HEMT Buffer Doping Profile for Breakdown Voltage and Mobility
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Solution Overview
Problem
Existing high electron mobility transistors (HEMTs) face challenges in improving breakdown voltage without compromising operational efficiency, particularly due to the influence of carbon doping on the buffer layer.
Innovation Solution
A high electron mobility transistor design that includes a substrate, nucleation layer, buffer layer, channel layer, and barrier layer, where the buffer layer is doped with carbon and iron, with a specific concentration gradient of iron in the third buffer region to minimize its impact on the two-dimensional electron gas in the channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon doping is performed on the buffer layer to improve breakdown voltage, then the breakdown voltage is improved, but the operational efficiency deteriorates
Solution Approach 1:
The buffer layer is divided into three distinct buffer regions (first, second, and third buffer regions) with progressively different carbon doping concentrations. The first buffer region has the highest carbon concentration for maximum breakdown voltage enhancement, the second buffer region has intermediate concentration, and the third buffer region has the lowest concentration to minimize negative effects on operational efficiency. This segmentation allows each region to optimize its local function while contributing to overall device performance.
Solution Approach 2:
Different regions of the buffer layer are assigned different carbon doping concentrations tailored to their specific functional requirements. The first buffer region near the substrate receives high carbon doping for breakdown voltage improvement, while the third buffer region adjacent to the channel layer receives low carbon doping to preserve electron mobility and operational efficiency. This local quality differentiation resolves the contradiction by applying carbon doping selectively where it provides benefit without compromising overall device operation.
2Strength
If high carbon concentration is used in the buffer layer to enhance breakdown voltage, then the breakdown voltage increases, but the electron mobility in the channel layer deteriorates
Solution Approach 1:
The buffer layer is segmented into three regions with carbon concentrations that decrease from the first to the third buffer region. The first buffer region uses high carbon concentration (e.g., 1×10^19 to 1×10^21 atoms/cm³) to provide breakdown voltage enhancement, while the third buffer region uses low carbon concentration (e.g., 1×10^17 to 1×10^19 atoms/cm³) to minimize electron scattering and preserve electron mobility in the adjacent channel layer.
Solution Approach 2:
Carbon doping concentration is locally optimized in each buffer region according to its position and function. The first buffer region near the substrate is doped heavily for electrical isolation and breakdown voltage improvement, while the third buffer region near the channel is lightly doped to maintain high electron mobility. This local quality approach ensures that carbon doping provides breakdown voltage enhancement without adversely affecting channel electron transport.
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
This design effectively enhances the breakdown voltage while maintaining operational efficiency by carefully managing the carbon and iron doping concentrations, particularly through the controlled gradient of iron in the buffer regions.
Implementation Method 1
doping is generally performed on a buffer layer of the HEMT. For example, by performing carbon doping on the buffer layer, the breakdown voltage of the HEMT could be effectively improved
Data Source
AI summary
A high electron mobility transistor includes a substrate, a nucleation layer, a buffer layer, a channel layer, and a barrier layer. The buffer layer includes a first buffer region, a second buffer region and a third buffer region. The first buffer region includes a first III-nitride stacked layer disposed on the nucleation layer and a second III-nitride stacked layer disposed on the first III-nitride stacked layer. The second buffer region is doped with carbon and iron. The third buffer region is doped with carbon and iron and has a carbon concentration greater than an iron concentration of the third buffer region. The second III-nitride stacked layer is doped with carbon and iron and has a carbon concentration greater than an iron concentration of the second III-nitride stacked layer.