Low-intensity ultraviolet light detector using a surface acoustic wave oscillator based on ZnO/LiNbO3 bilayer structure

Abstract

A surface acoustic wave (SAW) based ultraviolet (UV) light detector configured in the form of a SAW oscillator is investigated. The SAW oscillator consists of a ZnO/LiNbO3 bilayer structure, where ZnO is used as UV light sensing material and LiNbO3 is used to excite the surface acoustic waves. The SAW oscillator is characterized for its functional performance at different Vcc, the voltage to the oscillator circuit, under different levels of UV light illumination. The changes in the amplitude and the frequency shift of the SAW oscillator output exhibit a linear variation with UV light intensity. The SAW UV detector is shown to be highly sensitive at lower Vcc. A low level UV intensity of 450 nW cm−2 is easily detectable and the voltage responsivity is estimated to be ∼24 kV W−1.