ANOMALOUS INCORPORATION OF FLUORINE IN TIN OXIDE-FILMS PRODUCED WITH THE PYROSOL METHOD

Using secondary ion mass spectrometry, we have studied the non-intentional (chlorine) and intentional (fluorine) doping of tin oxide produced by the pyrosol method. We found that both kinds of doping are dependent on the substrate temperature, but in rather different ways. The chlorine concentration decays exponentially with the substrate temperature, while the fluorine concentration presents a maximum around 350-degrees-C. We suggest that the higher stability of fluorine as dopant, when compared with chlorine, is responsible for this difference. We have performed a Monte Carlo simulation which supports this suggestion.