Ammonia Gas Sensing Using ZnO Nanowires Synthesized by Thermal Oxidation of Zn Film

Abstract

In this work, long, dense and uniformly distributed ZnO nanowires have been synthesized and studied as the sensing element for detection of ammonia gas. For this purpose, 130 nm thick Zn film was deposited on oxidized Si substrate by RF magnetron sputtering at the rate of 4.5 nm/min in Ar ambient. The film was thermally oxidized at 500 ⁰C in moist environment for 1 hr. The structural phase of post-oxidized sample indicated that Zn film was completely oxidized. The morphology indicated that Zn was covered into nanowires of ZnO. The diameter of nanowires was estimated to be about 40-50 nm and the length was in the range of few tens of micron. MEMS technology was used to integrate these nanowires to fabricate a gas sensing device. The device showed excellent sensing performance towards trace amount of ammonia gas.