Ridge Optical Semiconductor Electrode Layout for Low Parasitic Capacitance
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Solution Overview
Problem
Ridge type semiconductor optical devices with mesa stripe structures face challenges in reducing parasitic capacitance, which hinders high-speed operation, and placing electrodes on narrow mesa stripe structures is difficult due to their narrow width.
Innovation Solution
The design includes an isolation groove that separates the active layer, a mesa stripe structure, and a bank structure, with an electrode pattern that extends along the side of the mesa stripe structure and connects to a pad electrode, while maintaining a narrow connection electrode width to minimize parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the upper electrode extends to the top of the bank structure, then the electrode can be easily manufactured, but the parasitic capacitance increases and high-speed operation is prevented
Solution Approach 1:
The electrode is divided into multiple segments: a first electrode on the mesa stripe structure, a second electrode on the bank structure, and a connection electrode connecting them. The connection electrode has a reduced width in the first direction compared to the other electrodes, segmenting the current path to reduce parasitic capacitance while maintaining manufacturing feasibility.
2Reliability
If the electrodes are placed only on the top of the mesa stripe structure, then the parasitic capacitance is reduced, but the manufacturing difficulty increases due to the narrow width
Solution Approach 1:
The electrode structure utilizes multiple dimensions by extending electrodes not only on the top surface but also on the side surfaces of the mesa stripe structure and bank structure. This three-dimensional electrode configuration allows current injection from multiple directions, reducing parasitic capacitance while maintaining ease of manufacture through extended contact areas.
3Ease of manufacture
If the connection electrode has the same width as the ridge and pad electrodes, then the manufacturing is simpler, but the parasitic capacitance increases
Solution Approach 1:
Different parts of the electrode structure have different widths optimized for their specific functions. The connection electrode has a narrower width in the first direction compared to the ridge and pad electrodes, locally reducing parasitic capacitance where it is most critical, while other electrodes maintain wider dimensions for adequate current carrying capacity and manufacturing tolerance.
Data Source
AI summary
A device includes: a laminate including first and second regions adjacent to respective both sides of an isolation groove; a mesa stripe structure adjacent to the first region on the laminate and extending in the first direction; a bank structure adjacent to the second region on the laminate and extending in the first direction; and an electrode pattern. The isolation groove has an inner surface including a first wall surface adjacent to the first region, a second wall surface adjacent to the second region, and a bottom surface between the first and second regions. The ridge electrode extends from the side of the mesa stripe structure, along a second direction, toward the bank structure, and not beyond the second wall surface. The connection electrode is narrower in width in the first direction than any one of the ridge electrode and the pad electrode.