Atomic scale faceting and its effect on the grain size distribution of SnO2 thin films during deposition

Abnormal grain growth (AGG) occurs when SnO2 thin films are deposited by conventional thermal CVD at 475 °C, and high-resolution transmission electron microscopy shows some of the interfaces to be atomically faceted. However, when deposited at 525 °C normal grain growth (NGG) occurs with all the interfaces smoothly curved and atomically rough. This correlation between interface structure and grain growth behavior is consistent with that observed previously in bulk materials. For the application of SnO2 thin films in sensors and transparent electrodes, 525 °C, which is just above the faceting transition temperature, was found to be the optimum deposition temperature due to its small grain size and high surface to volume ratio.