Reflective Electrode Barrier Layer for Light Extraction
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Solution Overview
Problem
Conventional light-emitting diodes face efficiency degradation due to light absorption by electrodes and migration of mirror layer materials, which increases electrode resistance and reduces light-emitting efficiency, especially under high electrical currents.
Innovation Solution
A light-emitting device with a semiconductor stack, an electrode comprising a mirror layer, an adhesion layer, a bonding layer, and a barrier layer formed from multiple metal pairs to prevent material migration and reaction, enhancing light extraction and maintaining electrode conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is provided to prevent material migration, then electrode resistance increase is prevented, but the barrier layer is destroyed by high electrical current
Solution Approach 1:
The barrier layer is formed by combining two different metals (e.g., Ti and Mo, or W and Pt) to create a composite structure. This composite barrier layer provides both migration prevention and high-current resistance, as the different metals complement each other's properties to withstand electrical currents that would destroy single-metal barrier layers.
Solution Approach 2:
The barrier layer acts as an intermediary between the mirror layer and the bonding layer, preventing direct contact and reaction between these layers. The two-metal composition enhances this protective function under high current conditions, maintaining electrode conductivity without being destroyed.
2Illumination intensity
If the electrical current is increased to emit more light, then light output is improved, but the barrier layer is destroyed
Solution Approach 1:
The dual-metal barrier layer composition provides enhanced stability under high current conditions required for increased light output. The combination of two metals with different properties creates a more robust barrier that resists destruction even when high currents are applied to achieve higher illumination intensity.
3Device complexity
If a single metal barrier layer is used, then the structure is simple, but it cannot prevent material migration effectively under high current
Solution Approach 1:
The barrier layer transitions from a single metal to a composite of two different metals. This increases structural complexity but significantly improves the ability to prevent material migration under high current conditions, as each metal contributes different protective properties that complement each other.
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
The solution effectively prevents material migration and reaction, maintaining high light-emitting efficiency and electrode conductivity even under high electrical currents, extending the device's operational lifespan.
Implementation Method 1
a barrier layer inserted between the mirror layer and the bonding layer and covers the mirror layer to prevent the mirror layer reacting with the bonding layer
Implementation Method 2
the mirror layer under the electrode has been provided to solve the problem. When the route of the light extracted from the light-emitting layer is blocked by the electrode, the mirror can reflect but not absorbs the light
Implementation Method 3
an adhesion layer inserted between the mirror layer and the semiconductor light emitting stack
Data Source
AI summary
A light-emitting device includes a semiconductor light emitting stack; an electrode on the semiconductor light emitting stack, the electrode including a mirror layer, an adhesion layer inserted between the mirror layer and the semiconductor light emitting stack, a bonding layer; and a plurality of pits between the bonding layer and the semiconductor light emitting stack, wherein one of the plurality of pits is not filled up by the adhesion layer.