Investigation of Rapid Gas-Sensitive Properties Degradation of ZnO–SnO2 Thin Films Grown on the Glass Substrate

Abstract

ZnO–SnO2 films with a thickness of up to 120 nm have been prepared on glass substrates by pyrolysis at 550 °C of three spin-coated organic precursors films. Films of four compositions were obtained on glass substrates. The prepared films were characterized by SEM, XRD, and XPS analysis. Electrophysical studies have shown that the activation energy of the temperature conductivity for all films is equal to 0.75 eV. While the gas-sensitive characteristics by CO treatment in low concentrations at a temperature of 200–300 °C was studied, their rapid degradation was found. Studies using the XPS method have shown that ZnO–SnO2 films contain sodium, which is diffused from the soda-lime glass substrate during the film formation. Studies of XPS spectra after CO treatment have shown that the film surface is almost 50% composed of adsorbed water molecules and OH groups. OH groups are part of the sodium, tin, and zinc hydroxides formed on the surface. In addition, zinc hydrocarbonates are formed on the surface of the films. The detected insoluble compounds lead to the degradation of gas-sensitive properties of ZnO–SnO2 films.

High Gas Sensitivity to Nitrogen Dioxide of Nanocomposite ZnO-SnO2 Films Activated by a Surface Electric Field

“…The choice of gas-sensitive materials is determined by the following requirement: "simple technology-high-quality, reproducible and fast response to a given concentration." The solid-phase pyrolysis method proposed in this work and in our other works [15,36] satisfies this requirement. Using the described method, it is possible to obtain composite nanoscale materials of various compositions with high values of gas-sensitive characteristics.…”

“…Each layer was dried in air and in a drying cabinet at a temperature of 100 • C. Heat treatment was carried out at 500 • C for two hours (Figure 1). The synthesis technique is described in more detail in previous studies [15,36]. To make gas sensors based on ZnO-SnO2 thin films, precursor was applied over a Pt counter-pin structure multi-sensor platform, MSP 632, and dried at 100 °C.…”

“…Nanocomposite materials based on SnO 2 are obtained by various methods [22], such as magnetron sputtering methods [25], chemical technologies [26][27][28], atomic layer deposition [29], the microwave hydrothermal method [30,31], magnetron sputtering [32], spray [33][34][35] or solid-phase [36,37] pyrolysis, etc. During the preparation of this article, the authors analyzed the available publications devoted to the study of the gas-sensitive and physicochemical properties of composite materials based on SnO 2 with a small concentration of ZnO.…”

Polycrystalline Transparent Al-Doped ZnO Thin Films for Photosensitivity and Optoelectronic Applications

“…The kinetics of the obtained films photoconductivity was studied using equipment [ 38 , 43 ] which allows the measurement of the photoresponse of the studied film by radiation from LED with a wavelength of 400 nm (GNL type, Ningbo, Zhejiang, China). The photoconductivity was controlled by a digital multimeter (Tektronix DMM4050, Keithley Instruments, Cleveland, OH, USA).…”

“…One of the simple, inexpensive and promising films synthesis methods is solid-phase pyrolysis, which allows the obtention of films of various compositions: ZnO-SnO 2 [ 35 , 36 , 37 ], Co 3 O 4 -ZnO [ 38 ]. By this method, using heat treatment at 600 °C, transparent ZnO films containing 1 and 3% Al 3+ were obtained [ 39 ]; they had a transmittance of more than 90%.…”