Semiconductor Light Emitting Device Refractive Index Optimization
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Solution Overview
Problem
Existing semiconductor light emitting devices have limitations in light extraction efficiency due to reflection issues at interfaces within their structure.
Innovation Solution
A semiconductor light emitting device configuration is implemented with specific refractive index relationships between layers (n1>n2<n3) and optimized thicknesses (odd multiple of λ/4) to reduce reflection and enhance light extraction, using materials like p-type GaP, SiO2, and ITO, and incorporating a contact hole structure for improved metal connection and reduced contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional semiconductor light emitting device structure is used, then the device can be manufactured with standard processes, but light extraction efficiency is limited due to reflection at interfaces
Solution Approach 1:
The patent changes the refractive index parameter by introducing a light-transmitting conductive layer with refractive index n3 between the insulation layer (n2) and the light emitting layer (n1), where n2 < n3 < n1. This gradient refractive index structure reduces reflection at interfaces and improves light extraction efficiency without requiring complex manufacturing processes
Solution Approach 2:
The light-transmitting conductive layer acts as an intermediary layer between the insulation layer and the light emitting layer. This intermediate layer with refractive index n3 serves as a transition medium that reduces the abrupt refractive index mismatch, thereby reducing reflection and improving light extraction efficiency
2Loss of energy
If the refractive index relationship n1>n2<n3 is implemented, then light extraction efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The light-transmitting conductive layer serves multiple functions: it provides electrical conduction, optical transmission with appropriate refractive index for light extraction enhancement, and structural integration with existing device layers. This multi-functionality improves light extraction efficiency without proportionally increasing device complexity
Solution Approach 2:
The patent uses a composite structure combining the insulation layer, light-transmitting conductive layer, and light emitting layer with specific refractive index relationships. This composite material approach creates a gradient refractive index structure that enhances light extraction while maintaining manageable structural complexity
3Loss of energy
If the total thickness T is optimized to an odd multiple of λ/4, then reflectance at the interface is reduced and light extraction is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary optical design by calculating and setting the total thickness T of the insulation layer and light-transmitting conductive layer to an odd multiple of λ/4 before manufacturing. This preliminary optimization of the optical path length ensures that reflected waves from different interfaces interfere destructively, reducing overall reflectance and enhancing light extraction 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 configuration significantly improves light extraction efficiency by minimizing reflection at interfaces and increasing the amount of light reflected by the metal layer, while maintaining a simple structure and reducing disconnection failures.
Implementation Method 1
a refractive index n1 of the first conductive type layer, a refractive index n2 of the insulation layer, and a refractive index n3 of the light-transmitting conductive layer satisfy the relation: n1>n2>n3
Implementation Method 2
the reflection of light at the insulation layer/light-transmitting layer interface (first interface) can be suppressed
Implementation Method 3
The light incident on the light-transmitting conductive layer without being reflected by the first conductive type layer/insulation layer interface (second interface) can reach the metal layer and can be efficiently reflected by the metal layer
Implementation Method 4
a total thickness T comprising a sum of optical film thicknesses of the light-transmitting conductive layer and the insulation layer can be an odd multiple of λ/4 (where λ is an emission wavelength)
Implementation Method 5
The semiconductor layer comprises a light emitting layer
Data Source
AI summary
The present invention provides a semiconductor light emitting device with a simple structure and capable of improving light extraction efficiency. The semiconductor light emitting device 1 includes a substrate 2, a metal layer 3 on the substrate 2, a light-transmitting conductive layer 4 on the metal layer 3, an insulation layer 30 on the light-transmitting conductive layer 4, and a III-V semiconductor structure 5 on the insulation layer 30. The III-V semiconductor structure 5 includes a light emitting layer 8, a p-type semiconductor layer 9, and an n-type semiconductor layer 10. A refractive index n1 of a p-type GaP contact layer 11 of the p-type semiconductor layer 9, a refractive index n2 of the insulation layer 30, and a refractive index n3 of the light-transmitting conductive layer 4 satisfy the relation: n1>n2<n3.