Composite Epitaxial Barrier Structure to Block Mg Diffusion
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Solution Overview
Problem
Mg ions in the p-GaN layer of semiconductor devices diffuse to the barrier and channel layers, affecting the density and mobility of two-dimensional electron gas (2DEG), leading to increased on resistance and limiting power density.
Innovation Solution
A composite barrier layer comprising a digital alloy barrier layer with AlN layers is introduced between the doping and channel layers, preventing Mg ion diffusion and maintaining electrical performance by generating a polarization effect with the channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Mg ions are doped in the p-GaN layer to implement positive drift of threshold voltage, then the hole concentration is increased, but the Mg ions massively diffuse to the barrier layer and the channel layer, affecting density and mobility of 2DEG, thereby causing an increase in on resistance
Solution Approach 1:
An AlN layer is introduced as an intermediary barrier between the p-GaN layer and the AlGaN barrier layer. This AlN layer acts as a diffusion barrier that blocks Mg ions from migrating from the p-GaN layer into the AlGaN barrier layer and channel layer, thereby preventing the harmful diffusion effect while maintaining the threshold voltage control function
Solution Approach 2:
The barrier structure is segmented into multiple functional layers: the AlGaN barrier layer for generating 2DEG, the inserted AlN layer for blocking Mg ion diffusion, and the p-GaN layer for threshold voltage control. This segmentation allows each layer to perform its specific function independently, solving the diffusion problem without compromising overall device performance
2Object-affected harmful factors
If the AlN layer is inserted between the p-GaN layer and the AlGaN barrier layer, then the Mg ion diffusion is blocked, but the device structure becomes more complex
Solution Approach 1:
Instead of creating a completely new multi-layer barrier structure, the invention uses a partial approach by inserting only a thin AlN layer (typically 1-10 nm) between the existing p-GaN and AlGaN layers. This minimal addition provides the necessary diffusion blocking function with minimal increase in structural complexity
Solution Approach 2:
The AlN layer thickness is optimized to be thin (1-10 nm) to provide sufficient Mg ion blocking capability while minimizing the impact on device performance and manufacturing complexity. By controlling the thickness parameter, the solution achieves effective diffusion prevention without excessive structural complexity
3Object-affected harmful factors
If a thin AlN layer is used as diffusion barrier, then the Mg ion diffusion is effectively blocked, but the growth rate is much lower than that of the AlGaN barrier layer, affecting production efficiency
Solution Approach 1:
The AlN layer is grown to a thin thickness (1-10 nm) which is sufficient to block Mg ion diffusion but minimizes the additional growth time required. This partial approach ensures that the diffusion blocking function is achieved without significantly impacting production efficiency
Solution Approach 2:
The thickness parameter of the AlN layer is optimized to balance diffusion blocking effectiveness with growth rate considerations. By setting the thickness in the 1-10 nm range, the solution achieves adequate Mg ion blocking while maintaining acceptable production efficiency
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 prevents Mg ion diffusion, reducing on resistance and enhancing power density while improving production efficiency and reducing costs.
Implementation Method 1
the digital alloy barrier layer and the AlGaN barrier layer are combined to prevent the Mg ions from diffusing, while effectively improving production efficiency of products and reducing production costs of products. A growth method of the digital alloy barrier layer generates extremely small stress under a same proportion of a quantity of Al atoms, thereby avoiding an inverse piezoelectric effect caused by stress in a high-temperature and high-power working condition.
Implementation Method 2
the digital alloy barrier layer that includes one or more AlN layers is disposed between the doping layer and the channel layer, which can effectively prevent Mg ions doped in the doping layer from diffusing to the composite barrier layer and the channel layer
Data Source
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AI summary
This application provides a semiconductor epitaxial structure and a semiconductor device. The semiconductor epitaxial structure includes a channel layer, a composite barrier layer, and a doping layer. The doping layer is disposed on the composite barrier layer, the channel layer is disposed on a side of the composite barrier layer that faces away from the doping layer, and the composite barrier layer includes a digital alloy barrier layer and an AlGaN barrier layer that are disposed in a laminated manner, and the digital alloy barrier layer includes one or more AlN layers. The semiconductor epitaxial structure provided in this application effectively prevents Mg ions in the p-GaN barrier layer from diffusing to the barrier layer and the channel layer, which effects a density and mobility of two-dimensional electronic gas, and causes a problem of an increase in an on resistance.