Nitride Semiconductor Gate Barrier for High-Temperature Bias Stability
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Solution Overview
Problem
Semiconductor devices with direct bandgap materials face reliability issues under high temperature reverse bias and gate bias due to hole extraction and accumulation, leading to irreversible threshold voltage shifts and increased leakage current.
Innovation Solution
Incorporating a barrier layer with a bandgap greater than AlGaN between the gate structure and nitride semiconductor layers to restrain hole extraction and accumulation, enhancing the reliability of the semiconductor device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate structure is directly contacted with nitride semiconductor layers, then device operation is enabled, but hole extraction and accumulation occur leading to threshold voltage shifts and increased leakage current under high temperature conditions
Solution Approach 1:
A barrier layer with greater bandgap than AlGaN is introduced between the gate structure and the nitride semiconductor layers. This intermediary layer prevents direct contact, thereby restraining hole extraction and accumulation at the gate-semiconductor interface while maintaining device operation. The barrier layer acts as a mediator that blocks harmful hole transport without compromising the gate's control function.
Solution Approach 2:
The device structure employs a composite material approach by combining the barrier layer (with higher bandgap) and AlGaN layer (with lower bandgap) in a layered configuration. This composite structure leverages the different bandgap properties of the materials to create an effective hole barrier while maintaining the necessary electrical characteristics for device operation.
2Reliability
If AlGaN layers are used in the device structure, then good electrical performance is achieved, but hole accumulation occurs at the interface under high temperature bias conditions
Solution Approach 1:
The barrier layer serves as an intermediary between the gate and AlGaN layers, preventing holes from accumulating at the AlGaN interface under high temperature bias. This intermediary structure maintains the electrical performance benefits of AlGaN while eliminating the harmful interface accumulation effect.
Solution Approach 2:
The barrier layer is strategically positioned only at the critical gate interface region where hole accumulation occurs. This localized approach maintains the excellent electrical properties of AlGaN in the bulk regions while providing hole blocking protection specifically where needed at the interface.
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 barrier layer effectively prevents hole accumulation and extraction, maintaining a stable threshold voltage and reducing leakage current under high temperature conditions, thereby enhancing the reliability of semiconductor devices like HEMT devices.
Implementation Method 1
The barrier layer is in contact with the third nitride semiconductor layer and has a bandgap greater than that of the second nitride semiconductor layer
Data Source
AI summary
Semiconductor device structures and methods for manufacturing the same are provided. The semiconductor device structure includes a substrate, a first nitride semiconductor layer, a second nitride semiconductor layer, a barrier layer, a third nitride semiconductor layer and a gate structure. The first nitride semiconductor layer is disposed on the substrate. The second nitride semiconductor layer is disposed on the first nitride semiconductor layer and has a bandgap greater than that of the first nitride semiconductor layer. The barrier layer is disposed on the second nitride semiconductor layer and has a bandgap greater than that of the second nitride semiconductor layer. The third nitride semiconductor layer is doped with impurity and disposed on the barrier layer. The gate structure is disposed on the third nitride semiconductor layer.