Vertical Gate III-Nitride Structure for Stable Threshold and Breakdown
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Solution Overview
Problem
Current III-Nitride (III-N) semiconductor devices, such as transistors and switches, face challenges in achieving stable threshold-voltage, low leakage current, and high breakdown voltages while maintaining low on-resistance, especially in high-voltage applications.
Innovation Solution
The development of lateral III-N devices with a vertical gate module, where the III-N material is oriented in either N-polar or group-III polar orientation, incorporating a p-type III-N body layer and an n-type III-N capping layer to modulate the channel conductivity and reduce high electric field effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lateral III-N device structure is used, then the device can be fabricated with standard processes, but the device exhibits unstable threshold-voltage, high leakage current, and low breakdown voltage
Solution Approach 1:
The patent introduces a vertical gate module that extends in the vertical dimension rather than purely lateral, creating a three-dimensional gate structure. This vertical component modulates the channel conductivity more effectively while reducing high electric field effects at the drain, thereby achieving stable threshold-voltage and high breakdown voltage without excessive structural complexity
Solution Approach 2:
The device employs composite material structures including p-type III-N body layer, n-type III-N capping layer, and AlGaN barrier layer with GaN channel layer. These composite layers work together to modulate channel conductivity, reduce leakage current, and enhance breakdown voltage through their complementary electrical and structural properties
2Loss of energy
If the gate and drain are positioned close together to reduce on-resistance, then the on-resistance decreases, but high electric field effects increase causing threshold-voltage instability and leakage
Solution Approach 1:
The vertical gate module extends vertically into the channel region, providing electrostatic control in the vertical dimension. This allows the gate to effectively modulate the channel conductivity even when the lateral distance between gate and drain is small, thereby maintaining low on-resistance while reducing the harmful high electric field effects that cause threshold-voltage instability
Solution Approach 2:
The p-type III-N body layer acts as an intermediary between the gate and the channel, and between the channel and the drain. This body layer modulates the electric field distribution, reducing the peak electric field at the drain while maintaining effective gate control, thereby enabling close gate-drain spacing without excessive high electric field effects
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 approach enables III-N devices to operate with stable threshold-voltages, low leakage current, and high breakdown voltages, while maintaining low on-resistance, thus improving the performance and reliability of III-N semiconductor devices.
Implementation Method 1
incorporating a p-type III-N body layer and an n-type III-N capping layer to modulate the channel conductivity
Implementation Method 2
a compositional difference between the III-N barrier layer and the III-N channel layer causes a 2DEG channel to be induced in the III-N channel layer
Data Source
AI summary
A lateral III-N device has a vertical gate module with III-N material orientated in an N-polar or a group-III polar orientation. A III-N material structure has a III-N buffer layer, a III-N barrier layer, and a III-N channel layer. A compositional difference between the III-N barrier layer and the III-N channel layer causes a 2DEG channel to be induced in the III-N channel layer. A p-type III-N body layer is disposed over the III-N channel layer in a source side access region but not over a drain side access region. A n-type III-N capping layer over the p-type III-N body layer. A source electrode that contacts the n-type III-N capping layer is electrically connected to the p-type III-N body layer and is electrically isolated from the 2DEG channel when the gate electrode is biased relative to the source electrode at a voltage that is below a threshold voltage.