Semiconductor Light-Emitting Device with Refractive Index Contrast
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Solution Overview
Problem
Semiconductor light-emitting devices face challenges in achieving high light extraction efficiency, particularly in high-current and high-power applications, where existing structures fail to effectively convert and transmit light due to total internal reflection and re-incidence issues.
Innovation Solution
Incorporating a light control layer with alternating layers of insulating materials of different refractive indices between the light-emitting stack and the wavelength conversion layer, along with a micro lens portion to enhance light transmittance and reflectance, thereby improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light-emitting stack structure is used, then the device structure is simple, but light extraction efficiency is low due to total internal reflection and re-incidence issues
Solution Approach 1:
The light control layer is divided into multiple alternating insulating layers with different refractive indices (first insulating layer with lower refractive index, second insulating layer with higher refractive index). This segmentation creates multiple interfaces that manipulate light propagation, reducing total internal reflection and improving light extraction efficiency without overly complicating the manufacturing process.
Solution Approach 2:
The light control layer acts as an intermediary between the light-emitting stack and the wavelength conversion layer. By introducing this intermediate structure with specific refractive index properties, the patent mediates the optical interaction between the semiconductor layers and the phosphor, enhancing light extraction while maintaining a manageable device architecture.
2Productivity
If alternating insulating layers with different refractive indices are introduced, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent utilizes parameter changes in refractive index by alternating between insulating layers with different refractive indices (first layer with lower index, second layer with higher index). This parameter variation creates optical contrast that enhances light extraction efficiency. The thickness parameters are also optimized (first layer: 1-96 nm, second layer: 64-180 nm) to achieve the desired optical performance while controlling structural complexity.
Solution Approach 2:
The light control layer employs composite material structure by combining different insulating materials with distinct refractive indices. This composite approach allows precise control over optical properties, achieving high light extraction efficiency. The specific material combinations (e.g., SiO2 with TiO2, MgF2 with Si3N4) provide the necessary refractive index contrast while maintaining compatibility with standard semiconductor manufacturing processes.
3Productivity
If the first insulating layer has lower refractive index and the second has higher refractive index by 0.5 or more, then transmittance of emitted light is increased, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the insulating layers: the refractive index difference between the first and second insulating layers must be 0.5 or more, with the first layer having lower index and the second layer having higher index. The thickness parameters are also defined (first layer: 1-96 nm, second layer: 64-180 nm). These parameter specifications enable optimized light transmittance while providing clear manufacturing targets that balance precision requirements with achievable fabrication capabilities.
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 structure significantly increases transmittance of emitted light and reflectance of re-incident light, leading to enhanced light extraction efficiency and improved performance in high-current and high-power applications.
Implementation Method 1
a first insulating layer having a lower refractive index than a refractive index of the light-emitting stack, and a second insulating layer having a higher refractive index than a refractive index of the first insulating layer by 0.5 or more
Implementation Method 2
total internal reflection and re-incidence issues
Implementation Method 3
configured to convert at least some of light having a first wavelength, emitted from the active layer, into light having a second wavelength
Data Source
AI summary
A semiconductor light-emitting device includes a light-emitting stack including a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an active layer disposed between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer, a wavelength conversion layer disposed on the light-emitting stack and configured to convert at least some of light having a first wavelength, emitted from the active layer, into light having a second wavelength, and a light control layer disposed between the light-emitting stack and the wavelength conversion layer, and including a first insulating layer and a second insulating layer, the first insulating layer having a refractive index lower than a refractive index of the light-emitting stack, and the second insulating layer having a refractive index higher than a refractive index of the first insulating layer by 0.5 or more.