Semiconductor Laser Electrode Structure for Cleavage and Moisture Resistance
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Solution Overview
Problem
The existing methods for forming an Au electrode up to the resonator end face in compound semiconductor lasers result in Au hanging during cleavage, leading to cavity formation and degraded moisture resistance due to moisture permeation.
Innovation Solution
A semiconductor laser design featuring a first Au electrode up to the resonator end face, a second Au electrode excluding the adjacent region, and a metal layer harder than Au in that region, preventing Au hanging and cavity generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an Au electrode is formed in a region of up to the resonator end face to enhance heat radiation characteristics, then heat radiation performance is improved, but the Au electrode tears off and hangs down during cleavage, causing cavity formation and degraded moisture resistance
Solution Approach 1:
The electrode structure is divided into two distinct parts: a first Au electrode layer that extends to the resonator end face for heat radiation, and a second electrode layer (different material or structure) that starts from a position away from the end face to avoid hanging during cleavage. This segmentation allows each part to fulfill its specific function without causing the hanging problem
Solution Approach 2:
Different electrode structures are applied to different regions: near the resonator end face, a Au electrode is used for optimal heat radiation, while in the cleavage region, a different electrode material or structure is used that prevents hanging during cleavage. This local differentiation resolves the contradiction between heat radiation performance and cleavability
2Ease of manufacture
If the thickness of Au electrode is reduced at the cleavage position to improve cleavability, then cleavage becomes easier, but Au still hangs over the resonator end face, resulting in cavity formation and moisture permeation
Solution Approach 1:
The problematic Au electrode is extracted or removed from the cleavage region entirely, replacing it with a different electrode material or structure that does not exhibit hanging behavior during cleavage. This extraction eliminates the root cause of the hanging problem while preserving heat radiation functionality in non-cleavage regions
3Reliability
If a coating film is formed on the resonator end face to protect it, then moisture resistance is improved, but a cavity forms between the coating film and resonator end face due to hanging Au, allowing moisture to permeate directly to inner layers
Solution Approach 1:
The hanging of Au electrode is prevented in advance by using a different electrode material or structure in the cleavage region, thereby preventing the formation of cavities before the coating film is applied. This preliminary prevention ensures that the coating film forms a continuous, cavity-free protective layer that effectively blocks moisture permeation
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 effectively suppresses Au hanging and maintains high moisture resistance by preventing cavity formation, ensuring the laser's reliability and performance.
Implementation Method 1
a metal layer formed on the first Au electrode in the region adjacent to the resonator end face and made of metal harder than Au
Implementation Method 2
a coating film formed on the resonator end face
Data Source
AI summary
A compound semiconductor multilayer (2-4) is film formed on a compound semiconductor substrate (1) and includes a ridged stripe (5) and a resonator end face (6) which corresponds to a cleavage plane perpendicular to a long-side direction of the stripe (5). A first Au electrode (8) is formed on the stripe (5) in a region of up to the resonator end face (6). A second Au electrode (9) is formed on the first Au electrode (8) in a region excluding a region adjacent to the resonator end face (6). A metal layer (10) made of metal harder than Au is formed on the first Au electrode (8) in the region adjacent to the resonator end face (6). A coating film (12) is formed on the resonator end face (6).