Semiconductor Laser Element with Diffusion Barrier Layer
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Solution Overview
Problem
Conventional VCSEL elements experience an increase in driving voltage due to the diffusion of metal electrodes into semiconductor layers, leading to increased element resistance and optical output degradation.
Innovation Solution
A semiconductor laser element with a first semiconductor layer between the electrode and the high-doping second semiconductor layer, where the electrode components diffuse into the first layer, preventing further diffusion through the second layer and maintaining a larger contact area, thus reducing resistance and maintaining optical output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode is placed to contact the high-doping second semiconductor layer directly, then current injection efficiency is improved, but metal components diffuse into the semiconductor layer causing increased element resistance and driving voltage
Solution Approach 1:
A first semiconductor layer with lower doping concentration is introduced as an intermediary layer between the metal electrode and the high-doping second semiconductor layer. This intermediate layer allows the electrode to contact the semiconductor structure without direct diffusion of metal components into the high-doping region, thereby maintaining current injection efficiency while preventing resistance increase from metal contamination.
2Object-affected harmful factors
If the electrode contacts the first semiconductor layer in the second region, then metal diffusion is prevented, but contact area is reduced potentially increasing resistance
Solution Approach 1:
The first semiconductor layer is designed with spatially varying doping concentration, having a lower doping concentration region (second region) where the electrode contacts to prevent diffusion, and a higher doping concentration region (first region) facing the current confinement layer to ensure good electrical contact. This local quality variation allows the same layer to simultaneously prevent metal diffusion while maintaining low contact resistance.
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
The solution effectively suppresses the increase in driving voltage and maintains optical output by ensuring a stable contact area with the high-doping second semiconductor layer, while preventing excessive diffusion and resistance increase.
Implementation Method 1
The first semiconductor layer has a diffusion portion where a component of the first electrode or at least a part of components of the first electrode diffuses into at least the first semiconductor layer
Implementation Method 2
a current confinement layer confining a path of a current flowing between the first electrode and the second electrode and having a first region in which the current flows and a second region that blocks a flow of the current
Data Source
AI summary
A semiconductor laser element includes a first electrode, a second electrode, a first reflecting mirror, a second reflecting mirror, and a resonator. The resonator includes an active layer, a current confinement layer, a first semiconductor layer having a first doping concentration formed at a side opposite to the active layer across the current confinement layer, and a second semiconductor layer having a second doping concentration higher than the first doping concentration formed between the first semiconductor layer and the current confinement layer. The first electrode is provided to contact a part of a surface of the first semiconductor layer. The first semiconductor layer has a diffusion portion into which a component of the first electrode diffuses. The second semiconductor layer contacts the diffusion portion. The second semiconductor layer is positioned at a node of a standing wave at a time of laser oscillation of the semiconductor laser element.