Key points of announcement
- New quantum manipulation improves the temperature sensitivity of silicon carbide (SiC) quantum sensors by more than 10 times
- Successful measurement in the high temperature range above 100°C, which was not possible with previous method
- Quantum technology useful for performance improvement and quality control of SiC power semiconductors
A research team led by Researcher Yuichi Yamazaki, Senior Director of Takasaki Advanced Radiation Research Institute, Quantum Materials and Applications Research Center (QUARC), National Institutes for Quantum Science and Technology (QST) (President Dr. Shigeo Koyasu) has achieved high sensitivity for temperature measurement using a silicon vacancy (VSi) in silicon carbide (SiC) promising for direct-investigation tool inside of SiC-based semiconductors. Measuring temperatures up to 120°C, which is much higher than the previously measured value of 50°C, has been succeeded.
QST has a technology to irradiate a precisely position-controlled ion beam into a SiC-based semiconductor, which is performed to form VSi (SiC-VSi) as known as a spin defect inside the semiconductor. Since SiC-VSi acts as a quantum sensor that can simultaneously measure magnetic-field and temperature, it is expected to be the unique technology that can directly observe the current (derived from magnetic-field) and temperature at the target location inside a SiC-based power semiconductor in operation. Detailed data measured by the SiC-VSi based quantum sensor will contribute to performance improvement such as durability and failure prediction which improves economic efficiency by understanding the appropriate replacement timing. However, the SiC-VSi quantum sensor has extremely low sensitivity to temperature compared to that to magnetic-field. It is difficult to measure temperature in the high temperature region above 50°C because of a small signal from the sensor. Therefore, sensor sensitivity to temperature should be improved for practical application.
Considering on the fact that the SiC-VSi quantum sensor is more sensitive to magnetic-field than temperature, the research team developed a new quantum manipulation to add a change indicating temperature to a signal indicating magnetic-field, instead of measuring temperature directly. A signal intensity required for temperature measurement was improved to be more than 10 times larger than that for the conventional method. Thus, temperature measurement over 120°C was demonstrated. Furthermore, it is expected to be possible to measure up to 175°C from the viewpoint of the signal intensity, where the temperature is a guaranteed operation one of commercially available SiC power semiconductors used in electric vehicles, etc. This result is an important step toward the practical application of SiC-VSi based quantum sensors.
With this result, SiC-VSi based quantum sensor, which can be directly embedded in a SiC power semiconductor, is possible to measure magnetic-field and temperature with an equivalent sensor sensitivity. This enables us to know an internal state of a SiC power semiconductor in operation with high time efficiency by simultaneous measurement of the local temperature and current.
This research was partially supported by Quantum Leap Flagship Program (Q-LEAP) “Creation of Innovative Sensor Systems by Advanced Control of Solid-State Quantum Sensors” (JPMXS 0118067395) and KAKENHI (21H04553, 20H00355). This research was published in Physical Review Applied on September 6, 2023.