GaN Gate-Source Field Plates for Trapping and Leakage Reduction
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Solution Overview
Problem
AlGaN/GaN transistors face limitations due to electron trapping, which affects their DC and RF characteristics, particularly at high electric fields, leading to reduced reliability and performance, especially in class C and higher class operations.
Innovation Solution
The implementation of a gate-source field plate arrangement, where a field plate is placed on a spacer layer extending over the active region towards both the drain and source electrodes, reducing the peak electric field on both sides of the gate, and is electrically connected to either the source or gate, thereby reducing trapping and enhancing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high electric fields are used in AlGaN/GaN transistors to achieve high power operation, then power density and voltage operation are improved, but electron trapping increases leading to reduced reliability and performance
Solution Approach 1:
A field plate structure is introduced as an intermediary element between the gate and drain/source regions. The field plate is connected to the gate through a spacer layer and extends over the active region, serving as a mediator to distribute and reduce the peak electric field in high-field regions, thereby reducing electron trapping while maintaining high power operation capability
2Strength
If conventional gate structures are used, then device simplicity is maintained, but breakdown voltage is limited due to high peak electric fields on both sides of the gate
Solution Approach 1:
The gate structure is segmented into multiple components: the conventional gate electrode, a spacer layer, and an extended field plate structure. This segmentation allows the electric field to be distributed across multiple regions, reducing the peak field at critical interfaces and increasing breakdown voltage while maintaining manageable structural complexity
3Strength
If field plates are placed only on the drain side of the gate, then breakdown voltage is improved, but reliability deteriorates under negatively biased gate conditions due to significant electric field on the source side
Solution Approach 1:
The field plate structure is designed with different local characteristics: it extends over both the drain-side and source-side active regions, with potentially different lengths or configurations on each side. This local quality differentiation allows optimized electric field distribution for both breakdown voltage enhancement and reliability improvement under negative gate bias conditions
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 configuration increases breakdown voltage, reduces leakage currents, and enhances reliability and performance, particularly under negatively biased gate conditions, improving the transistor's robustness and stability across various operational classes.
Implementation Method 1
reducing the peak electric field on both sides of the gate
Implementation Method 2
A first spacer layer is formed above the active region, over at least a portion of the surface of the active region between the gate and the drain
Data Source
AI summary
A transistor comprising an active region having a channel layer, with source and drain electrodes formed in contact with the active region and a gate formed between the source and drain electrodes and in contact with the active region. A spacer layer is on at least part of the surface of the plurality of active region between the gate and the drain electrode and between the gate and the source electrode. A field plate is on the spacer layer and extends on the spacer and over the active region toward the drain electrode. The field plate also extends on the spacer layer over the active region and toward the source electrode. At least one conductive path electrically connects the field plate to the source electrode or the gate.