Fabrication of Nb-doped ZnO nanowall structure by RF magnetron sputter for enhanced gas-sensing properties

• Published in: Journal of alloys and compounds 2017-03, Vol.698, p.77-86
• Main Authors: Kim, Seong-Hwan, Shim, Gyu-In, Choi, Se-Young
• Format: Article
• Language: English
• Subjects: Acetone; Alloys; Detection; Doping; Emission spectroscopy; Ethanol; Exposure; Field emission; Gas sensors; High resolution; Magnetic properties; Magnetron sputtering; Nanofabrications; Nanostructure; Nanostructured compounds; Nanostructured materials; Operating temperature; Point defects; Radio frequency; Scanning microscopy; Specific surface; Surface area; Surfaces and interfaces; Transition metal alloys and compounds; Transmission electron microscopy; X ray photoelectron spectroscopy; X-ray diffraction; Zinc oxide; Zinc oxides
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.11.377

An Nb-doped ZnO nanowall is fabricated by radio-frequency (RF) magnetron sputtering at 250 °C for application in a gas sensor. The fabricated Nb-doped ZnO nanowall is characterized by field emission scanning microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Nb-doped ZnO nanowall is observed to show a predominant exposed polarized (002) plane. The specific surface area is increased relative to that of the parent ZnO nanowall from 9.2 ± 0.42 m2 g−1 to 9.8 ± 0.52 m2 g−1. The segregation of Nb does not occur in the Nb-doped sample observed by TEM; this indicates that the addition of Nb occurs within the solid-solution limit of the ZnO host lattice. The Nb-doped ZnO nanowall gas sensor presents excellent gas sensing properties for acetone and ethanol gases at a relatively low operating temperature. We confirm the effects of Nb-doping on the ZnO nanowall, such as the exposed (002) plane, specific surface area increase, and electronic structural changes. Nb doping of the ZnO host lattice is a promising method that enhances the acetone and ethanol gas-sensing capacity at a relatively low operating temperature. [Display omitted] •Nb-doped ZnO nanowalls were grown by RF magnetron sputtering.•Nb doping increased crystallinity, surface area, & charge carrier concentration.•Doped ZnO showed good sensitivity (resistance changes) to reducing target gases.•Gas sensors of nanowalls showed lower operating temperatures than other sensors did.•Growth & sensing enhancement mechanisms were elucidated.