SnO2 Films Deposited by Ultrasonic Spray Pyrolysis: Influence of Al Incorporation on the Properties

• Published in: Molecules (Basel, Switzerland) Switzerland), 2019-07, Vol.24 (15), p.2797
• Main Authors: Deyu, Getnet Kacha, Muñoz-Rojas, David, Rapenne, Laetitia, Deschanvres, Jean-Luc, Klein, Andreas, Jiménez, Carmen, Bellet, Daniel
• Format: Article
• Language: English
• Subjects: Aluminum; Chemical Sciences; Chemical vapor deposition; Doping; Electrical conductivity; Electrical properties; Electrical resistivity; Fluorine; Grain size; Lattice parameters; Material chemistry; Molecular beam epitaxy; Oxide coatings; Pyrolysis; Radiation; Scanning electron microscopy; Spectrum analysis; Spray pyrolysis; Thin films; Tin dioxide; tin oxide; Tin oxides; transparent conductive oxide
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules24152797

Aluminum-doped tin oxide (SnO 2 :Al) thin films were produced by an ultrasonic spray pyrolysis method. The effect of aluminum doping on structural, optical, and electrical properties of tin oxide thin films synthesized at 420 ° C was investigated. Al doping induced a change in the morphology of tin oxide films and yielded films with smaller grain size. SnO 2 thin films undergo a structural reordering and have a texture transition from (301) to (101), and then to (002) preferred cristallographic orientation upon Al doping. The lattice parameters (a and c) decreases with Al doping, following in a first approximation Vegard’s law. The optical transmission does not change in the visible region with an average transmittance value of 72–81%. Conversely, in the near infrared (NIR) region, the plasmon frequency shifts towards the IR region upon increasing Al concentration in the grown films. Nominally undoped SnO 2 have a conductivity of ∼1120 S/cm, which is at least two orders of magnitude larger than what is reported in literature. This higher conductivity is attributed to the Cl − ions in the SnCl 4 ·5(H 2 O) precursor, which would act as donor dopants. The introduction of Al into the SnO 2 lattice showed a decrease of the electrical conductivity of SnO 2 due to compensating hole generation. These findings will be useful for further studied tackling the tailoring of the properties of highly demanded fluorine doped tin oxide (FTO) films.