Semiconductor Light Emitting Apparatus Reflective Electrode Design
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Solution Overview
Problem
Existing semiconductor light emitting apparatuses face challenges in enhancing light extracting efficiency due to suboptimal electrode structures, which affect the reflection and distribution of light emitted from the semiconductor layers.
Innovation Solution
The semiconductor light emitting apparatus incorporates a light reflective electrode layer that overlaps with the second electrode at the peripheral portion, specifically forming a highly reflective n-side layer that overlaps with the p-side electrode, enhancing light reflection and reducing color unevenness by limiting the extent of the n-side highly reflective layer and using a n-side cap layer with higher light absorbing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional electrode structure is used, then the device complexity is reduced, but the light extracting efficiency deteriorates
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a first electrode, a light reflective electrode layer, and a second electrode. This segmentation allows each layer to perform its specific function (conduction, light reflection, and additional conduction/control) optimally, thereby improving light extracting efficiency while managing complexity through functional decomposition
Solution Approach 2:
The light reflective electrode layer serves multiple functions: it reflects light back into the semiconductor layer to improve extraction efficiency, provides electrical conduction, and contributes to the overall electrode functionality. This multi-functionality improves productivity without proportionally increasing device complexity
2Illumination intensity
If the n-side highly reflective layer is extended broadly, then light reflection is improved, but color unevenness increases
Solution Approach 1:
The n-side highly reflective layer is strategically positioned only at the peripheral portion where it overlaps with the p-side electrode, rather than being uniformly distributed. This local placement provides targeted light reflection where needed while avoiding excessive reflection that would cause color unevenness in other regions
Solution Approach 2:
Instead of applying reflective coverage uniformly across the entire electrode area, the invention uses partial action by limiting the reflective layer to specific peripheral regions. This partial coverage is sufficient to improve light extraction without creating the color unevenness that would result from excessive or uniform reflection across the entire surface
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 configuration significantly improves light extracting efficiency by effectively reflecting light back into the n-type semiconductor layer, preventing color unevenness and enhancing the overall performance of the light emitting apparatus.
Implementation Method 1
a light reflective electrode layer overlapping the second electrode at a peripheral portion... effectively reflecting light back into the n-type semiconductor layer
Implementation Method 2
using a n-side cap layer with higher light absorbing properties... preventing color unevenness
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A semiconductor light emitting apparatus includes semiconductor lamination of n-type layer, active layer, and p-type layer; recess penetrating the lamination from the p-type layer and exposing the n-type layer; n-side electrode formed on the n-type layer at the bottom of the recess and extending upward above the p-type layer; a p-side electrode formed on the p-type layer and having an opening surrounding the recess in plan view, the n-side electrode extending from inside to above the recess; and an insulating layer disposed between the p-side and the n-side electrodes on the p-type layer, the p-side electrode constituting a reflective electrode reflecting light incident from the active layer, the n-side electrode including a reflective electrode layer covering the opening in plan view and reflects light incident from the emission layer side, the reflective electrode layer having peripheral portion overlapping peripheral portion of the p-side electrode in plan view.