GaN Columnar Light Emitter With AlGaN Layer for Light Confinement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor laser designs with continuous p-type GaN layers over nano-columns suffer from high in-plane refractive index, leading to light leakage and optical loss due to the absence of air gaps, which hinders light confinement and efficiency.
Innovation Solution
A light emitting apparatus with a laminated structure featuring columnar sections of n-type and p-type GaN layers separated by a low refractive index AlGaN layer, including a p-type AlGaN layer with distinct sections between adjacent columnar sections and the electrode, to reduce the average refractive index and enhance light confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous p-type GaN layer is formed over multiple columnar sections, then the layer provides good electrical continuity, but the high average refractive index causes light leakage and optical loss
Solution Approach 1:
The p-type GaN layer is segmented into multiple discrete sections rather than forming a continuous layer. Each p-type GaN section is positioned over individual columnar sections, with low refractive index regions (air gaps or AlGaN layers) separating them. This segmentation maintains electrical continuity through the columnar structure while reducing the average in-plane refractive index to confine light effectively.
Solution Approach 2:
Different regions of the p-type GaN layer have different properties: regions directly over columnar sections have high refractive index for good electrical contact, while regions between columnar sections have low refractive index for light confinement. This local variation in refractive index allows simultaneous achievement of electrical continuity and optical confinement.
2Stability of the object's composition
If the diameter of nano-columns increases during growth, then the structure becomes more stable, but air gaps disappear and light confinement is reduced
Solution Approach 1:
Even when columnar sections have increased diameter for structural stability, the p-type GaN layer is segmented into discrete sections with low refractive index regions between them. This prevents the formation of a continuous high refractive index layer that would cause light leakage, while still allowing the columnar sections themselves to have stable, larger dimensions.
Solution Approach 2:
Low refractive index regions (air gaps or AlGaN layers) act as intermediary elements between the columnar sections. These intermediaries maintain the optical confinement function even when the columnar sections have increased diameter, preventing direct optical coupling between adjacent columns that would lead to light leakage.
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 emitting layers, reducing leakage and absorption, increasing current injection efficiency, and maintaining high electrical conductivity, thereby improving the overall light output and efficiency of the semiconductor laser.
Implementation Method 1
the layer has a high average refractive index in the in-plane direction. It is therefore difficult to confine light in the light emitting layer
Implementation Method 2
a light emitting layer provided between the first GaN layer and the second GaN layer
Data Source
AI summary
A light emitting apparatus includes a substrate, a laminated structure provided at the substrate and including a plurality of columnar sections, and an electrode provided on the side opposite the substrate with respect to the laminated structure and injecting current into the laminated structure. The columnar sections each include an n-type first GaN layer, a p-type second GaN layer, and a light emitting layer provided between the first GaN layer and the second GaN layer. The first GaN layers are provided between the light emitting layers and the substrate. The laminated structure includes a p-type first AlGaN layer. The first AlGaN layer includes a first section provided between the second GaN layers of the columnar sections adjacent to each other and a second section provided between the first section and the electrode and between the columnar sections and the electrode.