Neodymium Doping Effect On Nano-Films Of Tin Dioxide

Sn and SnO₂ thin films were prepared by vacuum deposition on glass and single-crystal Si[111] substrates to obtain the nano-films by heat-treatment in O₂ .Similarly, The nano- SnO₂ films Nd doped have been obtained by the same method. The effect of preparation , doping , substrate nature and annealing temperature on the structural, electronic, optical and sensitive parameters was studied with XRD, SEM, EDC and electrical measurements.The results showed that the Sn thin films can be grown on glass and single-crystal Si[111] substrates to obtain the nano-films by making use of analytical pure Sn powder as an evaporation source at 450 ℃ -750 ℃ of heat-treatment in large flux O₂. Similarly, the analytical pure SnO₂ powder can be used as an evaporation source under heat-treatment in large flux O₂ to obtain the SnO₂ thin films of high qualities. It was shown from the experiment that the Nd-doping reduces the resistance of films. The resistances of the thin films were 4.8 × 10⁴Ω/□ on glass substrate and 1.282 × 10³Ω/□ on silicon substrate respectively. The Nd-doping can restrain the growth of crystal grains of the thinfilms. An optimized structure appeared when Nd component was 5.0at%. Unfortunately, the optical transmission coefficient reduced about 50% at visible light region. The results also showed that the SnO2 films with Nd doped have best selectivity to butane. Meanwhile, the work temperature of the films can decrease to 280 °C . The different substrates can effect on the capability of thin films significantly. The thin films grown on the single crystal Si substrates had preferential growth tendency along [101], however, the preferential growth tendency disappeared after Nd doping and the thin films showed a kind of free growing states. At the same times, the thin films had a porous grain structure, and the average dimension of the crystal grains was about 50nm.