Surface Emitting Semiconductor Laser Mesa Segmentation
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Solution Overview
Problem
Surface emitting semiconductor lasers face issues with heat dissipation and increased resistance due to small semiconductor mesa sizes, leading to reduced optical output power and modulation band narrowing, and high parasitic capacitance from ion implantation for current confinement.
Innovation Solution
A surface emitting semiconductor laser design with a low-resistance and high-resistance region optical cavity mesa, where the high-resistance region is formed by ion-implanted hydrogen or oxygen, and the tunnel junction region is positioned to minimize resistance and parasitic capacitance, with a passivation film covering the optical cavity mesa and electrodes strategically placed to reduce capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the semiconductor mesa size is decreased to reduce parasitic capacitance, then parasitic capacitance is reduced, but heat dissipation becomes insufficient and temperature increases
Solution Approach 1:
The semiconductor mesa is segmented into multiple regions with different resistance characteristics. A low-resistance region is formed at the center to improve heat dissipation, while high-resistance regions are formed at the periphery to confine current. This segmentation allows the small mesa structure to maintain low parasitic capacitance while improving heat dissipation through the low-resistance center region.
Solution Approach 2:
Different regions of the semiconductor mesa are given different electrical properties. The central region has low resistance to facilitate heat dissipation and current flow, while the peripheral regions have high resistance to confine current. This local differentiation of electrical properties allows the structure to simultaneously reduce capacitance and improve heat dissipation.
2Reliability
If ion implantation is used to form high-resistance regions for current confinement, then current confinement is improved, but device resistance increases
Solution Approach 1:
Ion implantation is applied selectively to specific regions of the semiconductor mesa to create high-resistance zones only where current confinement is needed at the periphery. The central region remains low-resistance to maintain low overall device resistance. This localized application of ion implantation achieves current confinement without significantly increasing device resistance.
Solution Approach 2:
The patent uses ion implantation to create a replicated high-resistance region structure that mirrors the desired current confinement pattern. By implanting ions in specific geometric patterns, the high-resistance regions are formed as copies of the confinement zones needed, achieving reliable current confinement while controlling overall resistance.
3Device complexity
If the semiconductor mesa size is decreased, then parasitic capacitance is reduced, but optical output power decreases due to poor heat dissipation
Solution Approach 1:
The semiconductor mesa is segmented into low-resistance and high-resistance regions, with the low-resistance central region serving as an efficient heat dissipation path. This segmentation enables the small mesa to maintain low capacitance while the low-resistance region ensures adequate heat dissipation to sustain optical output power.
Solution Approach 2:
The electrical resistance parameters of different mesa regions are changed through selective ion implantation. The central region maintains low resistance to ensure heat dissipation and optical output power, while peripheral regions have high resistance for current confinement. This parameter differentiation allows the small structure to achieve both low capacitance and sufficient power output.
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 design enhances heat dissipation, reduces device resistance, and maintains low parasitic capacitance, preventing saturation of optical output and improving the modulation band without increasing parasitic capacitance.
Implementation Method 1
ions are implanted into the outer region. The ion implantation can provide a part of the p-type semiconductor mirror with high-resistance, and this part of high-resistance confines electric current.
Implementation Method 2
A semiconductor mesa is provided on the distributed Bragg reflector and includes an active layer, a tunnel junction region
Data Source
AI summary
In a surface emitting semiconductor laser, the primary surface of a substrate includes first to third areas. The first and second areas are contiguous to each other, and the third area surrounds the first and second areas. A first DBR is provided on the substrate. An active layer is provided on the following: the first DBR; the first and second areas; and a boundary therebetween. A first semiconductor spacer layer is provided on the active layer. A second semiconductor spacer layer is provided on the first semiconductor spacer layer. The conductivity type of the first semiconductor spacer layer is different from that of the second semiconductor spacer layer. A tunnel junction region is on the first area and between the first and the second semiconductor spacer layers. The active layer, the first semiconductor spacer layer, the second semiconductor spacer layer, the tunnel junction region constitutes an optical cavity mesa, which includes low-resistance and high-resistance regions located on the first area and the second area, respectively. The low-resistance region includes the tunnel junction region. A second DBR is on the second semiconductor spacer layer and the first area. A first electrode is on the first and second areas and the boundary.