Graded AlGaN Buffer Doping for Epitaxial Quality
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving preferable epitaxial quality due to lattice structure differences between GaN or AlGaN semiconductor layers and substrates, affecting electron-hole combination and electron stop efficiency.
Innovation Solution
A nitrogen-containing semiconductor device is designed with a substrate, a first AlGaN buffer layer doped with oxygen or carbon, a second AlGaN buffer layer, and optionally a third AlGaN buffer layer, providing a graded Al composition to alleviate interface stress and facilitate epitaxial growth, with specific thickness ranges and doping concentrations to optimize lattice structure and epitaxial quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitrogen-containing quaternary AlxInyGa1-x-yN semiconductor layer is disposed between an active layer and a P-type semiconductor layer to facilitate electron-hole combination and stop electrons, then the device performance is improved, but the epitaxial quality is deteriorated due to lattice structure differences between GaN/AlGaN layers and substrate
Solution Approach 1:
The patent introduces an AlGaN buffer layer as an intermediary between the substrate and the nitrogen-containing quaternary semiconductor layer. This buffer layer has a lattice structure that gradually transitions from the substrate to the active layer, mediating the lattice mismatch and reducing dislocation density. The buffer layer composition is carefully controlled with aluminum content ranging from 0.05 to 0.5, creating a graded structure that facilitates epitaxial growth while maintaining device performance.
Solution Approach 2:
The patent employs parameter changes by varying the aluminum content in the AlGaN buffer layer to optimize both epitaxial quality and device performance. The aluminum composition is specifically controlled within the range of 0.05 to 0.5, and the buffer layer thickness is optimized between 10-100 nm. These parameter adjustments allow the buffer layer to effectively manage lattice mismatch while enabling high-quality growth of the nitrogen-containing semiconductor layer.
2Manufacturing precision
If the lattice structure difference between GaN or AlGaN semiconductor layer and substrate is considered, then the epitaxial quality can be maintained, but the interface stress increases affecting device performance
Solution Approach 1:
The patent utilizes parameter changes by optimizing the aluminum content in the AlGaN buffer layer within the specific range of 0.05 to 0.5. This controlled variation in composition allows the buffer layer to gradually accommodate the lattice mismatch between the substrate and the active layer, thereby reducing interface stress while maintaining high epitaxial quality. The gradual composition change prevents sudden stress concentration at interfaces.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different compositions: the substrate, the AlGaN buffer layer with graded aluminum content, and the nitrogen-containing quaternary semiconductor layer. This composite material approach allows each layer to be optimized for its specific function while working together to reduce overall interface stress and improve epitaxial quality throughout the structure.
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 device achieves improved epitaxial quality by reducing interface stress and facilitating desirable semiconductor stacking, enhancing the performance of semiconductor devices such as LEDs and power devices.
Implementation Method 1
The first AlGaN buffer layer is doped with at least one of oxygen having a concentration greater than 5×10^17 cm^−3 and carbon having a concentration greater than 5×10^17 cm^−3
Data Source
AI summary
A nitrogen-containing semiconductor device including a substrate, a first AlGaN buffer layer, a second AlGaN buffer layer and a semiconductor stacking layer is provided. The first AlGaN buffer layer is disposed on the substrate, and the second AlGaN buffer layer is disposed on the first AlGaN buffer layer. A chemical formula of the first AlGaN buffer layer is AlxGa1-xN, wherein 0≤x≤1. The first AlGaN buffer layer is doped with at least one of oxygen having a concentration greater than 5×1017 cm−3 and carbon having a concentration greater than 5×1017 cm−3. A chemical formula of the second AlGaN buffer layer is AlyGa1-yN, wherein 0≤y≤1. The semiconductor stacking layer is disposed on the second AlGaN buffer layer.