Charge-Blocking Layer for GaN HEMT Leakage and RDSON Control
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Solution Overview
Problem
High Electron Mobility Transistors (HEMTs) using Group III nitride semiconductors face issues with vertical and lateral leakage currents due to lattice mismatch and doping, which can lead to dynamic RDSON effects, current collapse, and threshold voltage shifts, particularly when carbon-doped buffer structures introduce trap centers.
Innovation Solution
Incorporating a charge-blocking layer between the heterojunction and the buffer structure, configured to prevent charges from entering the buffer, and using an intentionally doped superlattice laminate to reduce leakage currents and dynamic RDSON effects, while maintaining reasonable blocking conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a carbon-doped buffer structure is used to reduce leakage currents, then leakage current is reduced, but trap centers are introduced causing dynamic RDSON effects and current collapse
Solution Approach 1:
An undoped or lightly-doped AlGaN blocking layer is introduced as an intermediary between the carbon-doped buffer and the GaN channel layer. This blocking layer acts as a mediator that prevents charges from the doped buffer from entering the channel region, thereby eliminating dynamic RDSON effects while allowing the doped buffer to continue suppressing leakage currents.
Solution Approach 2:
The buffer structure is segmented into multiple regions with different doping profiles: a carbon-doped superlattice laminate region for leakage suppression, an undoped/lightly-doped blocking layer for charge isolation, and intentionally doped GaN layers for channel formation. This segmentation allows each region to perform its specific function without interfering with others.
2Reliability
If an intentionally doped buffer structure is used to improve electrical performance, then electrical performance is improved, but charges enter the buffer causing dynamic RDSON effects
Solution Approach 1:
The undoped or lightly-doped AlGaN blocking layer serves as a charge barrier that prevents charges from the intentionally doped buffer from migrating into the channel region. This intermediary layer maintains the electrical performance benefits of the doped buffer while blocking the harmful charge migration that causes dynamic RDSON effects.
Solution Approach 2:
Different regions of the device structure are assigned different doping qualities: the buffer region is intentionally doped for electrical performance, the blocking layer is undoped or lightly-doped for charge isolation, and the channel layers are intentionally doped for carrier supply. This local differentiation of doping quality allows each region to optimize its specific function.
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 suppresses dynamic RDSON effects and reduces leakage currents, improving the performance of HEMT devices by preventing charge trapping and dislocation-induced defects, thereby enhancing the transistor's operational stability and efficiency.
Implementation Method 1
a second Group III nitride layer arranged on the first Group III nitride layer forming a heterojunction therebetween
Implementation Method 2
The blocking layer is configured to block charges from entering the buffer structure
Data Source
AI summary
In an embodiment, a method includes forming an intentionally doped superlattice laminate on a support substrate, forming a Group III nitride-based device having a heterojunction on the superlattice laminate layer, and forming a charge blocking layer between the heterojunction and the superlattice laminate.