Chemical vapor deposition of tin oxide: Fundamentals and applications

Tin oxide thin layers have very beneficial properties such as a high transparency for visible light and electrical conductivity making these coatings suitable for a wide variety of applications, such as solar cells, and low-emissivity coatings for architectural glass windows. Each application requires different properties of the tin oxide layer. These properties can be tuned by adjusting the parameters of the chemical vapor deposition (CVD) process, the main technique used for applying the tin oxide layer to the substrate. This paper discusses the state of the art of the kinetic models for tin oxide CVD. In the case of organometallic precursors the gas-phase chemistry may be initiated by cleavage of the tin-carbon bond, followed by radical-driven chain reactions that enhance the overall decomposition rate. However, in commercial tin oxide CVD reactors the gas-phase temperature may be too low or the residence time too short for these reactions to occur, thereby favoring surface chemistry. Preliminary investigations of the MBTC-H2O-O-2 chemistry indicate that a mechanism comprising the reaction between gaseous oxygen and an adsorbed MBTC-H2O complex is a plausible model. (c) 2005 Elsevier B.V. All rights reserved.