Semiconductor Light Emitting Device Trench Electrode Design
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Solution Overview
Problem
Existing semiconductor light emitting devices face challenges in maintaining mechanical strength and reliability due to current concentration on n-type electrodes and difficulty in controlling light emission efficiency and chromatic uniformity, which increases chip size and costs.
Innovation Solution
A semiconductor light emitting device structure where the n-type contact layer is partly etched to expose the n-type contact layer adjacent to the light emitting layer, with both n-type and p-type electrodes formed on separate surfaces, and a trench formed in the first semiconductor layer to increase the contact area of the n-type electrode without altering the chip size, along with a phosphor layer for wavelength conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the n-type electrode contact area is increased to reduce current concentration, then the reliability is improved, but the chip size increases
Solution Approach 1:
The patent transitions from a planar electrode configuration to a three-dimensional structure by forming the n-type electrode on the side surface of the trench. This vertical dimensionality change allows the electrode contact area to be increased without expanding the chip's planar footprint, thereby improving current distribution and reliability while maintaining compact chip size.
Solution Approach 2:
The n-type electrode is nested within the trench structure, utilizing the vertical space created by the etched trench. This nesting approach allows the electrode to access the light-emitting layer through the trench while being contained within the chip's overall boundary, effectively increasing contact area without increasing chip dimensions.
2Reliability
If the light emitting layer area is reduced to improve chromatic uniformity, then the chromatic uniformity is improved, but the brightness decreases
Solution Approach 1:
The patent applies local quality by creating a trench with specific dimensional characteristics (depth and width) that concentrates the light emission in a localized region. The trench structure provides a controlled environment for light generation, ensuring uniform chromatic properties in the active region while the overall chip area can be optimized for brightness through the enhanced current distribution provided by the side-surface electrode.
3Reliability
If a trench is formed to increase n-type electrode contact area, then the current distribution is improved, but the device complexity increases
Solution Approach 1:
The patent segments the electrode configuration into distinct components: a planar n-type electrode on the first surface and a side-surface n-type electrode on the trench wall. This segmentation allows each electrode component to serve a specific function in current distribution, with the trench providing a structured pathway that organizes the current flow paths and simplifies the overall electrical architecture.
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 structure enhances the reliability and brightness of the device by distributing the electric field, reduces the load on the phosphor layer and lens design, and allows for downsizing and cost reduction while maintaining mechanical strength through the use of metal pillars and resin.
Implementation Method 1
a phosphor layer (27), which are formed collectively in a wafer state
Data Source
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AI summary
According to one embodiment, a semiconductor light emitting device includes, a first semiconductor layer, a second semiconductor layer, a first electrode, a second electrode, a first interconnection, and a second interconnection. The first semiconductor layer has a first major surface, a second major surface provided on an opposite side to the first major surface, a protrusion selectively provided on the second major surface, and a trench formed from the second major surface to the first major surface. The second semiconductor layer is stacked on the protrusion of the first semiconductor layer and includes a light emitting layer. The first electrode is provided on the second major surface of the first semiconductor layer and a side surface of the trench. The second electrode is provided on a surface of the second semiconductor layer on an opposite side to the first semiconductor layer