Blue Laser Electron Barrier Surface Structure for Overflow Suppression
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Solution Overview
Problem
Existing blue semiconductor lasers face issues with electron overflow leading to decreased light emission efficiency, temperature characteristics deterioration, and production yield loss due to lattice strain and mechanical faults from high AlGaN electron barrier layers.
Innovation Solution
A laser element design featuring a recessed and projecting shape on the electron barrier layer with specific height and interval dimensions, formed of a group III nitride semiconductor with a higher Al composition, to prevent electron overflow and relieve lattice strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentration p-type doping is applied in the electron barrier layer to suppress electron overflow, then electron overflow is prevented, but threshold current deteriorates due to optical loss of dopants
Solution Approach 1:
The electron barrier layer is designed with non-uniform Al composition distribution, creating regions of different electron barrier heights. The Al composition ratio varies within the layer to optimize both electron confinement and reduce dopant optical loss in specific regions, rather than using uniform high concentration doping throughout.
Solution Approach 2:
The patent changes the Al composition ratio parameter within the electron barrier layer to control the electron barrier height. By adjusting the Al composition ratio to be higher than the second semiconductor layer but optimized within a specific range, the electron overflow is suppressed while minimizing the adverse effects of high concentration doping on threshold current.
2Reliability
If high concentration p-type doping is applied in the electron barrier layer to suppress electron overflow, then electron overflow is prevented, but voltage deteriorates
Solution Approach 1:
The electron barrier layer employs local quality variation through non-uniform Al composition distribution. This allows the barrier to provide strong electron confinement where needed while reducing dopant concentration in regions where high doping would cause excessive voltage deterioration, achieving a balance between electron overflow suppression and voltage maintenance.
3Reliability
If electron barrier layer is provided to suppress electron overflow, then electron overflow is prevented, but high stress is generated due to lattice strain causing unintended minute faults
Solution Approach 1:
The electron barrier layer is designed with spatially varying Al composition to create local regions with different strain characteristics. This non-uniform composition distribution allows the layer to suppress electron overflow while reducing the accumulation of lattice strain that would otherwise lead to unintended minute faults during laser cleavage.
Solution Approach 2:
By changing the Al composition ratio parameter within the electron barrier layer, the patent optimizes the balance between electron barrier height and lattice strain. The Al composition is controlled to be higher than the second semiconductor layer but within an optimized range that minimizes stress accumulation while maintaining effective electron confinement.
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
Prevents electron overflow and mechanical faults, maintaining laser characteristics and improving production yield by reducing stress and optical loss.
Implementation Method 1
an electron barrier layer which is provided between the active layer and the second semiconductor layer and is formed of a group iii nitride semiconductor having a composition ratio of Al larger than that of the second semiconductor layer
Implementation Method 2
a recessed and projecting shape being formed on a surface of the electron barrier layer on a side of the second semiconductor layer, the recessed and projecting shape having a height difference between a projecting portion and a recessed portion in a direction perpendicular to a layer surface direction being 2 nm or more and less than 10 nm
Data Source
AI summary
Provided is a laser element that includes a first semiconductor layer, a second semiconductor layer, an active layer, and an electron barrier layer. The first semiconductor layer includes a group iii nitride semiconductor having a first conductive type. The second semiconductor layer includes a group iii nitride semiconductor having a second conductive type. The electron barrier layer is between the active layer and the second semiconductor layer and includes a group iii nitride semiconductor having a composition ratio of Al larger than that of the second semiconductor layer. The electron barrier layer has a recessed and projecting shape on a surface of the electron barrier layer. The recessed and projecting shape has a height difference, between a projecting portion and a recessed portion in a direction perpendicular to a layer surface direction, that is 2 nm or more and less than 10 nm.