SiC-GaN 3D Hall Sensor for High-Temperature Magnetic Field Monitoring
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Solution Overview
Problem
Conventional Hall sensors made from narrow band-gap semiconductor materials like silicon and gallium arsenide suffer from reduced carrier mobility and detection sensitivity at high temperatures, limiting their application to environments above 125°C, and existing three-dimensional Hall sensors are large, complex, and unable to perform real-time temperature monitoring.
Innovation Solution
A high-temperature three-dimensional Hall sensor is developed using a SiC substrate with epitaxially grown GaN heterojunctions, integrating vertical and horizontal Hall sensors to measure magnetic fields in any direction and monitor temperature in real-time, with a compact design and high sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional narrow band-gap semiconductor materials (Si, GaAs) are used to make Hall sensors, then the sensors can be manufactured with ease and low cost, but the detection sensitivity is seriously attenuated and the sensors cannot work normally in high-temperature environments above 125°C
Solution Approach 1:
The patent uses a heterojunction structure combining SiC substrate with GaN epitaxial layer. The SiC substrate provides high-temperature stability and mechanical support, while the GaN layer provides high electron mobility and sensitivity. This composite material approach enables the sensor to operate reliably above 400°C while maintaining manufacturing feasibility through established heteroepitaxial growth techniques.
Solution Approach 2:
The patent changes the material parameters by selecting wide band-gap materials (SiC with 3.25 eV band gap and GaN with 3.4 eV band gap) instead of narrow band-gap materials. This parameter change fundamentally improves the carrier mobility temperature dependence, allowing the sensor to maintain functionality at temperatures above 400°C where conventional materials fail.
2Adaptability or versatility
If three one-dimensional Hall sensors are integrated to form a three-dimensional Hall sensor, then magnetic field measurement in any direction is achieved, but the sensor size becomes large and wiring becomes complicated
Solution Approach 1:
The patent merges three one-dimensional Hall sensor elements into a single integrated three-dimensional Hall sensor structure on the GaN layer. The Hall elements are arranged in orthogonal orientations and share common electrical connections, enabling measurement of magnetic fields in X, Y, and Z directions simultaneously. This merging reduces the overall device footprint and simplifies wiring compared to using three separate sensors.
Solution Approach 2:
The patent transitions from planar two-dimensional sensor arrangements to a three-dimensional structure by utilizing vertical Hall elements that sense magnetic fields in the Z-direction perpendicular to the substrate surface. This dimensional extension allows true three-dimensional magnetic field sensing capability within a compact footprint, avoiding the need for large-area planar integration.
3Reliability
If GaN heterojunction-based Hall sensors are used for high-temperature working, then the sensors can operate above 125°C, but they can only measure one-dimensional longitudinal magnetic field and cannot monitor working temperature in real time
Solution Approach 1:
The patent integrates multiple functions into a single sensor device: (1) three-dimensional magnetic field sensing capability measuring Bx, By, and Bz components, (2) real-time temperature monitoring through integrated temperature-sensitive structures, and (3) high-temperature operation above 400°C. This multi-functional integration allows the sensor to simultaneously perform magnetic field measurement and environmental monitoring without requiring separate devices.
Solution Approach 2:
The patent segments the sensor into functionally distinct regions: Hall sensing elements for magnetic field detection, temperature-sensitive structures for thermal monitoring, and separate electrode configurations for different measurement modes. This segmentation allows each function to be optimized independently while maintaining compact integration, enabling both magnetic field sensing and temperature monitoring to coexist without interference.
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 sensor operates stably above 400°C, maintains high sensitivity, and allows for accurate magnetic field and temperature monitoring without affecting normal sensor operation, suitable for various applications including aerospace and medical devices.
Implementation Method 1
there is the high-density two-dimensional electron gas (2 DEG) induced by polarization charges in the potential well at the interface of GaN material heterojunctions
Implementation Method 2
Hall sensors based on the principle of the Hall effect are the important representative of magnetic sensors
Implementation Method 3
the SiC material has the wide band gap (about 3.25 eV) and high thermal conductivity (3 ̃5 W/(cm K))
Data Source
AI summary
A high-temperature three-dimensional Hall sensor with a real-time working temperature monitoring function includes a buffer layer, an epitaxial layer, and a barrier layer sequentially grown on a substrate. A high-density two-dimensional electron gas is induced by polarization charges in a potential well at an interface of heterojunctions of the epitaxial layer. A lower surface of the substrate includes a vertical Hall sensor for sensing a magnetic field parallel to a surface of a device. An upper surface of the barrier layer includes a “cross” horizontal Hall sensor for sensing a magnetic field perpendicular to the surface of the device.