Qualitative and quantitative analysis of surface-acoustic-wave-based ultraviolet photodetectors

Surface-acoustic-wave (SAW) based ultraviolet (UV) photodetectors with multiple optical sensing areas is presented by depositing patterned ZnO films on a LiNbO3 substrate. Two different types of electrodes, uniform interdigital transducer (IDT) and slanted finger interdigital transducer (SFIT), are designed and fabricated to analyze the performances of SAW array UV photodetectors. By tuning ultraviolet wavelengths, qualitative characteristics of SAW UV photodetectors are observed through the measurements of SAW attenuation. Quantitative analyses of the photodetectors are presented by varying light intensities. Moreover, dynamic responses of SAW array UV photodetectors under the illumination of different optical wavelengths are also demonstrated. Ultraviolet light of 350 nm with power densities of 8.46 and 18.34 μW/cm2 is detectable from a UV photodetector with uniform IDT and SFIT, respectively. This study not only indicates that a SAW-based UV sensor is a potential candidate of array UV photodetectors but also provides a comprehensive analysis of SAW UV photodetectors.