A ZnO nanorod-based SAW oscillator system for ultraviolet detection.

A high-precision ultraviolet (UV) detector combining ZnO nanostructure and a dual delay line surface acoustic wave (SAW) oscillator system is presented. The UV detector is made of ZnO nanorods on a 128 degrees YX-LiNbO(3)-based two-port SAW oscillator. The ZnO nanorod synthesized by chemical solution method is used as a UV sensing material. The center frequency of the SAW device is at 145 MHz. A dual delay line SAW oscillator system was constructed to eliminate external environmental fluctuations. Under illumination of a UV source consisting of an Xe lamp and a monochromator, frequency shifts of the UV detector were measured. A maximum frequency shift of over 40 kHz was observed under 365 nm illumination for several on-off cycles, indicating the ZnO nanorod-based detector was sensitive to UV light and with good repeatability. Moreover, frequency shifts reached a value of 19 kHz after 365 nm was turned on for 10 s, which implies a real-time high-sensitivity UV sensor was successfully fabricated. Results show a ZnO nanostructure-based SAW oscillator system is a promising candidate for a real-time, fast-response, high-precision UV detector.