Nitride Semiconductor Light Emitting Device with Reflective Layer
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Solution Overview
Problem
Current nitride semiconductor light emitting devices face challenges in achieving high light extraction efficiency, which is essential for improving internal quantum efficiency and overall emission efficiency.
Innovation Solution
A light emitting device structure is optimized by incorporating a reflective layer, a transparent oxide layer, and a semiconductor layer with a photonic crystal structure, where the distance between the reflective layer and the light emitting layer is adjusted to achieve constructive interference, and the photonic crystal structure's etching depth is optimized to maximize light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between the reflective layer and the light emitting layer is increased to improve light extraction efficiency, then light extraction efficiency is improved, but device structure complexity increases
Solution Approach 1:
A transparent oxide layer is introduced as an intermediary layer between the reflective layer and the light emitting layer. This intermediary layer enables precise control of the optical path length and interference conditions, achieving optimized light extraction efficiency while maintaining a manageable structural complexity through its transparent and conductive properties
Solution Approach 2:
The thickness of the transparent oxide layer is precisely controlled to satisfy specific optical interference conditions (optical path length of λ/4, 3λ/4, 5λ/4, etc.). By changing the optical parameters (refractive index and thickness) of the intermediary layer, the system achieves optimal light extraction efficiency without requiring excessive structural complexity
2Productivity
If a photonic crystal structure is added to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
A photonic crystal structure with periodic porous patterns is formed in the transparent oxide layer. These periodic voids or lower-refractive-index regions create optical interference effects that enhance light extraction efficiency. The porous structure is integrated into the existing transparent oxide layer deposition process, avoiding completely separate manufacturing steps
Solution Approach 2:
The photonic crystal structure employs periodic curved or rounded patterns (such as cylindrical holes or dome-shaped regions) within the transparent oxide layer. These curved structures effectively manipulate light propagation and extraction while being compatible with standard semiconductor fabrication processes like spin coating, photolithography, and etching
3Productivity
If the transparent oxide layer thickness is increased to adjust the distance for constructive interference, then light extraction efficiency is improved, but internal quantum efficiency may deteriorate
Solution Approach 1:
The thickness of the transparent oxide layer is precisely controlled to satisfy specific optical interference conditions (optical path length of λ/4, 3λ/4, 5λ/4, etc.). By changing the optical parameters (refractive index and thickness) of the intermediary layer, the system achieves optimal light extraction efficiency without excessive thickness increase that would harm internal quantum efficiency
Solution Approach 2:
The transparent oxide layer is designed as a composite structure combining transparent conductive oxide (TCO) materials with specific refractive indices. This composite approach allows simultaneous optimization of electrical conductivity (for carrier injection), optical properties (for interference control), and thickness (for light extraction), preventing deterioration of internal quantum efficiency while achieving high 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 enhances light extraction efficiency by adjusting the distance between the reflective and light emitting layers and optimizing the photonic crystal structure, resulting in improved output orientation and extraction efficiency, potentially increasing extraction efficiency by up to two times.
Implementation Method 1
a distance 'd' between the reflective layer and a center of the light emitting layer corresponds to a constructive interference condition
Implementation Method 2
a light emitting device structure is optimized by incorporating a reflective layer, a transparent oxide layer, and a semiconductor layer with a photonic crystal structure
Data Source
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AI summary
A light emitting device is provided. The light emitting device comprises: a reflective layer; and a semiconductor layer including a light emitting layer on the reflective layer. A distance between the reflective layer and a center of the light emitting layer corresponds to a constructive interference condition.