SnO2 thin films prepared by ion beam induced CVD. Preparation and characterization

Tin dioxide thin films have been prepared by Ion Beam Induced Chemical Vapo ur Deposition [IBICVD]. The films, with a SnO2 stoichiometry as determined by XPS, are compact and homogeneous as revealed by SEM/TEM. Preparation was carried out on different substrates at 300 K [i.e. room temperature] or 67 3 K. Small differences were detected in the granular structure at these two different temperatures. In the two cases the films were partially crystall ine;and depicted the cassiterite structure of SnO2. Small crystallographic domains between 30 and 50 A and a preferential growth of certain planes are deduced from the analysis of the X-ray diagrams. The W-vis spectra are cha racterised by a oscillatory absorption behaviour typical of thin films depo sited on a transparent substrate with a different refraction index. The val ue of this optical parameter at lambda = 420 (+)(-) 20 for films with d gre ater than or equal to 2000 Angstrom was about 1.9, very close to the value of bulk SnO2. A selective deposition of the SnO2 films has been also intend ed by using a mask between the accelerated ion beam used by IBICVD and the substrate.