Semiconductor Optical Layer Structure for p-Type Clad Crystallinity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor optical elements, such as laser diodes, face issues with reduced crystallinity in p-type compound semiconductor clad layers due to the etching action of halomethane raw materials used in the MOCVD method, leading to poor light emission characteristics and reliability.
Innovation Solution
A semiconductor optical element structure is developed with a carbon-doped p-type semiconductor layer positioned closer to the active layer than a group 2 element-doped p-type semiconductor layer, reducing the thickness of the carbon-doped layer while maintaining the required thickness of the p-type clad layer, which improves crystallinity and light emission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon is used as a p-type dopant in the p-type clad layer to prevent carbon diffusion and lower threshold current density, then the reliability and threshold current density are improved, but the crystallinity of the p-type clad layer is lowered
Solution Approach 1:
The p-type clad layer is divided into multiple sub-layers with different carbon concentrations. The first p-type clad layer has a lower carbon concentration than the second p-type clad layer, creating a gradient structure that reduces the harmful etching effect on crystallinity while maintaining the overall p-type doping function for reliability improvement.
Solution Approach 2:
Different regions of the p-type clad layer are assigned different carbon concentrations based on their functional requirements. The region closer to the active layer has lower carbon concentration to preserve crystallinity, while the outer region has higher carbon concentration to provide sufficient p-type doping for reliability and threshold current density control.
2Reliability
If the concentration of carbon dopant in the p-type clad layer is increased to improve reliability, then the threshold current density is lowered, but the crystallinity is further reduced
Solution Approach 1:
The p-type clad layer is segmented into multiple layers with progressively increasing carbon concentrations from the active layer interface outward. This segmentation allows the total carbon dose to be distributed, achieving the required reliability improvement without concentrating excessive carbon in one layer that would cause severe crystallinity degradation.
Solution Approach 2:
The carbon concentration parameter is varied spatially across the p-type clad layer thickness. By changing the carbon concentration from one layer to the next, the patent achieves a balance between obtaining sufficient p-type doping for reliability while controlling the local carbon concentration to maintain acceptable crystallinity in each layer.
3Stability of the object's composition
If the thickness of the p-type clad layer is increased to maintain required optical confinement, then the light emission characteristics deteriorate due to roughness and lowered crystallinity
Solution Approach 1:
The thick p-type clad layer is divided into multiple thinner sub-layers, each with controlled carbon concentration. This segmentation prevents the formation of surface roughness that would occur in a single thick layer with high carbon concentration, while still achieving the required total thickness for optical confinement and overall reliability improvement.
Solution Approach 2:
Each sub-layer within the p-type clad structure has locally optimized carbon concentration and thickness. This local quality control ensures that no single layer develops excessive roughness or crystallinity degradation, while the cumulative effect of multiple layers provides the necessary total thickness for proper optical confinement and reliability.
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 configuration enhances light emission characteristics and long-term reliability by suppressing dopant diffusion and reducing surface roughness, allowing for higher dopant concentrations in the carbon-doped layer without compromising crystallinity.
Implementation Method 1
suppressing dopant diffusion
Implementation Method 2
manufacturing a GaAs-based semiconductor laser by an organic metal vapor phase growth method (MOCVD method)
Data Source
AI summary
A semiconductor optical element includes: a first conductivity type semiconductor substrate; and a laminated body disposed on the first conductivity type semiconductor substrate. The laminated body includes, in the following order from a side of the first conductivity type semiconductor substrate: a first conductivity type semiconductor layer; an active layer; a second conductivity type semiconductor layer; and a second conductivity type contact layer. The second conductivity type semiconductor layer includes: a carbon-doped semiconductor layer in which carbon is doped as a dopant in a compound semiconductor; and a group 2 element-doped semiconductor layer in which a group 2 element is doped as a dopant in a compound semiconductor. The carbon-doped semiconductor layer is disposed at a position closer to the active layer than the group 2 element-doped semiconductor layer.