Semiconductor Light Emitting Device Reflective Electrode Structure
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in enhancing light extraction efficiency, particularly in large-sized products requiring high output and efficiency, where existing technologies fail to effectively reflect and direct light emitted from the active layer without absorption by electrodes.
Innovation Solution
The semiconductor light emitting device incorporates a reflective portion with a protrusion and a transparent electrode layer having an intaglio pattern, along with a current blocking layer and metal interface, to prevent contact and discoloration, enhancing light extraction efficiency by reflecting light away from the electrode areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflective portion is added to reflect light away from electrode areas, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The reflective portion is nested within the transparent electrode layer structure, with the reflective pad portion positioned at the bottom and the transparent electrode layer formed above it with openings that expose portions of the reflective surface. This nested configuration allows the reflective function to be integrated within the existing electrode architecture rather than adding a completely separate component.
Solution Approach 2:
The reflective portion extends in multiple dimensions - the reflective pad portion is disposed in a region of the upper surface of the second conductivity-type semiconductor layer, while the transparent electrode layer is formed above it with openings. This multi-dimensional arrangement allows light reflection to occur at different spatial levels, improving light extraction without requiring a completely separate planar structure.
2Productivity
If transparent electrode layer is formed over reflective portion, then light extraction efficiency is improved, but contact and discoloration issues arise
Solution Approach 1:
The transparent electrode layer is segmented into multiple regions through openings that expose portions of the reflective pad portion. This segmentation creates distinct functional zones: areas where the transparent electrode layer contacts the semiconductor layer for electrical connection, and areas where the reflective surface is exposed for light reflection. The openings are positioned to prevent direct contact between the transparent electrode layer and the reflective pad portion, thereby preventing discoloration while maintaining light extraction efficiency.
3Illumination intensity
If reflective portion structure is added, then light output is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The reflective pad portion is formed first on the upper surface of the second conductivity-type semiconductor layer before the transparent electrode layer is deposited. This preliminary formation of the reflective structure establishes a defined pattern that guides subsequent processing. The openings in the transparent electrode layer are then formed to expose specific portions of the reflective pad portion, with the pattern and positioning predetermined during the design stage, which helps manage manufacturing precision requirements.
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 increases light extraction efficiency by approximately 2% to 4% compared to comparative examples, with improved bonding strength and reduced delamination risks, leading to enhanced light output and efficiency in semiconductor light emitting devices.
Implementation Method 1
The second electrode includes a reflective pad portion disposed in a region of an upper surface of the second conductivity-type semiconductor layer
Implementation Method 2
a transparent electrode layer disposed on the second conductivity-type semiconductor layer and having an opening encompassing the reflective pad portion
Data Source
AI summary
A light emitting device includes a first semiconductor layer, an active layer, and a second semiconductor layer, and first and second electrodes electrically connected to the first and second semiconductor layers, respectively. The second electrode includes a reflective pad portion, a transparent electrode layer, a reflective finger portion and an electrode pad portion. The reflective pad portion is disposed in a region of an upper surface of the second semiconductor layer. The transparent electrode layer is disposed on the second semiconductor layer and has an opening encompassing the reflective pad portion such that the transparent electrode layer is not in contact with the reflective pad portion. The reflective finger portion extends from the reflective pad portion and has at least a portion thereof disposed on the transparent electrode layer. The electrode pad portion covers the reflective pad portion to be in contact with the transparent electrode layer.