GaN Power Transistor pGaN Gate Interlayer for Threshold Stability
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Solution Overview
Problem
Gallium Nitride (GaN) power transistors with Schottky pGaN gate modules face issues of threshold voltage instability and weakness in gate reliability, particularly due to high electric field peaks at the metal/pGaN interface and in the pGaN bulk, which affect dynamic instabilities and overall device performance.
Innovation Solution
A stable pGaN Schottky Gate with Interlayer structure is introduced, where a dedicated III-V interlayer is inserted between the pGaN layer and the metal gate, optimizing the gate module's performance by reducing electric field strength and enhancing threshold voltage stability and reliability through proper choice of interlayer thickness and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Schottky interface is used between metal gate and pGaN layer, then DC gate current is reduced, but threshold voltage stability deteriorates and gate reliability weakens
Solution Approach 1:
An AlGaN interlayer is introduced between the metal gate and the pGaN layer to act as an intermediary. This interlayer has intermediate properties: it forms a Schottky junction with the metal gate to reduce DC current, while its wider bandgap and proper thickness prevent excessive electric field penetration into the pGaN bulk, thereby maintaining threshold voltage stability and improving gate reliability.
Solution Approach 2:
The bandgap parameter is changed by introducing AlGaN material with a wider bandgap than pure GaN. By controlling the Al composition ratio and layer thickness, the electric field distribution is optimized to reduce peak fields at critical interfaces while maintaining the Schottky barrier functionality for DC current reduction.
2Use of energy by moving object
If a Schottky interface is used between metal gate and pGaN layer, then DC gate current is reduced, but threshold voltage stability deteriorates
Solution Approach 1:
The AlGaN interlayer serves as a mediator that decouples the Schottky junction formation from the pGaN layer. It allows the metal gate to form a Schottky contact for DC current reduction while preventing the high electric field from directly affecting the pGaN threshold voltage, thus maintaining stability.
Solution Approach 2:
By changing the material composition to AlGaN with controlled aluminum content and optimizing the layer thickness parameter, the electric field distribution is modified to reduce peak fields at the metal/pGaN interface, thereby stabilizing the threshold voltage while maintaining low DC gate current.
3Device complexity
If metal gate directly contacts pGaN layer, then device structure is simple, but peak electric field strength increases causing dynamic instabilities
Solution Approach 1:
The AlGaN interlayer is positioned as a mediator between the metal gate and pGaN layer. Its wider bandgap material property causes the electric field to be distributed more favorably, reducing the peak field strength at the metal/pGaN interface and in the pGaN bulk, thereby eliminating dynamic instabilities while adding only one additional layer to the structure.
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 significantly improves threshold voltage stability and gate reliability by reducing peak electric field strength at the metal/pGaN interface and in the pGaN bulk, addressing the limitations of conventional Schottky gate approaches and enabling reliable operation of GaN power transistors.
Implementation Method 1
reducing peak electric field strength at the metal/pGaN interface and in the pGaN bulk
Implementation Method 2
metal gate layer is configured to electrically connect the p-type doped Gallium Nitride layer via the interlayer to form a rectifying metal-semiconductor junction
Data Source
AI summary
The disclosure relates to a Gallium Nitride power transistor, comprising: a buffer layer; and a barrier layer having a top side, a bottom side, the bottom side facing the buffer layer, the bottom side of the barrier layer is placed on the buffer layer; an interlayer interposed between a p-type doped Gallium Nitride layer and a metal gate layer, the interlayer is made of a III-V compound semiconductor comprising a combination of at least one group III element with at least one group V element, the p-type doped Gallium Nitride layer is placed on the top side of the barrier layer, the metal gate layer is electrically connected to the p-type doped Gallium Nitride layer via the interlayer to form a rectifying metal-semiconductor junction with the p-type doped Gallium Nitride layer.