Light Emitting Device Angled Side Surfaces Extraction Efficiency
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Solution Overview
Problem
Semiconductor light emitting devices face low light extraction efficiency due to total reflection at the interface between high and low refractive index materials, leading to increased manufacturing costs when attempting to improve this efficiency through curved side surfaces.
Innovation Solution
A light emitting device with a semiconductor layer having a cladding layer and an active layer, where the cladding layer side surface is angled differently from the active layer side surface, allowing light reflected by the active layer to enter the extraction surface at an angle less than the critical angle, thereby improving extraction efficiency without the need for curved side surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the side surface is entirely processed to have a curved shape to improve light extraction efficiency, then the extraction efficiency is improved, but the manufacturing costs are increased
Solution Approach 1:
The patent applies local quality by differentiating the side surface angles between the cladding layer and active layer. The cladding layer side surface has a first angle while the active layer side surface has a second angle different from the first angle. This localized differentiation optimizes light extraction at the active layer interface without requiring the entire device structure to be curved, thereby reducing manufacturing complexity and costs while maintaining improved extraction efficiency.
Solution Approach 2:
The patent segments the side surface configuration into two distinct parts: the cladding layer side surface and the active layer side surface. Each segment is assigned a different angle relative to the extraction surface, allowing independent optimization of light extraction in different regions. This segmentation enables selective application of angle optimization where it is most needed (at the active layer) without the complexity of curving the entire structure.
2Ease of manufacture
If the extraction surface is made flat to reduce manufacturing complexity, then the manufacturing costs are decreased, but the light extraction efficiency is reduced due to total reflection
Solution Approach 1:
The patent changes the geometric parameters of the side surfaces by setting specific angles for the cladding layer side surface and active layer side surface relative to the extraction surface. By optimizing these angular parameters, the patent enables a flat extraction surface to achieve high light extraction efficiency. The angle configuration ensures that light reflected from the active layer side surface enters the extraction surface at angles that minimize total reflection, allowing the flat surface to outperform curved surfaces in terms of both manufacturing ease and 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 reduces manufacturing costs and enhances light extraction efficiency, achieving higher efficiency even with a flat extraction surface by optimizing the angle of the active layer side surface relative to the extraction surface.
Implementation Method 1
At an interface between a material having a high refractive index (semiconductor) and a material having a low refractive index (for example, air or resin), light incident at an angle greater than the critical angle is totally reflected.
Implementation Method 2
light incident at an angle greater than the critical angle is totally reflected
Data Source
AI summary
A light emitting device includes a semiconductor layer having a light extraction surface and side surfaces. The semiconductor layer includes a cladding layer and an active layer. The cladding layer has the extraction surface and a cladding layer side surface of the side surfaces, the cladding layer side surface being arranged at a first angle to the extraction surface. The active layer has an active layer side surface of the side surfaces, the active layer side surface being arranged at a second angle different from the first angle to the extraction surface.