SnO 2 /multiwalled carbon nanotubes (MWNTs) have been studied as gas sensing materials. Compared with pure SnO 2 , SnO 2 /MWNTs exhibit improved ethanol sensing properties such as higher sensitivity and quicker response/recovery at 300°C. The sensitivity is 35, 65, 166 and 243 to 500, 1000, 2000 and 3000 ppm ethanol, respectively. The response time is about 1 s, and the recovery time is about 5 s. The sensing improvement is explained in terms of the appropriate basal resistance and enhanced signal transfer brought by MWNTs. metal oxide semiconductors, gas sensors, SnO 2 , multiwalled carbon nanotubes, ethanol Citation: Liu L, Zhuang J, Liu K X, et al. Improved and excellent ethanol sensing properties of SnO 2 /multiwalled carbon nanotubes.Metal oxide semiconductor-based gas sensors have attracted much focus owing to their tiny structure, low cost, and high compatibility with microelectronic processing [1]. Hitherto, the impressive and promising results regarding the synthesis, fabrication, chemical and physical properties of these metal oxide semiconductor sensing materials have been achieved [2][3][4]. The investigation of a good gas sensor is focused on the improvement of many requirements, including low basal resistance (resistance in air), high sensitivity, and quick response/recovery [5]. These properties are strongly dependent on the morphology and structure of materials, namely, grain size, surface area, dimension, as well as the type of grain network or porosity [6]. Thus extensive studies have been carried out on improving the sensing performance by adding catalysts, doping metals and metal oxides, decreasing grain size, controlling pore and surface defects, etc.[6].Recently, one-dimensional (1D) nanostructures have been proved to be promising sensing materials due to their high density of surface sites, increased surface-to-volume ratio (and hence are expected to be more sensitive), and the nanoscale size (likely to allow complete depletion from charge carriers) [7]. Researchers in the sensor field are nowadays oriented towards these kinds of nanostructures, in order to investigate the real capabilities of these novel 1D structures to improve the performance of bulk and thin/thick film chemical sensors [8]. Many 1D nanostructures such as ZnO nanobelts, TiO 2 nanofibers, SnO 2 nanorods, single-walled carbon nanotubes (SWNTs), and multiwalled carbon nanotubes (MWNTs) have been employed for sensing applications [8][9][10]. However, few papers on sensing performance of particle/1D nanostructure compounds have been explored. Additionally, the synthesis of high sensitive materials with quick response /recovery and low cost is still in great demand.Here, we report the ethanol sensing properties of SnO 2 /MWNTs. SnO 2 has been chosen in our experiment for its excellent sensing properties for the detection of both reducing and oxidizing gases [11,12]. On the other hand, MWNTs with high conductivity and large surface-to-volume

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et al. Influence of O 2 /Ar ratio on the properties of transparent conductive niobium-doped ZnO films.Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300℃. The influence of O 2 /Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10 −4 Ω·cm is obtained from the film deposited at the O 2 /Ar ratio of 1/12. The average optical transmittance of the films is over 90%.semiconductors, electrical properties, thin films, transparent conductive oxides, sputtering Transparent conductive oxide (TCO) thin films have been extensively studied for their practical applications, such as transparent electrodes, flat panel displays and solar cells [1] . Hitherto, different metal-oxide semiconductors such as In 2 O 3 , ZnO and SnO 2 have been employed to fabricate TCO thin films [2] . Among them, ZnO, a II-VI compound with hexagonal wurtzite crystal structure has attracted much focus owing to its distinctive optical, electronic and chemical properties [3][4][5][6][7][8] . Moreover, its low price and relatively low deposition temperature make it a good candidate for industrial applications. Several chemical and physical deposition techniques such as radio frequency (RF) sputtering, direct current (DC) sputtering, spray pyr7olysis, chemical-vapor deposition (CVD), pulsed laser ablation (PLA), sol-gel, reactive thermal evaporation and ion plating have been used to deposit ZnO TCO thin films [9] , and the film properties can be adjusted by controlling the doping materials and ratios [10] , deposition parameters [11] and post treatment [12] . Many scientific and technological efforts have been made in these fields, aiming at increasing the conductivity, transmission, stability and feasibility for practical use [13][14][15][16] . However, to the best of our knowledge, no report on the preparation of Nb-doped ZnO (NZO) thin films by RF sputtering has been explored [17] . On the other hand, as the TCO thin film properties strongly depend on the reaction between material source and oxygen [18] , exposing the dependence of film properties on O 2 /Ar ratio is useful in the future science.In the present work, highly transparent and conductive NZO thin films are deposited on glass substrates by RF sputtering at 300℃ with different O 2 /Ar ratios. The influence of O 2 /Ar ratio on the structural, electrical and optical properties of the NZO films is investigated and discussed.