Columnar Light-Emitting Device for Reduced Leakage
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Solution Overview
Problem
Existing semiconductor lasers with nanostructures face challenges in achieving a significant difference in refractive index between layers, leading to light leakage issues due to limited material choices for the columnar portions, which affects the efficiency of light emission.
Innovation Solution
A light-emitting device is designed with a stack of columnar portions, where each portion includes specific semiconductor layers and a light-emitting layer, and a light propagation layer is used to manage refractive indices and layer diameters, allowing for effective light confinement and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional semiconductor laser structures with limited material choices are used, then manufacturing is simpler, but light confinement is insufficient due to inadequate refractive index difference between layers
Solution Approach 1:
The patent applies local quality by creating columnar portions with different diameters at different heights (first columnar portion with larger diameter at lower height, second columnar portion with smaller diameter at upper height). This local structural variation enables different refractive index characteristics in different regions, improving light confinement at the light-emitting layer without requiring complex overall device redesign
Solution Approach 2:
The patent uses composite material structures by combining multiple semiconductor layers (n-type layer, active layer, p-type layer) with different refractive indices within the columnar portions. The light propagation layer filled with resin material also creates a composite structure that enhances the refractive index difference, effectively confining light without excessive device complexity
2Loss of energy
If the second columnar portion has the same diameter as the first columnar portion, then manufacturing is easier, but light leaks to the side opposite to the substrate due to insufficient refractive index difference
Solution Approach 1:
The patent segments the columnar portion into two distinct parts: a first columnar portion at the lower height and a second columnar portion at the upper height, each with different diameters. This segmentation allows independent optimization of each section's light confinement properties, with the narrower second columnar portion providing better lateral light confinement at the light-emitting layer
Solution Approach 2:
The patent changes the diameter parameter of the columnar portion at different heights. The second columnar portion has a smaller diameter than the first columnar portion, creating a tapered structure that enhances the effective refractive index difference at the light-emitting layer, thereby reducing light leakage without requiring extremely tight manufacturing tolerances
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 solution effectively confines light within the light-emitting layer, reducing leakage and enhancing the photonic crystal effect, thereby improving the efficiency and directionality of light emission.
Implementation Method 1
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light
Implementation Method 2
semiconductor lasers using nanostructures (nanocolumns) are expected to be capable of realizing high-power light emission with narrow radiation angle by a photonic crystal effect created by the nanostructures
Data Source
AI summary
A light-emitting device includes a substrate and a stack provided on the substrate. The stack includes a plurality of columnar portions each of which includes a first columnar portion and a second columnar portion which has a diameter smaller than a diameter of the first columnar portions. Each first columnar portion is provided between the substrate and the second columnar portions, and includes: a first semiconductor layer; a second semiconductor layer having a conductivity type different from a conductivity type of the first semiconductor layer; and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of generating light. The first semiconductor layer is provided between the substrate and the light-emitting layer. Each second columnar portion includes a third semiconductor layer having a conductivity type different from a conductivity type of the first semiconductor layer.