Vertical GaN Heterojunction Transistor Structure for Leakage Reduction
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Solution Overview
Problem
Group III nitride transistors, particularly GaN HEMTs, face challenges with high reverse conduction voltage drops and increased power consumption due to the lack of a body diode, leading to high leakage currents and reliability issues, especially when integrated with Si-based Schottky diodes, which hinder the advantages of GaN materials.
Innovation Solution
A group III nitride transistor structure is developed with vertically integrated diodes and transistors, utilizing high resistance materials and insertion layers for electrical isolation between heterojunctions, allowing for direct growth and process compatibility, reducing leakage current and power consumption by integrating diodes and transistors in a vertical direction on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Schottky diode is integrated with GaN HEMT on Si substrate, then reverse conduction capability is improved, but leakage current increases and reliability deteriorates due to material limitations
Solution Approach 1:
The patent merges the Schottky diode and HEMT into a single integrated structure where the diode anode and HEMT source share the same AlGaN/GaN heterojunction. This integration allows the device to achieve both rectification and switching functions while utilizing the superior material properties of GaN throughout the structure, avoiding the reliability issues of Si-based diodes.
Solution Approach 2:
The patent employs AlGaN/GaN heterostructure materials to construct both the diode and HEMT components. The composite material system provides high electron mobility and breakdown field strength, enabling low leakage current in reverse bias while maintaining high reliability, overcoming the limitations of Si-based Schottky diodes.
2Adaptability or versatility
If a crossed structure of HEMT and SBD is used, then reverse conduction capability is improved, but occupied area increases
Solution Approach 1:
The patent transitions from a planar crossed structure to a vertical stacked structure where the diode and HEMT are arranged in the vertical direction sharing common layers. This dimensional change allows both functions to be integrated in a compact footprint, significantly reducing the occupied area compared to lateral integration approaches.
3Adaptability or versatility
If transversely integrated SBD is used, then reverse conduction capability is improved, but leakage current increases
Solution Approach 1:
The patent inverts the conventional transverse integration approach by implementing vertical integration where the diode and HEMT share the vertical stack. This inversion allows the depletion region to extend vertically through the shared heterojunction, providing better leakage control while maintaining reverse conduction capability.
4Area of stationary object
If vertically integrated SBD is used, then occupied area is reduced, but leakage current control becomes difficult
Solution Approach 1:
The patent applies local quality by creating a shared AlGaN/GaN heterojunction region that serves dual functions: as the diode anode and as the HEMT source. This localized shared structure provides inherent leakage control through the heterojunction properties while maintaining compact vertical integration, resolving the control difficulty issue.
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 effectively minimizes the wafer area occupied, reduces leakage current and power consumption, enhances reliability and stability, and simplifies the fabrication process, while maintaining the advantages of GaN materials by using a mixed anode diode structure compatible with the HEMT process.
Implementation Method 1
the first heterojunction is electrically isolated from the second heterojunction via a high resistance material and/or insertion layer
Implementation Method 2
the third semiconductor can exhaust a part of the first two-dimensional electron gas located below the third semiconductor, and the sixth semiconductor can exhaust a part of the second two-dimensional electron gas located below the sixth semiconductor
Data Source
AI summary
A group III nitride transistor structure capable of reducing a leakage current and a fabricating method thereof are provided. The group III nitride transistor structure includes: a first heterojunction and a second heterojunction which are laminated, wherein the first heterojunction is electrically isolated from the second heterojunction via a high resistance material and/or insertion layer; a first electrode, a second electrode and a first gate which are matched with the first heterojunction, wherein a third semiconductor is arranged between the first gate and the first heterojunction, and the first gate is also electrically connected with the first electrode; a source, a drain and a second gate which are matched with the second heterojunction, wherein the source and the drain are also respectively electrically connected with the first gate and the second electrode, and a sixth semiconductor is arranged between the second gate and the second heterojunction.