Development of HfO₂-Based Solar-Blind SAW UV-C Sensor for Corona Discharge Detection Application
This study presents a novel surface acoustic wave (SAW)-based solar-blind ultraviolet-C (UV-C) corona sensor, marking the first reported use of HfO₂ as a sensing material for UV-C corona sensing. A 222 MHz two-port SAW delay line structure was selected as a sensor platform, and its optimal parameter...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Applied Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-3417/15/1/464 |
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| Summary: | This study presents a novel surface acoustic wave (SAW)-based solar-blind ultraviolet-C (UV-C) corona sensor, marking the first reported use of HfO₂ as a sensing material for UV-C corona sensing. A 222 MHz two-port SAW delay line structure was selected as a sensor platform, and its optimal parameters were determined through Coupling of Mode (COM) modeling analysis. COMSOL simulations were conducted to investigate the effect of UV-C exposure on the HfO<sub>2</sub> thin film, highlighting its contribution to conductivity changes. A 30 nm-thick HfO<sub>2</sub> thin film was deposited using atomic layer deposition (ALD) within the cavity of a two-port SAW delay line, providing sufficient volume and density of absorption sites for UV-C exposure. Comprehensive material characterization of the HfO<sub>2</sub> thin film was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The effect of annealing temperature was analyzed in detail, with results confirming that 500 °C is the optimal temperature for achieving the best performance in a SAW-based UV-C corona sensor. The sensor characteristics were measured using custom-made interface electronics, allowing frequency shifts to be visually observed on a PC monitor with compensation for environmental factors such as humidity and temperature. The developed sensor demonstrated response and recovery times of 2.8 s and 4 s, respectively, with a measured sensitivity of 563 ppm/(mW·cm<sup>−2</sup>). Furthermore, the effect of HfO₂ film thickness on the sensor’s response to UV-C exposure was examined in detail, showing that increased thickness leads to a higher frequency shift, thereby enhancing sensitivity. The feasibility of the sensor for real-world applications was validated through successful testing under simulated corona discharge detection. |
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| ISSN: | 2076-3417 |