Synthesis and structural characterization of rutile SnO₂ nanocrystals

Abstract

Nanocrystalline tin dioxide (SnO 2 ) thin films were prepared on glass substrate by pulse laser deposition for the first time. The thin films were characterized for their composition, morphology, and crystalline structure by x-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. It was found that the thin films consisted only of the tetragonal phase SnO 2 with no structural change, and they were well crystallized during deposition. In most cases, SnO 2 particles were overlapped, predominantly grown on preferred (101) plane, and connected with two or three neighbors through necks. The average grain size of the as-prepared thin films was about 12 nm. These facts are of great importance for sensor characteristics, since smaller grains and preferred orientation properties provide higher gas sensitivity to the whole thin films. Our findings indicate that the n-type wide-band-gas semiconductor nanocrystalline thin films can be manipulated by using pulse laser deposition techniques, offering new opportunities to control material fabrication.

Microstructural evolution of oxides and semiconductor thin films

“…18. This is particularly intriguing when one notices that (1 1 0) and (1 0 1) planes are identified in the HRTEM image in our previous work [32]. In fact, the (1 1 0) and (1 0 1) diffraction rings are always clearly visible on SAED patterns of SnO 2 thin films regardless of their deposition method, either PLD or sputtering.…”

“…HRTEM observations showed that each crystallite was small, isolated, and dispersed in amorphous SnO 2 matrix. However, it can be seen that a few crystallites were connected with two or three neighbors through necks [31,32].…”

“…The nanocrystalline SnO 2 thin films have been shown to exhibit better gas-sensing performance than their micro-and/ or macrostructured counterparts [95]. Therefore, the investigation of the micro-and nanostructure characteristics of SnO 2 thin films, by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) [32,96], is an essential step towards a better understanding of how the growth conditions influence the thin film nanostructure which, in turn, determines the gassensing performance. In this context, the pulsed laser deposition (PLD) technique stands out by its unique features, such as its extremely high instantaneous deposition rate and the highly energetic ablated species that permit the growth of nanostructured thin films which exhibit unprecedented properties [53].…”

“…Under normal conditions it exists in the form of a crystalline phase known as cassiterite. Cassiterite has a rutile tetragonal crystal structure and its optical, electrical and gas-sensing properties have been extensively studied [32,54,163,[166][167][168][169]. Another form of SnO 2 with an orthorhombic structure is known to be stable only at high pressures and high temperatures.…”

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“…The crystallite size of nanoparticles changes its properties when compared to bulk particles. SnO 2 nanoparticles can be prepared by various synthesis routes like spray pyrolysis, coprecipitation, pulse laser deposition, sol-gel, hydrothermal, chemical vapour deposition, etc [10][11][12][13][14][15]. The controlled synthesis of SnO 2 nanoparticles have been possible using chemical co-precipitation method.…”