Light-Emitting Element With Inclined Reflective Layer
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) suffer from low light output efficiency due to total internal reflection, with most emitted light being reflected back into the semiconductor layer, resulting in power output efficiencies ranging from 2.21% to 4.18% without additional processing.
Innovation Solution
A light-emitting element with a substrate structure comprising a first substrate and a transparent second substrate, where a reflective layer is formed between them at an inclined angle to increase the chances of light reflection and output, and a manufacturing method involving the formation of recess structures and conformal reflective layers to enhance light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional LED structure is used with a semiconductor layer directly exposed to air, then the device is simple in structure, but most emitted light is reflected back inside due to refractive index mismatch, resulting in low power output efficiency (2.21%-4.18%)
Solution Approach 1:
The patent introduces a substrate structure with a reflective layer as an intermediary component between the semiconductor layer and the external environment. This reflective layer acts as a mediator to redirect light that would otherwise be lost through total internal reflection, thereby improving light output efficiency without significantly complicating the manufacturing process
Solution Approach 2:
The patent extracts light from the conventional top surface emission by introducing side surface emission through the substrate structure. This dimensional change in light extraction path allows light to escape through previously unused directions, improving overall light output efficiency
2Loss of energy
If a roughening process is applied to the semiconductor layer surface to scatter light, then light output probability is increased, but the manufacturing process becomes more complex and costly
Solution Approach 1:
Instead of modifying the semiconductor layer itself through roughening processes, the patent introduces a separate substrate structure with a reflective layer as an intermediary. This approach achieves light scattering and redirection without altering the semiconductor layer, thereby avoiding the complexity and cost of additional manufacturing steps
Solution Approach 2:
The patent applies the reflective layer and substrate structure only in specific locations where light extraction is needed, rather than modifying the entire semiconductor device. This localized approach improves light output efficiency while minimizing additional manufacturing complexity
3Loss of energy
If the original substrate is removed and the semiconductor layer is bonded to a large substrate with a reflective layer, then light output probability is increased through additional reflection opportunities, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates the reflective layer and substrate structure during the initial fabrication process, performing the light extraction enhancement action in advance. This preliminary integration avoids the need for complex post-fabrication substrate removal and re-bonding operations, thereby improving light output efficiency while maintaining manufacturing simplicity
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 described configuration significantly enhances light output efficiency by allowing more light to be reflected and emitted from the side surfaces of the substrate, potentially increasing power output efficiency beyond conventional limits.
Implementation Method 1
a reflective layer formed between the first substrate and the second substrate and having an inclined angle not perpendicular to the first surface to reflect the light emitted from the light-emitting stack
Implementation Method 2
a second substrate disposed under the light-emitting stack and being a transparent substrate
Data Source
AI summary
A light-emitting element includes a light-emitting stack for emitting light and a substrate structure including: a first substrate disposed under the light-emitting stack and having a first surface facing the light-emitting stack; and a second substrate disposed under the light-emitting stack and having a second surface facing the light-emitting stack; and a reflective layer formed between the first substrate and the second substrate and having an inclined angle not perpendicular to the first surface.