GaN Gate Structure With Voltage Limiting and Charge Bleed-Off
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Solution Overview
Problem
Conventional gallium nitride power devices with p-GaN cap layers suffer from small gate voltage swing and unstable thresholds, leading to complex circuit design, reliability issues, and instability under high gate voltages.
Innovation Solution
A gallium nitride power device with a novel structure comprising voltage-limiting, power, and bleed-off tube regions, utilizing P-type gallium nitride cap layers and PFET gate dielectric layers to enhance gate voltage swing and threshold stability, with isolation regions for reduced parasitism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional Schottky gate structure with p-GaN cap layer is used, then the device can operate in enhancement mode, but the gate voltage swing range is limited to not more than 8 V
Solution Approach 1:
The device is divided into three distinct tube regions (voltage-limiting, power, and bleed-off) with different gate structures. The voltage-limiting tube region uses a Schottky gate to clamp the gate voltage of the power tube region, enabling the power tube region to achieve larger voltage swing (up to 20V) without directly requiring the full voltage range at its gate, thus reducing circuit design complexity while expanding operational range.
2Reliability
If a conventional Schottky gate structure with p-GaN cap layer is used, then the device can be fabricated with current epitaxial techniques, but the threshold voltage becomes unstable under repeated switching due to charge storage effect
Solution Approach 1:
The bleed-off tube region is specifically designed to extract and remove stored charges from the p-GaN cap layer of the power tube region through its reverse-biased diode structure. This separate charge removal function stabilizes the threshold voltage by preventing charge accumulation that would otherwise cause instability under repeated switching, while still using standard epitaxial fabrication techniques.
3Ease of operation
If an ohmic gate structure with p-GaN cap layer is used, then the device can operate at high gate voltages, but the gate leakage increases and gate voltage swing decreases
Solution Approach 1:
The gate structure is made dynamic through the voltage-limiting tube region's Schottky gate, which actively clamps the gate voltage of the power tube region during operation. This dynamic voltage clamping prevents the gate voltage from exceeding safe levels (reducing gate leakage) while still allowing the drain-source voltage to achieve high swing ranges, effectively adapting the gate voltage behavior to operational 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
The device achieves increased gate voltage swing, enhanced threshold stability, and improved integration with reduced parasitic effects, enabling stable operation across a wide range of gate voltages.
Implementation Method 1
a two-dimensional electron gas (2DEG) with high mobility and high electron saturation rate can be produced on the surface region of GaN without doping due to the action of spontaneous polarization and piezoelectric polarization within the structure
Implementation Method 2
a two-dimensional electron gas (2DEG) with high mobility and high electron saturation rate can be produced on the surface region of GaN without doping due to the action of spontaneous polarization and piezoelectric polarization within the structure
Data Source
AI summary
A gallium nitride power device with wide-range working gate voltage structurally includes a base and isolation regions, wherein the base is provided with a substrate, a nucleating layer, a buffer layer, a channel layer, a barrier layer and a passivation layer in sequence from the bottom up, and a voltage-limiting tube region, a power tube region and a bleed-off tube region are arranged on the barrier layer. A first metallic drain electrode in the voltage-limiting tube region and a third metallic gate electrode in the bleed-off tube region are connected via a first metallic interconnector and connected to an input gate voltage, and a first metallic source electrode in the voltage-limiting tube region, a second metallic gate electrode in the power tube region and a third metallic drain electrode in the bleed-off tube region are connected via a second metallic interconnector,