Semiconductor Light Emitting Device Reflective Layer Optimization
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in optimizing reflection characteristics and external light-emitting efficiency, particularly in adjusting the thickness and number of layers in reflective structures to match the wavelength of emitted light.
Innovation Solution
A semiconductor light emitting device is designed with a reflective layer having a Distributed Bragg Reflector (DBR) structure, comprising alternately stacked mediums with different refractive indices, allowing for adjustable thickness and number of pairs based on the wavelength of emitted light, and an ohmic layer and conductive support member for improved reflection and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple reflective layer is used, then the device structure is simple, but the reflection characteristics and external light-emitting efficiency are insufficient
Solution Approach 1:
The reflective layer is constructed as a composite structure with multiple alternating layers of different materials (e.g., GaN and AlN) having different refractive indices. This composite configuration enables enhanced reflection characteristics through constructive interference of light waves, while maintaining a manageable manufacturing process for III-V nitride semiconductor devices.
2Reliability
If the thickness and number of layers in the reflective layer are increased to improve reflection characteristics, then external light-emitting efficiency improves, but device complexity increases
Solution Approach 1:
The patent optimizes the thickness and number of layers in the reflective layer by adjusting key parameters such as layer thickness (e.g., quarter-wavelength thickness), refractive index contrast, and the number of alternating layers. These parameter changes enable high reflection characteristics without excessively increasing device complexity, as the optimization can be achieved through systematic design rather than trial and error.
3Manufacturing precision
If the reflective layer is optimized for a specific wavelength, then reflection characteristics at that wavelength are high, but adaptability across a wide wavelength range is reduced
Solution Approach 1:
The reflective layer is designed with multiple alternating layers of different materials that can reflect light across a broad wavelength range (e.g., 300 nm to 700 nm). By selecting materials with appropriate refractive indices and arranging them in a multi-layer configuration, the structure achieves universal reflectivity for different wavelengths, enabling the LED to maintain high external quantum efficiency across various color outputs.
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 reflection characteristics and external light-emitting efficiency by optimizing the thickness and number of pairs in the reflective layer, achieving high reflectance and improved performance across a wide wavelength range (300 nm to 700 nm).
Implementation Method 1
a reflective layer comprising mediums, which are different from each other and alternately stacked under the light emitting structure
Implementation Method 2
The embodiment can improve reflection characteristics by adopting a reflective layer having a DBR (Distributed Bragg Reflector) structure
Data Source
AI summary
Disclosed is a semiconductor light emitting device. The semiconductor light emitting device comprises a light emitting structure comprising a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; a reflective layer under the light emitting structure; a first electrode layer on the first conductive semiconductor layer; a metal layer under the reflective layer; and a conductive support member under the metal layer. The reflective layer has a thickness of 650 nm to 1550 nm. A top surface of the first conductive semiconductor layer includes a flat first region adjacent to an edge and a rough second region adjacent to the first region. An edge region of a top portion of the conductive support member has a protrusion, and the edge region of the top portion of the conductive support member is not overlapped with the light emitting structure in a vertical direction.