Semiconductor Laser Cladding Structure for Impurity Diffusion Blocking
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Solution Overview
Problem
In semiconductor lasers, impurities diffused from electrodes can form crystal defects near the active layer, degrading light-emitting characteristics.
Innovation Solution
A semiconductor device with a diffusion prevention layer of a conductivity type different from the cladding layer is provided to trap impurities at the pn interface, preventing them from reaching the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back surface electrode is formed on the entire surface of the semiconductor laser, then the electrical connection is improved, but the diffusion of impurities from the electrode to the active layer is increased
Solution Approach 1:
An n-type diffusion prevention layer is introduced as an intermediary between the back surface electrode and the active layer. This layer acts as a barrier that prevents impurities (particularly Zn) from diffusing through the electrode to the active layer, while still allowing the electrode to maintain its electrical connection function across the entire surface.
Solution Approach 2:
The semiconductor laser structure is segmented into distinct functional layers: the back surface electrode layer, the n-type diffusion prevention layer, the n-type cladding layer, and the active layer. This segmentation allows each layer to perform its specific function independently - the electrode provides electrical connection while the diffusion prevention layer blocks impurity migration.
2Ease of manufacture
If impurities are incorporated into the electrode, then the electrode formation is simplified, but the light-emitting characteristics are degraded due to impurity diffusion
Solution Approach 1:
The n-type diffusion prevention layer serves as a protective intermediary between the electrode and the active layer. This allows the electrode to be formed with impurities incorporated during the electrode fabrication process without compromising the light-emitting characteristics, as the diffusion prevention layer blocks the impurities from reaching the active layer.
Solution Approach 2:
The presence of impurities in the electrode, which would normally be harmful, is converted into a non-problematic condition by introducing the diffusion prevention layer. The impurities are effectively trapped in the electrode or diffusion prevention layer, preventing them from degrading the active layer's light-emitting properties.
3Object-affected harmful factors
If a diffusion prevention layer is provided between the cladding layer and active layer, then impurity diffusion is prevented, but the device structure becomes more complex
Solution Approach 1:
The n-type diffusion prevention layer performs multiple functions simultaneously: it prevents impurity diffusion from the electrode to the active layer, maintains the n-type conductivity type consistent with the surrounding cladding layers, and provides a continuous protective barrier across the entire device area. This multi-functionality justifies the additional layer despite the increased structural complexity.
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 impurities from accumulating in the active layer, thereby maintaining the light-emitting characteristics and efficiency of the semiconductor device.
Implementation Method 1
a pn interface between the cladding layer and the diffusion prevention layer, and trap the ionized impurities from the back surface electrode at the pn interface
Data Source
AI summary
A semiconductor device according to the present application includes a semiconductor substrate, an n-type first cladding layer provided on the semiconductor substrate, an n-type second cladding layer provided on the first cladding layer, an active layer provided on the second cladding layer, a p-type third cladding layer provided on the active layer, a surface electrode provided above the third cladding layer, a back surface electrode provided below the semiconductor substrate and a p-type diffusion prevention layer provided between the first cladding layer and the second cladding layer.