UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Zinc oxide (ZnO) thin films are crucial for optoelectronic devices.
• Surface Acoustic Wave (SAW) devices offer sensitive detection capabilities.
• UV sensors are needed for various environmental and industrial applications.

Purpose of the Study:

• To fabricate and characterize ZnO thin films for UV sensing applications.
• To investigate the performance of ZnO-based SAW delay lines as UV sensors.
• To evaluate the sensor's response, reversibility, repeatability, and suitability for harsh environments.

Main Methods:

• Radio frequency sputtering for ZnO thin film deposition on fused silica.
• X-ray diffraction and scanning electron microscopy for material characterization.
• Fabrication of Al interdigitated transducers (IDTs) for SAW device.
• Testing UV response under varying illumination conditions and power densities.

Main Results:

• ZnO films exhibited hexagonal wurtzite structure, c-axis orientation, and dense columnar morphology.
• SAW sensor showed a measurable velocity shift due to UV light-induced acoustoelectric interaction.
• Achieved rise time of ~10s, recovery time of ~13s, and sensitivity up to 341 ppm/(mW/cm²).
• Demonstrated reversibility, repeatability, and potential for wireless interrogation.

Conclusions:

• ZnO/fused silica-based SAW devices are effective UV sensors.
• The backlighting interrogation method enhances suitability for harsh environments.
• These sensors offer a promising solution for UV detection in challenging conditions due to their robustness and wireless capabilities.