Nitride Surface Emitting Laser Dislocation Isolation
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Solution Overview
Problem
Surface emitting lasers with nitride semiconductors face challenges in improving device characteristics such as reliability due to high dislocation densities in the semiconductor layers, which affect light emission.
Innovation Solution
The surface emitting laser design includes a semiconductor layer with a high dislocation portion outside the light emitting region, using a lateral growth technique to form the semiconductor layers, and a method of manufacturing that positions the light emitting region away from the high dislocation areas, thereby minimizing their influence on light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a nitride semiconductor is used to cover a wide wavelength range, then the device can emit light at shorter wavelengths, but high dislocation density in the semiconductor layer degrades reliability
Solution Approach 1:
The patent segments the semiconductor layer into distinct regions: a first semiconductor layer containing high dislocation portions (formed in seed regions) and a second semiconductor layer forming the light emitting region. This segmentation isolates dislocations to specific areas, preventing them from affecting the light emitting region and thus maintaining device reliability while using nitride semiconductors for wide wavelength coverage
Solution Approach 2:
The invention extracts and removes the growth substrate after forming the semiconductor layers. This extraction eliminates the source of dislocations (the substrate) from the final device structure, allowing the light emitting region to be free from substrate-induced dislocations while maintaining the benefits of nitride semiconductor material
2Ease of manufacture
If the light emitting region is formed in the seed region with high dislocation density, then the manufacturing process is simplified, but light emission is significantly affected by dislocations
Solution Approach 1:
The patent applies local quality by creating different regions with different properties: the first semiconductor layer in seed regions has high dislocation density and is excluded from light emission, while the second semiconductor layer has low dislocation density and is specifically designed for light emission. This allows the light emitting region to have optimal quality while other regions can accommodate manufacturing requirements
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 approach enhances the reliability and device characteristics of the surface emitting laser by isolating the light emitting region from high dislocation portions, reducing diffraction losses and maintaining efficient light reflection, even with high dislocation densities in the semiconductor layers.
Implementation Method 1
a first light reflecting layer and a second light reflecting layer that are opposed to each other with the semiconductor layer being disposed therebetween
Data Source
AI summary
A surface emitting laser includes: a semiconductor layer containing a nitride semiconductor, and including a first semiconductor layer, an active layer, and a second semiconductor layer that are stacked in this order, in which the semiconductor layer includes a light emitting region; and a first light reflecting layer and a second light reflecting layer that are opposed to each other with the semiconductor layer being disposed therebetween. The first semiconductor layer has a high dislocation portion disposed outside the light emitting region. The high dislocation portion has an average dislocation density higher than an average dislocation density of the light emitting region.