epitaxial layer must be removed during isolation process
Solution Approach 1:
The intermediate separation layer is formed in advance to provide a predetermined separation plane. This allows the isolation process to create gentle slopes by separating at this intermediate level rather than requiring deep etching that would remove large amounts of epitaxial layer, thus enabling easy metal deposition while minimizing material loss
4Power
If rated current is increased to obtain high luminous flux, then luminous flux is increased, but current density increases and luminance efficiency degrades due to heating
Solution Approach 1:
By dividing the LED chip into multiple LED cells, the patent distributes the total current across multiple independent light emitting areas. This allows the device to achieve high luminous flux through increased current while maintaining lower current density in each individual cell, thereby reducing heating and preserving luminance efficiency
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 use of the intermediate separation layer minimizes the reduction in the effective light emitting area, leading to improved luminance efficiency and allowing for uniform current distribution across the LED cells, even when using a conductive substrate.
Implementation Method 1
an intermediate separation layer interposed between the base semiconductor layer and the first conductivity-type semiconductor layer in order to electrically separate the base semiconductor layer and the first conductivity-type semiconductor layer; The intermediate separation layer may be a material layer having an energy band gap equal to or greater than that of the first conductivity-type semiconductor layer
Data Source
AI summary
A semiconductor light emitting device includes a substrate, a semiconductor laminate having a base semiconductor layer, a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer sequentially formed on the substrate and divided by an isolation region to provide a plurality of light emitting cells, an intermediate separation layer interposed between the base semiconductor layer and the first conductivity-type semiconductor layer, a plurality of first and second electrodes connected to the first and second conductivity-type semiconductor layers, respectively, of the plurality of light emitting cells, and a wiring unit connecting the first and second electrodes of different light emitting cells.