Nanowire Light-Emitting Structure for Upper-Surface Light Extraction
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Solution Overview
Problem
Semiconductor light-emitting elements with columnar nanowires face limited light extraction efficiency from the upper surface due to light scattering and absorption by surrounding nanowires, necessitating an optical path conversion technique to redirect light emitted in the side surface direction to the upper surface, which complicates the package and manufacturing process.
Innovation Solution
A semiconductor light-emitting element with columnar semiconductor layers and an embedded layer featuring gaps between the layers, where the embedded layer is designed to reflect or scatter light traveling laterally, increasing the amount of light emitted from the upper surface, using a GaN substrate and an ITO film, and incorporating a p-type semiconductor layer and transparent electrode for enhanced light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an optical path conversion technique (reflecting mirror) is provided outside the semiconductor light-emitting element to convert light emitted in the side surface direction into the upper surface direction, then the light extraction efficiency from the upper surface is improved, but the package structure becomes complicated
Solution Approach 1:
The patent combines the optical path conversion function directly into the semiconductor light-emitting element structure by integrating a reflecting mirror layer within the element itself, rather than placing it externally in the package. This merging of functions improves upper surface light extraction while avoiding package complexity.
Solution Approach 2:
The reflecting mirror layer is nested within the semiconductor light-emitting element structure, specifically positioned between the active layer and the lower cladding layer. This nesting approach allows the optical conversion function to be embedded inside the element, eliminating the need for external mirrors in the package.
2Illumination intensity
If an optical path conversion technique including a mirror surface is formed inside the semiconductor light-emitting element, then the light extraction efficiency from the upper surface is improved, but the manufacturing process becomes complicated
Solution Approach 1:
The reflecting mirror layer is formed using the same epitaxial growth process that creates the semiconductor layers themselves. The mirror layer forms in situ during the growth process, eliminating the need for separate mirror formation steps and simplifying manufacturing.
Solution Approach 2:
The reflecting mirror layer is created by changing the doping parameters during epitaxial growth - specifically by forming an n-type doped region with higher doping concentration than the surrounding layers. This parameter-based approach to creating the mirror function avoids complex post-growth processing.
3Power
If columnar nanowires are used to prevent power efficiency decrease in high current region, then the light emission capability is improved, but the light extraction efficiency from the upper surface is limited due to light scattering and absorption by surrounding nanowires
Solution Approach 1:
The reflecting mirror layer acts as an intermediary that redirects light which would otherwise be lost through scattering and absorption by surrounding nanowires. The mirror reflects this light upward through the active layer, converting side-emitted light into upper-surface-emitted light and improving overall 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 allows for a significant increase in light emission from the upper surface with a simple and efficient manufacturing process, improving light extraction efficiency without complicating the package or manufacturing process.
Implementation Method 1
light is affected by light scattering, light absorption, and the like due to the surrounding nanowires
Implementation Method 2
the embedded layer is designed to reflect or scatter light traveling laterally
Implementation Method 3
The semiconductor light-emitting element emits light by recombination of positive holes and electrons in an active layer
Data Source
AI summary
A semiconductor light-emitting element includes: a growth substrate; a plurality of columnar semiconductor layers on the growth substrate; and an embedded layer with which the plurality of columnar semiconductor layers are covered. Each of the plurality of columnar semiconductor layers includes: an n-type nanowire layer at a center of each of the columnar semiconductor layers; and an active layer on an outer periphery side of the n-type nanowire layer. The embedded layer defines a gap above the growth substrate between adjacent columnar semiconductor layers of the plurality of columnar semiconductor layers.