UV Laser Diode Mesa Electrode Layout for Lower Threshold Current
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Solution Overview
Problem
Current methods for producing ultraviolet laser diodes do not effectively achieve a low oscillation threshold current density, which is essential for efficient operation.
Innovation Solution
A method involving the stacking of conductive nitride semiconductor layers, quantum well layers, and a specific electrode configuration, where the second electrode is positioned at a distance of 5 μm or more from the side surfaces of a mesa structure, to optimize current injection and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the second electrode is disposed as close as possible to the side surface by the side of the first electrode of a mesa structure, then element resistance is reduced, but the oscillation threshold current density does not achieve the desired low value
Solution Approach 1:
The patent applies local quality by creating different electrode configurations for different regions of the laser diode. The first electrode is positioned close to the side surface to reduce resistance in that region, while the second electrode is positioned at a specific distance (5 μm or more) from the side surface to optimize the oscillation threshold current density. This spatial differentiation of electrode positions allows each region to have optimized properties for its specific function.
Solution Approach 2:
The patent changes the positional parameter of the second electrode relative to the side surface of the mesa structure. By specifying that the second electrode be disposed at a distance of 5 μm or more from the side surface, the patent optimizes the electrical and optical parameters to achieve both low element resistance and low oscillation threshold current density simultaneously.
2Reliability
If the second electrode is disposed close to the side surface to reduce element resistance, then conductivity is improved, but the oscillation threshold current density remains high
Solution Approach 1:
The patent segments the electrode system into two distinct electrodes with different positioning strategies. The first electrode is positioned close to the side surface for optimal conductivity, while the second electrode is positioned at a specific distance (5 μm or more) from the side surface to optimize oscillation characteristics. This segmentation allows independent optimization of conductivity and oscillation threshold parameters.
Solution Approach 2:
The patent introduces a dimensional parameter (distance from side surface) to differentiate the positioning of the two electrodes. By specifying the second electrode's position in terms of its distance (5 μm or more) from the side surface, the patent uses spatial dimensionality to resolve the contradiction between conductivity optimization and oscillation threshold reduction.
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 results in a significant reduction of the oscillation threshold current density, enhancing the ultraviolet laser diode's efficiency and extending its element life.
Implementation Method 1
Nitride semiconductors have a direct transition form of recombination, enabling a high recombining efficiency and high optical gain to be obtained.
Implementation Method 2
disposing first conductive material on a portion of the first area and applying heat treatment of 400° C. or higher to form a first electrode
Data Source
AI summary
A method of producing an ultraviolet laser diode with a low oscillation threshold current density includes stacking a first cladding layer, a light-emitting layer, and a second cladding layer on a substrate in this order to form a nitride semiconductor laminate (step S101), etching at least a portion of the nitride semiconductor laminate to form a mesa structure and setting the ratio between the length of the resonator end faces and the length of the side surfaces of the mesa structure in plan view between 1:5 and 1:500 (step S102), disposing first conductive material on a portion of a first area and applying heat treatment of 400° C. or higher to form a first electrode (step S103), and disposing a second conductive material in an area on the second cladding layer, at a distance of 5 μm or more from the side surfaces, to form a second electrode (step S104).