Semiconductor Laser Ridge Electrode Barrier Against Solder Diffusion
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Solution Overview
Problem
The diffusion of solder components into the electrode layer of semiconductor lasers degrades their long-term reliability, particularly in edge-emitting semiconductor lasers where the solder is used to fix the laser to a heat exhaust member.
Innovation Solution
The semiconductor laser design includes a pad metal layer on the ridge side, separated from the resonator end faces and covered by a barrier metal layer, preventing solder diffusion into the electrode layer, and a bonding metal layer also separated from the end faces, reducing stress and further suppressing solder diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a solder is used to fix the semiconductor laser to the heat exhaust member, then heat dissipation is improved, but solder components diffuse into the electrode layer degrading long-term reliability
Solution Approach 1:
The patent introduces a barrier layer as an intermediary between the solder and the electrode layer. This barrier layer prevents direct contact and diffusion between solder components and the electrode layer, while still allowing thermal energy to pass through to the heat exhaust member. The barrier layer thus mediates between the conflicting requirements of heat dissipation and reliability protection.
Solution Approach 2:
The electrode layer is segmented into multiple functional layers: a lower electrode layer for electrical connection, a barrier layer for diffusion prevention, and an upper electrode layer for solder bonding. This segmentation allows each layer to perform its specific function independently, enabling simultaneous achievement of electrical conductivity, diffusion barrier, and heat dissipation.
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 effectively suppresses solder diffusion, enhancing the long-term reliability of the semiconductor laser by preventing degradation of the electrode layer and maintaining stable operation.
Implementation Method 1
The second metal layer covers the entire surface of the first metal layer, and suppresses the diffusion of a component of the solder into the first metal layer
Data Source
AI summary
A semiconductor laser according to one embodiment of the present disclosure includes: a first semiconductor layer of a first conductivity type; an active layer; and a second semiconductor layer of a second conductivity type stacked on the first semiconductor layer with the active layer interposed therebetween, and provided with a strip-shaped ridge. The semiconductor laser further includes: a pair of resonator end faces facing each other across the ridge; and an electrode layer electrically coupled to an upper surface of the ridge.