Light Emitting Element Electrode Structure for Current Uniformity
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Solution Overview
Problem
Conventional semiconductor light emitting elements experience uneven electric current distribution, leading to excessive heat generation, decreased carrier injection efficiency, and reduced quantum efficiency, especially under high current operations, due to the design of surrounding electrodes which can cause current crowding and heat accumulation.
Innovation Solution
A semiconductor light emitting element with a unique electrode structure where the electrode extending portions are arranged symmetrically and linearly, with a wider outer region for heat dissipation, and an offset arrangement of electrodes to prevent current crowding, allowing for efficient heat transfer and uniform current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surrounding electrode is disposed closely to the edge of the element to increase the electrode structure area, then the series resistance is reduced and current uniformity is improved, but current crowding occurs at the bent portions of the electrode extending portions leading to uneven current distribution
Solution Approach 1:
Instead of extending the electrode along the periphery to the edges (conventional approach), the patent inverts the approach by disposing the surrounding electrode at a specific distance from the end edges. This inversion prevents the electrode from reaching the edges where current crowding would occur, while still maintaining sufficient electrode area for low series resistance through optimized positioning and width.
Solution Approach 2:
The patent changes the parameters of the electrode structure by defining specific relationships between the width of the surrounding electrode, its distance from the end edges, and the width of the light emitting region. These parameter optimizations ensure uniform current distribution while preventing current crowding at bent portions.
2Reliability
If the surrounding electrode length is increased to improve current distribution, then current uniformity is enhanced, but heat dissipation becomes insufficient leading to excessive heat accumulation
Solution Approach 1:
The patent optimizes the parameters of the electrode structure, specifically the width of the surrounding electrode and its distance from the end edges, to achieve a balance between current uniformity and heat dissipation. The optimized parameters ensure sufficient electrode area for current distribution while maintaining adequate spacing for heat dissipation.
Solution Approach 2:
The patent applies different structural characteristics to different regions: the surrounding electrode provides current distribution in the peripheral region, while the light emitting region maintains adequate width for heat dissipation. This local differentiation resolves the contradiction between current uniformity and heat management.
3Reliability
If the electrode extending portion is bent to divide the area into compartments for uniform current spread, then current distribution is improved, but current crowding occurs at the bent portions causing local unevenness
Solution Approach 1:
The patent extracts the problematic bent portions from the electrode structure by disposing the surrounding electrode as a straight line at a specific distance from the end edges, eliminating the bent portions that cause current crowding while maintaining the current distribution function through optimized electrode positioning and width.
Solution Approach 2:
Instead of using bent electrode extending portions to divide the area (conventional approach), the patent inverts the approach by using a straight surrounding electrode at an optimized distance from the edges, achieving current distribution without the harmful bent portions.
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 solution achieves improved heat dissipation and uniform electric current distribution, enhancing the light emitting element's efficiency and reliability even under high current operations, while preventing excessive temperature rise and maintaining high output power.
Implementation Method 1
an electrode extending portion extending from a connection portion with an external electrode is formed along a periphery of an electrode forming surface for spreading electric current supplied to the both semiconductor layers on the entire surface of the semiconductor surfaces
Implementation Method 2
a light emitting element having a p-type semiconductor layer and a n-type semiconductor layer stacked interposing a light emitting layer
Implementation Method 3
the region surrounded by the electrode extending portion is further divided into a plurality of small regions by the electrode extending portion to uniformly spread the current in each region
Data Source
AI summary
The light emitting element includes a first electrode and a second electrode opposite each other and electrically connected respectively to a first conductive-type layer and a second conductive type layer constituting a semiconductor structure. The first electrode has a pair of electrode extending portions disposed opposite each other on an electrode forming surface over the first conductive-type layer which is positioned at the light extracting side. In the opposing direction of the pair of electrode extending portions, a half distance I1 between the electrode extending portions is smaller than the distance L2 from the electrode extending portions to an end edge of the electrode forming surface.