GaN Dual-Gate Transistor Short Channel Effect Control
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Solution Overview
Problem
Power semiconductor devices using silicon are reaching limits in breakdown voltage and on-resistance, and nitride semiconductor devices face challenges with short channel effects and threshold voltage controllability due to miniaturization of field effect transistors.
Innovation Solution
A nitride semiconductor device with a GaN-based semiconductor structure, featuring a first and second semiconductor layer, source and drain electrodes, and dual gate electrodes with a protrusion portion, allows for control of the threshold voltage by applying negative and positive voltages to the back gate and top gate respectively, effectively managing the short channel effect and improving breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the gate length is shortened for miniaturization, then the device size is reduced and switching speed is improved, but the short channel effect increases and threshold voltage controllability deteriorates
Solution Approach 1:
The gate structure is segmented into a top gate and a back gate, allowing independent control of threshold voltage and channel current. The back gate specifically addresses threshold voltage controllability while the top gate controls channel current, resolving the short channel effect issue without compromising miniaturization benefits.
Solution Approach 2:
The control mechanism is extended from one dimension (top gate only) to three dimensions by adding the back gate. This spatial extension allows the electric field to penetrate through the semiconductor layer from both top and bottom, providing enhanced threshold voltage control in miniaturized devices.
2Length of moving object
If the gate length is shortened for miniaturization, then the device size is reduced, but the on-resistance decreases due to increased short channel effect
Solution Approach 1:
By dividing the gate into top and back components, the device achieves better electrostatic control over the channel. The back gate's electric field penetrates the semiconductor layer to suppress carrier leakage and reduce short channel effects, thereby maintaining lower on-resistance in miniaturized structures.
3Device complexity
If a single gate structure is used, then the device complexity is low, but the threshold voltage controllability is insufficient for miniaturized devices
Solution Approach 1:
The gate is segmented into top and back gates with distinct functions: the back gate controls threshold voltage by modulating the potential at the AlGaN/GaN interface, while the top gate controls channel current. This segmentation provides enhanced controllability without excessive complexity.
Solution Approach 2:
The dual gate structure provides multi-functionality: the back gate handles threshold voltage adjustment and short channel effect suppression, while the top gate handles channel current control. This division of labor allows each gate to be optimized for its specific function, improving overall device performance.
Data Source
AI summary
A nitride semiconductor device includes a first semiconductor layer including a nitride semiconductor, a second semiconductor layer contacting the first semiconductor layer and including a nitride semiconductor, a source electrode, a drain electrode, a first gate electrode, a second gate electrode provided on an opposite side, a first insulating layer and a second insulating layer. The gate electrode has a protrusion portion inside the semiconductor layer. A distance between the first gate electrode and the protrusion portion of the second gate electrode is shorter than a distance between the source electrode and the second insulating layer, and shorter than a distance between the drain electrode and the second insulating layer.