Pulsed laser deposition and characterization of textured Pd-doped-SnO2 thin films for gas sensing applications

Pd-doped-SnO2 thin films were grown on Si (100) substrates using pulsed laser deposition at room temperature. Scanning electron microscopy and atomic force microscopy studies showed that the film morphologies are strongly related to two major parameters: first, high O2 background pressure, namely ≥ 10 Pa, induces the formation of nanoparticles by condensation in the gas phase; second, when the target-substrate distance d t-s is close to the plume length L p, considering an adiabatic expansion, textured thin films are obtained. Their morphologies depend therefore on the O2 pressure, since by increasing the pressure from 10 to 100 Pa the film morphology changes from a cracked structure to a well developed cauliflower-like-structure with a columnar growth. X-ray photoelectron spectroscopy, energy dispersive X-ray and grazing incidence X-ray diffraction were also employed to analyze, respectively, the chemical bonding state, the chemical composition and the structure in the deposited films. Sub-stoichiometric thin films are also synthesized with a Pd content of about 2.3 at.% under O2 background pressures higher than 10 Pa