Air-Bridge Matrix Electrode for GaN HEMT Current Crowding
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Solution Overview
Problem
High electron mobility transistors (HEMTs) on Si substrates experience thermal effects due to current crowding when operated at high voltage conditions, affecting their performance and reliability.
Innovation Solution
The implementation of an air-bridge matrix (ABM) electrode structure, which includes a substrate with an epitaxial stack and a matrix electrode structure comprising first, second, and third electrodes, with bridges made of metal materials, enhances electrical and thermal conductivity, reducing drain-source on-resistance and improving current spreading by allowing two-dimensional current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If GaN HEMTs are operated at high voltage conditions, then power output is improved, but thermal effects due to current crowding worsen
Solution Approach 1:
The patent transitions from traditional planar electrode structures to a three-dimensional air-bridge matrix electrode structure. The bridges extend vertically above the epitaxial stack, creating multiple current flow paths in the vertical dimension. This dimensional change distributes current more evenly across the device area, reducing current crowding and associated thermal effects while maintaining high power output capability
Solution Approach 2:
The electrode structure is segmented into multiple discrete elements: first electrodes, second electrodes, and bridging elements arranged in a matrix pattern. This segmentation divides the current flow into multiple parallel paths through the epitaxial stack, preventing current concentration at single points and reducing thermal effects during high voltage operation
2Device complexity
If traditional electrode structures are used, then device simplicity is maintained, but current crowding and thermal effects worsen
Solution Approach 1:
The air-bridge matrix electrode structure introduces vertical bridging elements that extend above the epitaxial stack, creating three-dimensional current distribution. This dimensional enhancement improves reliability by distributing current flow and reducing thermal effects, while the modular matrix design maintains reasonable manufacturing complexity
Solution Approach 2:
The bridging elements act as intermediaries that electrically connect the first and second electrodes while extending into the space above the epitaxial stack. These intermediary structures provide additional current flow paths and improve heat dissipation, enhancing device reliability without requiring fundamental changes to the underlying GaN HEMT architecture
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 air-bridge matrix electrode structure effectively reduces current crowding and thermal effects, leading to improved current density, lower on-resistance, and increased breakdown voltage, while also enhancing heat dissipation and mechanical strength.
Implementation Method 1
The implementation of an air-bridge matrix (ABM) electrode structure, which includes a substrate with an epitaxial stack and a matrix electrode structure comprising first, second, and third electrodes, with bridges made of metal materials, enhances electrical and thermal conductivity
Implementation Method 2
The implementation of an air-bridge matrix (ABM) electrode structure, which includes a substrate with an epitaxial stack and a matrix electrode structure comprising first, second, and third electrodes, with bridges made of metal materials, enhances electrical and thermal conductivity
Data Source
AI summary
A high electron mobility transistor comprises a substrate, an epitaxial stack arranged above the substrate and having a first region and a second region surrounding the first region, a matrix electrode structure arranged in the first region. The matrix electrode comprises a plurality of first electrodes arranged on the epitaxial stack, a plurality of second electrodes arranged on the epitaxial stack and adjacent to the plurality of first electrodes, a plurality of third electrodes arranged adjacent to the plurality of first electrodes and second electrodes. One of the plurality of first electrodes comprises a first side, a second side, a third side and a fourth side. The first side and the third side are opposite sides, and the second side and the fourth side are opposite sides. Two of the plurality of second electrodes are arranged on the first side and the third side, and two of the plurality of third electrodes are arranged on the second side and the fourth side.