Ohmic Contact Structure for Nitride LEDs
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Solution Overview
Problem
Current light emitting devices, particularly nitride-based semiconductor LEDs, face challenges in achieving optimal electrical conductivity and stability due to issues with ohmic contacts, leading to reduced light emission efficiency and increased heat generation.
Innovation Solution
The development of a light emitting device with a specific ohmic contact structure involving layers of aluminum (Al) and copper (Cu) alloys, along with an interlayer to prevent oxidation, which enhances electrical conductivity and stability, and the use of a non-linear impedance region to reduce heat generation and improve light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ohmic contact structure is used, then the device structure is simple, but the electrical conductivity and stability are insufficient
Solution Approach 1:
The ohmic contact structure is divided into multiple functional layers: a first contact layer (Al-rich alloy) for primary electrical contact, a second contact layer (Cu-rich alloy) for enhanced conductivity, and an interlayer for oxidation prevention. Each layer performs a specific function, collectively achieving superior electrical properties while maintaining manageable structural complexity.
Solution Approach 2:
The patent employs composite material structures where Al-rich and Cu-rich alloy layers are combined with an interlayer material. This composite approach leverages the high electrical conductivity of Cu-rich alloys and the oxidation resistance of the interlayer, achieving reliability improvements that single-material contacts cannot provide.
2Reliability
If the ohmic contact structure is optimized for conductivity, then electrical conductivity improves, but heat generation increases
Solution Approach 1:
The patent converts the potential harm of heat generation into a benefit by using Cu-rich alloy layers that not only provide excellent electrical conductivity but also possess superior thermal conductivity. This allows efficient heat dissipation from the contact region, transforming what would be a harmful thermal accumulation into an advantageous heat management solution.
3Reliability
If aluminum layers are used for ohmic contact, then electrical conductivity is improved, but oxidation occurs reducing stability
Solution Approach 1:
An interlayer is introduced as an intermediary between the Al-rich contact layer and the external environment. This interlayer acts as a protective barrier that prevents oxygen from reaching and oxidizing the aluminum, thereby maintaining both the electrical conductivity provided by the Al-rich layer and the compositional stability required for long-term reliability.
4Stability of the object's composition
If multiple layers are added to prevent oxidation, then stability improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by providing oxidation protection specifically where it is most needed - at the aluminum contact interface - rather than uniformly throughout the entire device. The interlayer is strategically positioned only at the contact region, offering targeted protection while minimizing the overall structural complexity and material usage.
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 proposed solution significantly improves electrical conductivity and stability, reducing heat generation and enhancing light emission efficiency, while maintaining performance under high-temperature conditions.
Implementation Method 1
a first contact layer including an aluminum (Al) rich alloy, a second contact layer including a copper (Cu) rich alloy, and an interlayer disposed between the first contact layer and the second semiconductor layer
Implementation Method 2
an interlayer to prevent oxidation
Implementation Method 3
the use of a non-linear impedance region to reduce heat generation
Data Source
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Figure 3~5
Figure 6
AI summary
A light emitting device having an enhanced surface property and an electrical property is provided. The light emitting device includes a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer, a first electrode disposed on one side of the light emitting structure and electrically connected to the first semiconductor layer, a second electrode disposed on one side of the light emitting structure and electrically connected to the second semiconductor layer, and an ohmic contact including a first layer disposed between the second electrode and the second semiconductor layer and having aluminum (Al), a second layer including at least one MxAly alloy formed by a reaction with Al included in the first layer, and a third layer disposed on the second layer and having gold (Au) is provided.