A new technique for growing large surface area SnO₂thin film (RGTO technique)

Abstract

A new technique for growing SnO, thin films with high surface area is described, based on tin rheotaxial growth and its thermal oxidation (RGTO). Tin thin films, when grown, present a surface characterized by spheroidal agglomerates due essentially to the surface tension of the liquid metal; these agglomerates do not seem to have any electrical continuity. By means of a thermal oxidation, both the transformation of the metal into a semiconductor and the thin film continuity are obtained, owing to the volume increase during the above-mentioned phase transformation. After this annealing cycle, SnO, thin films are slightly oriented in the (101) direction and present an electrical resistivity equal to about 10' R cm. So, the surfaces of SnO, films appear to be formed by spongeous agglomerates, which are in electrical contact with the nearest agglomerates. SnO, thin films grown by this method show a high sensitivity (defined as the relative per cent conductance variation) to H, ; in fact, sensitivity to 200 PPM H, in synthetic air at ambient pressure is equal to 400 YO. It seems to be possible to prepare other metal oxide semiconducting thin films with a high surface area using this technique.

Environmental monitoring system compliant with the IEEE 1451 standard and featuring a simplified transducer interface

“…On top of these hotplates, the gas sensing material (tin oxide, SnO 2 ) is deposited by means of a deposition technique developed and optimized at CNR IMM-Bologna consisting of a modified version of the rheotaxial growth and thermal oxidation (RGTO) technique [24]. This optimization concerned the tuning of the typical sputtering deposition parameters (RF power, deposition times, substrate temperature, etc.)…”

Monitoring plants health in greenhouse for space missions

“…Different oxides were used like SnO 2 doped with Ag, Au and Mo, mixed Sn and In oxide and WO 3 : details on their preparation are described elsewhere [10,11]. Preliminary functional characterization was carried out in the laboratory by a volt-amperometric technique.…”

Structural characterization of V2O5–TiO2 thin films deposited by RF sputtering from a titanium target with vanadium insets

“…Thus, the possibility to exploit these features for the production of sensors for some interesting gases like ethanol or carbon monoxide has been investigated in last years. Radio frequency (RF)-magnetron sputtering is one of the most suitable techniques for the industrial scaling-up of the thin films deposition process, and important progresses for the synthesis of high-quality thin films onto large areas substrates have been obtained by means of the Rheotaxial technique (RGTO) [4]. Recently, a novel technique based on the film deposition starting from a target addicted with a controlled amount of dopant insets has been developed [5].…”