Semiconductor Light Emitting Element With Periodic Recessed Structures
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Solution Overview
Problem
Conventional semiconductor light emitting elements face challenges in achieving high light extraction efficiency and uniform light output, particularly for short emission wavelengths, due to the difficulty in reproducibly and uniformly forming nanometer-scale recessed and projecting structures on the substrate surface, which affects the light extraction efficiency and stability of the output.
Innovation Solution
A semiconductor light emitting element with a periodic recessed and projecting structure on the substrate surface, where the period exceeds the emission wavelength, combined with a minute recessed and projecting structure, is fabricated using a method that includes dry etching with a fluorine-based gas, allowing for enhanced light extraction efficiency and uniformity, even for short emission wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a nanometer-scale recessed and projecting structure is formed on the substrate surface to improve light extraction efficiency, then the light extraction efficiency is improved, but the fabrication difficulty increases and manufacturing precision deteriorates
Solution Approach 1:
The invention changes the scale parameter of the recessed and projecting structure from nanometer-scale to micrometer-scale (period of 1-10 μm), making it compatible with conventional lithography fabrication processes while maintaining effective light extraction enhancement
Solution Approach 2:
The invention applies different structure characteristics at different locations: the periodic recessed and projecting structure is formed on the light extraction surface to suppress reflection, while minute recessed structures are formed in specific regions to further enhance light extraction, creating a composite structure with optimized local properties
2Loss of energy
If the period of the recessed and projecting structure is reduced to match shorter emission wavelengths to maintain light extraction efficiency, then the light extraction efficiency is maintained, but the fabrication difficulty increases
Solution Approach 1:
The invention changes the period parameter from nanometer-scale (required for short wavelengths) to micrometer-scale (1-10 μm), which can be fabricated using conventional lithography processes, thereby improving manufacturing ease while maintaining light extraction efficiency through the combined periodic and minute structures
3Loss of energy
If a periodic recessed and projecting structure is formed to suppress reflection, then the light extraction efficiency is improved, but the device complexity increases
Solution Approach 1:
The invention segments the light extraction enhancement function into two distinct components: a periodic recessed and projecting structure for suppressing reflection, and minute recessed structures for additional light extraction enhancement, allowing each component to be optimized independently and fabricated using separate process steps
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 combination of periodic and minute recessed and projecting structures effectively suppresses reflection and total reflection, resulting in high light extraction efficiency and uniform light output with improved reproducibility and reduced manufacturing costs, even for short emission wavelengths.
Implementation Method 1
when the light passes through a boundary between media having different refractive indexes, i.e., an interface between layers or a surface, a certain rate of reflection occurs inevitably
Implementation Method 2
when the light travels from a medium having a high refractive index to a medium having a low refractive index, total reflection of the light occurs and the light having an angle equal to or larger than a critical angle cannot be extracted to the outside
Implementation Method 3
a certain rate of reflection occurs inevitably
Implementation Method 4
a method that includes dry etching with a fluorine-based gas
Data Source
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AI summary
There are provided a semiconductor light emitting element that achieves high light extraction efficiency and uniform light output even if an emission wavelength is short, and a method for manufacturing the semiconductor light emitting element by which the semiconductor light emitting element can be manufactured with high reproducibility and high productivity. The semiconductor light emitting element is a semiconductor light emitting element comprising a semiconductor layer including a light emitting layer, wherein a surface of the semiconductor light emitting element includes a light extraction surface. At least one of the light extraction surface and an interface between two layers having different refractive indexes in the semiconductor light emitting element is provided with a periodic recessed and projecting structure having a period that exceeds 0.5 times as great as a wavelength of light emitted from the light emitting layer, and a minute recessed and projecting structure located on a surface of the periodic recessed and projecting structure and having an average diameter that is not more than 0.5 times as great as the wavelength of the light.