Semiconductor Light-Emitting Device Electrode Structure for Enhanced Light Extraction
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Solution Overview
Problem
In semiconductor light-emitting devices, the light reflecting effect of the second electrode is decreased, leading to reduced light extraction efficiency and luminance saturation, especially in minute devices, due to the absorption of reflected light by the nickel upper layer and the occurrence of migration, which affects current density and light-emitting intensity.
Innovation Solution
A semiconductor light-emitting device structure is developed with a transparent conductive material layer and an insulating layer, where the second electrode is formed on the transparent conductive material layer exposed at the bottom of an opening in the insulating layer, preventing direct contact with the light-emitting portion and ensuring the light is transmitted through the transparent layers, thus maintaining light reflection without absorption and reducing migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second electrode is formed as a reflecting electrode with an upper layer of nickel covering the lower layer of silver, then oxidation prevention and migration prevention are improved, but light absorption increases and light extraction efficiency decreases
Solution Approach 1:
The second electrode is segmented into two distinct parts: a lower reflecting layer (silver) and an upper protective layer (nickel). The reflecting layer is positioned to face the light-emitting portion while the protective layer covers the reflecting layer, creating a functional division that separates light reflection and oxidation prevention roles.
Solution Approach 2:
Different regions of the second electrode have different properties: the lower layer has high light reflectance while the upper layer has oxidation resistance. The upper layer selectively covers the lower layer in specific areas, creating local quality differences that optimize both light reflection and protection functions simultaneously.
2Reliability
If the upper layer protrudes beyond the lower layer edge, then oxidation prevention is improved, but light absorption increases and light extraction efficiency decreases
Solution Approach 1:
The upper layer is designed to protrude locally beyond the lower layer edge in specific regions, creating local quality differences. This selective protrusion provides oxidation prevention at the edges while maintaining light reflection in the central area, optimizing both protection and light extraction functions.
3Productivity
If the device size is reduced to minute dimensions, then device integration is improved, but the proportion of light-absorbing regions increases and light extraction efficiency decreases
Solution Approach 1:
The second electrode is segmented into functional zones: a central reflecting region and peripheral protective regions. This segmentation allows the light reflection function to be concentrated in the central area while protection is provided at the edges, maintaining high light extraction efficiency even in minute devices.
Solution Approach 2:
Different regions of the electrode structure have optimized properties for their specific functions: the central region maximizes light reflection while peripheral regions provide protection. This local quality optimization ensures that even when device size is reduced, the light extraction efficiency is maintained by preventing the light-absorbing regions from dominating the structure.
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 light extraction efficiency and prevents luminance saturation, maintaining high light-emitting intensity by ensuring the light reflecting effect is preserved and migration is minimized, allowing for more efficient semiconductor light-emitting devices with improved manufacturing efficiency and reduced costs.
Implementation Method 1
ensuring the light is transmitted through the transparent layers, thus maintaining light reflection without absorption
Implementation Method 2
a second electrode that reflects light from the light-emitting portion, the second electrode being formed on the transparent conductive material layer exposed at a bottom of the opening
Data Source
AI summary
A semiconductor light-emitting device includes (A) a light-emitting portion obtained by laminating in sequence a first compound semiconductor layer, an active layer, and a second compound semiconductor layer; (B) a first electrode electrically connected to the first compound semiconductor layer; (C) a transparent conductive material layer formed on the second compound semiconductor layer; (D) an insulating layer composed of a transparent insulating material and having an opening, the insulating layer being formed on the transparent conductive material layer; and (E) a second electrode that reflects light from the light-emitting portion, the second electrode being formed on the transparent conductive material layer and on the insulating layer in a continuous manner, wherein, assuming that areas of the active layer, the transparent conductive material layer, the insulating layer, and the second electrode are respectively S1, S2, S3, and S4, S1≦S2<S3 and S2<S4 are satisfied.