Doped Nitride Buffer Epitaxial Structure for HEMT Voltage Resistance
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Solution Overview
Problem
Conventional epitaxial structures with aluminum-based buffer layers in High Electron Mobility Transistors (HEMTs) exhibit poor voltage resistance, necessitating a solution for stress adjustment and enhanced voltage resistance.
Innovation Solution
An epitaxial structure comprising a substrate, a first buffer layer with a ternary or higher nitride and element doping, a second buffer layer without aluminum and with element doping, and a channel layer, where the first buffer layer has an aluminum atom concentration less than or equal to 25% and a doping concentration greater than or equal to 1×10^18 cm^-3, and the second buffer layer has a thickness ratio greater than or equal to 1.5 and less than or equal to 10, to achieve stress adjustment and improved voltage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a conventional buffer layer containing aluminum without doping is used to adjust stress, then stress adjustment is achieved, but voltage resistance performance deteriorates
Solution Approach 1:
The buffer layer is divided into two distinct portions: a first portion with low aluminum concentration (≤25 at %) and high doping concentration (≥1×10^18 cm^-3) to provide high voltage resistance, and a second portion with high aluminum concentration (>25 at %) to provide stress adjustment. This local differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The buffer layer is constructed as a composite structure combining two different material compositions with distinct properties. The first portion uses a doped nitride material optimized for electrical performance, while the second portion uses an aluminum-rich nitride material optimized for mechanical stress control, creating a multi-functional composite layer.
2Stress or pressure
If the aluminum atom concentration in the nitride layer is increased to enhance stress adjustment, then stress control improves, but voltage resistance deteriorates
Solution Approach 1:
The buffer layer is segmented into two portions with different aluminum concentrations. The first portion maintains low aluminum concentration (≤25 at %) to preserve high voltage resistance, while the second portion contains high aluminum concentration (>25 at %) to provide effective stress control. This segmentation resolves the conflict by spatially separating the two competing requirements.
Solution Approach 2:
Different regions of the buffer layer are assigned different aluminum concentrations based on their specific functional requirements. The first portion near the channel interface has low aluminum content for electrical performance, while the second portion has high aluminum content for mechanical stress management, allowing each local region to optimize its property.
Data Source
AI summary
An epitaxial structure includes a substrate, a first buffer layer, a second buffer layer, and a channel layer, wherein the first buffer layer is located on a top of the substrate and includes a first portion. The first portion includes a nitride, which is ternary and above, and an aluminum atom concentration of the first portion is less than or equal to 25 at %. The first portion has an element doping, wherein a doping concentration of the element doping of the first portion is greater than or equal to 1×1018 cm−3. The second buffer layer is located on a top of the first buffer layer. The second buffer layer is provided without aluminum and has an element doping. The channel layer is located on a top of the second buffer layer.