Semiconductor Light Emitting Device With Frosted Layer
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Solution Overview
Problem
Conventional semiconductor light emitting devices face issues with low brightness due to thermal diffusion of Sn from Au-Sn alloy layers, optical absorption at metal-semiconductor interfaces, and inefficient reflection by DBR layers, which reduce light emission efficiency.
Innovation Solution
The use of a metallic reflecting layer formed using a metal layer, such as Au, between the semiconductor substrate and the light emitting diode structure, with a transparent insulating film intervening between the metal and semiconductor to prevent optical absorption and enhance reflection, allowing for high luminance and total angle reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic reflecting layer is formed using Au-Sn alloy layer for wafer bonding, then bonding strength is improved, but Sn diffusion occurs reducing reliability
Solution Approach 1:
A barrier metal layer is introduced as an intermediary between the Au-Sn alloy bonding layer and the semiconductor layers. This barrier layer prevents Sn diffusion into the semiconductor while maintaining the bonding strength provided by the Au-Sn alloy layer, thus resolving the contradiction between bonding strength and reliability.
2Illumination intensity
If a metallic reflecting layer is formed directly on semiconductor layer, then optical reflection is improved, but optical absorption at metal-semiconductor interface reduces brightness
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metallic reflecting layer and the semiconductor layer. This dielectric layer eliminates direct metal-semiconductor contact, preventing optical absorption at the interface while preserving the high reflection properties of the metal layer, thus resolving the contradiction between optical reflection and energy loss.
3Ease of manufacture
If DBR layer is used for optical reflection, then manufacturing is simplified, but reflection efficiency is insufficient reducing brightness
Solution Approach 1:
The patent changes the material parameter of the reflecting layer from dielectric (DBR) to metal, which has inherently higher reflection efficiency. This parameter change maintains manufacturing simplicity through wafer bonding while dramatically improving reflection efficiency and brightness, resolving the contradiction between ease of manufacture and reflection 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
This approach eliminates the need for barrier metals, improves optical reflection, and achieves high brightness by preventing Sn diffusion and optical absorption, enabling efficient light emission across all angles.
Implementation Method 1
optical absorption at metal-semiconductor interfaces
Implementation Method 2
allowing for high luminance and total angle reflection
Implementation Method 3
thermal diffusion of Sn from Au-Sn alloy layers
Data Source
AI summary
A semiconductor light emitting device includes a conductive substrate and a first metal layer disposed on the substrate. The first metal layer is formed so as to be electrically connected with the substrate, and the first metal layer includes an Au based material. A joining layer is formed on the first metal layer. The joining layer includes a second metal layer including Au and a third metal layer including Au. A metallic contact layer and an insulating layer are formed on the joining layer. A semiconductor layer is formed on the metallic contact layer and the insulating layer and includes a red-based light emitting layer. An electrode is formed on the semiconductor layer and is made of metal. The insulating layer includes a patterned aperture, and at least a part of the metallic contact layer is formed in the aperture.