LED Current Uniformity via Localized Electrode Spacing
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Solution Overview
Problem
Light emitting elements experience uneven luminance distribution due to non-uniform current density in the active layer, despite uniform arrangement of n-type semiconductor layer exposed portions, as the current density remains non-uniform when p-side electrodes are arranged uniformly.
Innovation Solution
The arrangement of p-side electrodes is modified by placing exposed portions adjacent to the p-side electrode differently from the uniform arrangement of other exposed portions, with first exposed portions at equal intervals and second exposed portions closer to the p-side electrode, reducing current concentration and achieving more uniform current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If exposed portions are uniformly arranged across the light emitting region, then manufacturing simplicity is improved, but current density uniformity deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the arrangement of exposed portions into two groups: first exposed portions arranged uniformly in the light emitting region, and second exposed portions arranged non-uniformly near the p-side electrode. This local differentiation allows the region near the p-side electrode (where current concentration occurs) to have a different exposed portion arrangement than other regions, thereby achieving uniform current density while maintaining overall manufacturing simplicity.
2Device complexity
If p-side electrode is arranged at one corner, then device structure is simplified, but current density uniformity deteriorates
Solution Approach 1:
The patent simplifies the device structure by placing the p-side electrode at one corner of the light emitting region, while compensating for the resulting current density non-uniformity through localized adjustment of second exposed portions near the p-side electrode. This approach maintains structural simplicity while achieving current density uniformity through local optimization.
Data Source
AI summary
A light emitting element includes a semiconductor stacked layer body having an n-type semiconductor layer, an active layer, and a p-type semiconductor layer in this order, and a plurality of exposed portions defined at an upper surface side of the semiconductor stacked layer body, the plurality of exposed portions respectively exposing a part of the n-type semiconductor layer, a p-side electrode arranged in a first region and electrically connected with an upper surface of the p-type semiconductor layer and, arranged at one corner above the p-type semiconductor layer in a plan view, and an n-side electrode electrically integrally connected to the plurality of exposed portions and arranged in a different region in a plan view. In a plan view, the semiconductor stacked layer body has a rectangular shape and the plurality of exposed portions includes, a plurality of first exposed portions arranged at substantially equal intervals along a side of the semiconductor stacked layer body and a plurality of second exposed portions arranged closer to the p-side electrode than the first exposed portions are to the p-side electrode. The plurality of second exposed portions include at least one second exposed portion which has a shortest distance to the first exposed portions, the shortest distance to the first exposed portions being longer than a shortest distance among the first exposed portions. The at least one second exposed portion also has a shortest distance to the p-side electrode shorter than the shortest distance among the first exposed portions.