Influence of Quenching on the Opto-Electronic Properties of F:SnO₂ Layers

For many opto-electronic applications, F:SnO₂ materials must benefit from high transparency, high conductivity, and high mechanical strength even after quenching. The purpose of this study was to investigate the influence of quenching on the opto-electronic properties of the F:SnO₂ layers synthesized at high temperature on Si C O-coated soda-lime glass by atmospheric chemical vapor deposition. The morphology, structure, and composition of the layers were studied before and after quenching in air- and oxygen-rich atmospheres at 670 °C. The free carrier concentration was reduced by oxygen vacancy (V_O) passivation, as well as by F and Na diffusion, with all effects scaling up with quenching time in air. The transmittance also decreased with quenching time as Na impurities acted as absorption and electron recombination centers. In an oxygen-rich atmosphere, the V_O passivation was even more emphasized, with however a moderate contribution to conductivity loss. The F:SnO₂ layer microstructure and composition were rather fringed through high-temperature deposition. The almost invariable free carrier concentration and transmittance of the F:SnO₂ samples quenched in O₂ versus air were related to a moderation in Na diffusion. For long quenching times (>20 min) in air, Na and F diffusion prevailed explaining the conductivity drop.