Back-Emitting Laser Structure With Low-Defect Bonded Semiconductor Layers
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Solution Overview
Problem
Existing back-emitting light emitting devices face challenges in achieving high laser oscillation characteristics and reliability due to laser light absorption by the substrate and high crystal defect densities in the semiconductor stacked body.
Innovation Solution
The device is manufactured by growing the semiconductor stacked body on a substrate different from the semi-insulating substrate and then joining them with a first semiconductor layer in between, creating a non-continuous lattice plane to reduce crystal defect density and minimize substrate absorption of laser light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor stacked body is grown directly on the semi-insulating substrate, then the manufacturing process is simpler, but the crystal defect density increases and laser oscillation characteristics deteriorate
Solution Approach 1:
The manufacturing process is segmented into distinct stages: growing the semiconductor stacked body on a sacrificial substrate, forming the first semiconductor layer, and then bonding to the semi-insulating substrate. This segmentation allows each stage to be optimized independently, achieving high crystal quality without excessive process complexity.
Solution Approach 2:
The first semiconductor layer acts as an intermediary between the semiconductor stacked body and the semi-insulating substrate. It facilitates bonding while maintaining the low defect density of the stacked body, resolving the contradiction between process simplicity and crystal quality.
2Reliability
If the semiconductor stacked body is grown on a different substrate and joined with a semiconductor layer, then crystal defect density decreases, but the manufacturing process becomes more complex
Solution Approach 1:
The semiconductor stacked body is preliminarily grown on a suitable substrate where optimal crystal conditions can be achieved. This preliminary action on a dedicated growth substrate enables high crystal quality before the final assembly with the semi-insulating substrate.
Solution Approach 2:
The first semiconductor layer serves as a mediator that enables the connection between the preliminarily grown stacked body and the semi-insulating substrate, allowing the complex process to yield superior crystal quality.
3Reliability
If the substrate absorbs laser light, then the device structure is simpler, but the laser oscillation characteristics and reliability deteriorate
Solution Approach 1:
The function of light transmission is extracted from the substrate by using a semi-insulating substrate with low light absorption. This extraction allows the substrate to serve its mechanical and electrical functions while the optical function is preserved for the laser cavity.
Solution Approach 2:
Different parts of the device have different optical properties: the semi-insulating substrate has low absorption for back-emission, while the semiconductor stacked body and first semiconductor layer form the active laser region with appropriate optical characteristics for oscillation.
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 laser oscillation characteristics and increases the reliability of the light emitting device by reducing crystal defects and allowing laser light emission from the back surface of the semi-insulating substrate.
Implementation Method 1
a first semiconductor layer that is stacked on the first surface of the semi-insulating substrate and has a lattice plane non-continuous to the semi-insulating substrate
Implementation Method 2
This causes the substrate to absorb less laser light
Data Source
AI summary
A light emitting device according to an embodiment of the present disclosure includes: a semi-insulating substrate having a first surface and a second surface that are opposed to each other; a first semiconductor layer that is stacked on the first surface of the semi-insulating substrate and has a lattice plane non-continuous to the semi-insulating substrate; and a semiconductor stacked body that is stacked above the first surface of the semi-insulating substrate with the semiconductor layer interposed in between. The first semiconductor layer has a first electrical conduction type. The semiconductor stacked body has a light emitting region configured to emit laser light.