Pt surface modification of SnO2 nanorod arrays for CO and H2 sensors

Abstract

Uniform SnO₂ nanorod arrays were deposited on a 4 inch SiO₂/Si wafer by plasma-enhanced chemical vapor deposition (PEVCD) at low deposition temperature of around 300 °C. The SnO₂ nanorods were connected at the roots, thus the nanorod sensors could be fabricated by a feasible way compatible with microelectronic processes. The surface of the sensors was modified by Pt nanoparticles deposited by dip coating and sputtering, respectively. The sensing properties of the Pt-modified SnO₂ nanorod sensors to CO and H₂ gases were comparatively studied. After surface modification of Pt, the sensing response to CO and H₂ gases increased dramatically. The 2 nm Pt-modified SnO₂ nanorod sensors by sputtering showed the best sensing performance. By increasing Pt thickness from 2 nm up to 20 nm, the optimal working temperature decreased by 30 °C while the sensing response also decreased by about 4 times. Comparing these two Pt modification approaches by dip coating and sputtering, both could achieve comparable promotion effect if the Pt thickness can be controlled around its optimal value. The deposition technique of SnO₂ nanorod arrays by PECVD has good potential for scale-up and the fabrication process of nanorod sensors possesses simplicity and good compatibility with contemporary microelectronics-based technology.