Semiconductor Light Emitting Device Composite Metal Layer Adhesion
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Solution Overview
Problem
Semiconductor light emitting devices face challenges in achieving high luminous efficiency due to peeling issues caused by the use of metals with high optical reflectance, which compromise adhesion and lead to reduced light extraction efficiency.
Innovation Solution
Incorporating a metal layer with low reflectance and good adhesion, such as titanium or titanium-tungsten, and using an insulating unit with high adhesion to link the semiconductor light emitting unit to the metal layer, thereby suppressing peeling and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal layer with high optical reflectance is used to increase light extraction efficiency, then light extraction efficiency is improved, but adhesion strength deteriorates causing peeling
Solution Approach 1:
The patent uses a composite metal layer structure combining titanium (or titanium-tungsten alloy) with silver. The titanium layer provides strong adhesion to the semiconductor layer, while the silver layer provides high optical reflectance for light extraction. This composite structure resolves the contradiction between adhesion strength and light extraction efficiency by assigning different functions to different materials in the composite layer.
2Loss of energy
If a metal layer with high optical reflectance is used to enhance luminous efficiency, then luminous efficiency is improved, but peeling occurs reducing device reliability
Solution Approach 1:
The composite metal layer structure with titanium and silver addresses the contradiction between luminous efficiency and peeling resistance. The titanium component ensures strong bonding preventing peeling, while the silver component maximizes optical reflectance to enhance luminous efficiency, thus resolving the contradiction.
Solution Approach 2:
The patent applies different material properties to different parts of the metal layer: titanium provides local adhesion quality at the interface with the semiconductor, while silver provides local optical reflectance quality for light extraction. This local differentiation of material qualities resolves the contradiction between peeling resistance and luminous efficiency.
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 increases luminous efficiency and prevents peeling, resulting in a practical semiconductor light emitting device with improved light extraction and reliability.
Implementation Method 1
Incorporating a metal layer with low reflectance and good adhesion, such as titanium or titanium-tungsten
Data Source
Figure 1A~1B
Figure 2~4B
Figure 5~6B
AI summary
According to one embodiment, a semiconductor light emitting device (110, 110a, 110b, 111, 112) includes a first metal layer (51), a second metal layer (52), a third metal layer (53), a semiconductor light emitting unit (15) and an insulating unit (80). The semiconductor light emitting unit (15) is separated from the first metal layer (51) in a first direction. The second metal layer (52) is provided between the first metal layer (51) and the semiconductor light emitting unit (15) to be electrically connected to the first metal layer (51), and is light-reflective. The second metal layer (52) includes a contact metal portion (52c), and a peripheral metal portion (52p). The third metal layer (53) is light-reflective. The third metal layer (53) includes an inner portion (53i), a middle portion (53m), and an outer portion (53o). The insulating unit (80) includes a first insulating portion (81), a second insulating portion (82), and a third insulating portion (83). According to the embodiment, a practical semiconductor light emitting device (110, 110a, 110b, 111, 112) having high luminous efficiency can be provided.