LED Contact Layout for Uniform Edge Brightness
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Solution Overview
Problem
Existing optoelectronic devices face challenges such as non-uniform light emission and increased far field divergence angle due to current crowding near the edge, leading to unsatisfactory near-field uniformity and brightness disparities.
Innovation Solution
The optoelectronic device incorporates a conductive structure with varying contact lengths and widths to distribute current more uniformly, enhancing brightness uniformity and reducing far field divergence by using transparent conductive layers that partially block emission light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light emitting units are arranged with uniform contact lengths, then manufacturing is simpler, but current distribution becomes non-uniform causing brightness disparities
Solution Approach 1:
The patent applies local quality by varying the contact length of conductive structures based on their radial position. Light emitting units closer to the periphery have longer contact lengths than those in the central region. This non-uniform local configuration compensates for current crowding effects, achieving uniform current distribution and brightness across the entire array while maintaining manufacturability through a systematic design rule.
2Illumination intensity
If light emitting units are arranged with varying contact lengths to improve current distribution, then brightness uniformity improves, but device complexity increases
Solution Approach 1:
The patent changes the geometric parameter of contact length systematically based on radial position. By defining contact length as a function of distance from the central region, the design achieves uniform current distribution without requiring complex multi-layer conductive structures. The complexity is managed through a single parameter variation rule that can be applied during manufacturing.
3Illumination intensity
If transparent conductive layers are added to block emission light, then brightness uniformity improves, but light transmission efficiency decreases
Solution Approach 1:
The patent applies local quality by selectively placing transparent conductive layers only on light emitting units in the periphery region, not on central region units. This localized approach blocks excess light from units that would otherwise be over-bright due to current crowding, while preserving full light transmission from central units. The result is uniform brightness without sacrificing overall light transmission efficiency.
Data Source
AI summary
The present disclosure provides an optoelectronic device. The device includes: a substrate having a periphery; and a semiconductor stack disposed on the substrate. The semiconductor stack includes a first light emitting unit, and a second light emitting unit located closer to the periphery than the first light emitting unit to the periphery. The first light emitting unit includes a first light emitting stack and a first conductive structure directly contacting the first light emitting stack with a first contact length, and the second light emitting unit includes a second light emitting stack and a second conductive structure directly contacting the second light emitting stack with a second contact length. The second contact length is larger than the first contact length.