Columnar Light-Emitting Device Taper Angles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor light-emitting devices face challenges in increasing the optical confinement factor due to limited material choices, leading to light leakage and absorption by electrodes, which reduces efficiency.
Innovation Solution
A light-emitting device with a laminated structure featuring columnar parts, including an n-type first semiconductor layer, a light-emitting layer, and a p-type second semiconductor layer, where the taper angles of the facet surfaces are optimized to increase the refractive index difference, and indium gallium nitride compositions are used to reduce lattice constant differences and strain, thereby minimizing light absorption by the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If material choices are limited due to lattice matching conditions, then the compatibility between active layer and substrate is maintained, but the difference in refractive index between active layer and cladding layer cannot be increased
Solution Approach 1:
The invention changes the refractive index parameter by introducing a low-refractive-index layer with specific material composition (organic compound layer or oxide semiconductor layer) between the semiconductor layers and electrode. This parameter change increases the refractive index difference without altering the lattice-matched semiconductor material system, thereby reducing light absorption by the electrode while maintaining lattice compatibility.
2Loss of energy
If the optical confinement factor is increased by increasing refractive index difference, then light confinement in the active layer is improved, but material choices are greatly limited due to lattice matching requirements
Solution Approach 1:
The invention segments the device structure by introducing a separate low-refractive-index layer distinct from the lattice-matched semiconductor layers. This segmentation allows the optical confinement function to be achieved by the inserted layer with different material properties, while the semiconductor layers maintain their lattice-matched composition for efficient light emission, thus decoupling the two requirements.
Solution Approach 2:
The low-refractive-index layer acts as an intermediary between the semiconductor layers and the electrode. This intermediary layer provides the necessary refractive index difference for optical confinement while being compatible with the existing lattice-matched semiconductor structure, thereby enabling improved light confinement without restricting material choices for the active layers.
3Illumination intensity
If light is generated in the active layer, then light emission function is achieved, but light leaks out toward the electrode and is absorbed by the electrode
Solution Approach 1:
The invention converts the harmful effect of light propagation toward the electrode into a beneficial outcome by strategically placing a low-refractive-index layer that redirects light confinement. The layer that would normally cause absorption loss is transformed into a light-managing element that enhances confinement by creating a refractive index contrast that bends light back into the active layer, turning the potential harm into improved light emission 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
The optimized structure enhances light emission efficiency by reducing light leakage and absorption, improving the optical confinement factor and crystal quality, leading to higher light emission efficiency and reduced strain in the light-emitting layer.
Implementation Method 1
a light-emitting device includes: a substrate; and a laminated structure provided at the substrate and having a plurality of columnar parts. The columnar part has: an n-type first semiconductor layer; a p-type second semiconductor layer; a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer
Implementation Method 2
An end part on aside opposite to aside of the substrate, of the light-emitting layer, has a first facet surface. An end part on aside opposite to aside of the substrate, of the second semiconductor layer, has a second facet surface. A relation of θ2≤θ1 is satisfied, where θ1 is a taper angle of the first facet surface, and θ2 is a taper angle of the second facet surface.
Data Source
AI summary
A light-emitting device includes: a substrate; and a laminated structure provided at the substrate and having a plurality of columnar parts. The columnar part has: an n-type first semiconductor layer; a p-type second semiconductor layer; a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer; and an electrode provided on a side opposite to a side of the substrate, of the laminated structure. The first semiconductor layer is provided between the light-emitting layer and the substrate. An end part on a side opposite to a side of the substrate, of the light-emitting layer, has a first facet surface. An end part on a side opposite to a side of the substrate, of the second semiconductor layer, has a second facet surface. A relation of θ2≤θ1 is satisfied, where θ1 is a taper angle of the first facet surface, and θ2 is a taper angle of the second facet surface. θ1 is 70° or smaller, and θ2 is 30° or greater.