Semiconductor Light-Emitting Element Electrode Reflectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor light-emitting elements for deep ultraviolet light face challenges in achieving high light extraction efficiency due to low reflectivity of p-side electrodes, which leads to absorption of light and increased contact resistance when openings are formed for reflection electrodes.
Innovation Solution
The design includes a p-side contact electrode with a larger area than the n-side contact electrode, both having high reflectivity, with specific materials and configurations to ensure a reflectivity of 50% or higher across the substrate, reducing absorption losses and improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an opening is formed on the p-type clad layer for the reflection electrode, then the light extraction efficiency is improved, but the contact area of the p-side electrode is reduced resulting in increased contact resistance
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a reflection electrode layer (Al or Ag) for high reflectivity, and a separate p-side electrode layer (Ni/Au) for electrical contact. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between light extraction efficiency and contact resistance.
Solution Approach 2:
The electrode structure uses composite material stacking with Al/Ag providing high reflectivity for deep ultraviolet light (reflectivity ≥90%) and Ni/Au providing low contact resistance. This composite structure achieves both high light extraction efficiency and low contact resistance simultaneously.
2Productivity
If the p-side electrode material is changed to achieve high reflectivity, then the light extraction efficiency is improved, but the contact resistance may increase
Solution Approach 1:
The electrode is divided into distinct functional segments: the reflection electrode layer (Al or Ag) handles light reflection with ≥90% reflectivity, while the p-side electrode layer (Ni/Au) handles electrical conduction with low contact resistance. This functional segmentation resolves the material property contradiction.
Solution Approach 2:
The electrode structure employs composite material stacking where Al or Ag layers provide high reflectivity for deep ultraviolet light, and Ni/Au layers provide excellent electrical conductivity and low contact resistance. The composite structure achieves both optical and electrical performance requirements.
3Reliability
If the area of the p-side contact electrode is increased to reduce contact resistance, then the contact resistance is reduced, but the area for the active layer is reduced
Solution Approach 1:
The electrode structure is segmented into a reflection electrode layer for optical function and a p-side electrode layer for electrical function. This allows the electrical contact layer to be optimized for low resistance without compromising active layer area, as the optical function is handled by the separate reflection layer.
Solution Approach 2:
The composite electrode structure with Al/Ag and Ni/Au layers enables independent optimization of optical reflectivity and electrical conductivity. The Ni/Au layer can be designed with sufficient area for low contact resistance while the Al/Ag layer provides the required optical reflection, resolving the area trade-off contradiction.
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 enhances light emission efficiency by increasing the active layer area and reducing contact resistance, achieving a reflection efficiency of 50% or higher, thereby improving the overall light extraction efficiency of the semiconductor light-emitting element.
Implementation Method 1
a reflectivity of the p-side contact electrode for ultraviolet having a wavelength of 280 nm incident from a side of the p-type semiconductor layer as R1, and a reflectivity of the n-side contact electrode for ultraviolet light having a wavelength of 280 nm incident from a side of the n-type semiconductor layer as R2
Data Source
AI summary
A semiconductor light-emitting element is configured to emit ultraviolet light having a wavelength of 320 nm or shorter. Denoting a total area of a principal surface of a substrate as S0, an area on a p-type semiconductor layer in which a p-side contact electrode is formed as S1, an area on an n-type semiconductor layer in which an n-side contact electrode is formed as S2, a reflectivity of the p-side contact electrode for ultraviolet having a wavelength of 280 nm incident from a side of the p-type semiconductor layer as R1, and a reflectivity of the n-side contact electrode for ultraviolet light having a wavelength of 280 nm incident from a side of the n-type semiconductor layer as R2, (S1/S0)×R1+(S2/S0)×R2≥0.5, S1>S2, and R1≤R2.