The effect of annealing temperature on the statistical properties of WO 3 surface

We have studied the effect of annealing temperature on the statistical properties of WO 3 surface using atomic force microscopy (AFM) techniques. We have applied both level crossing and structure function methods. Level crossing analysis indicates an optimum annealing temperature of around 400 °C at which the effective area of the WO 3 thin film is maximum, whereas the composition of the surface remains stoichiometric. The complexity of the height fluctuation of surfaces was characterized by roughness, the roughness exponent and the lateral size of surface features. We have found that there is a phase transition at around 400 °C from one set to two sets of roughness parameters. This happens due to microstructural changes from amorphous to crystalline structure in the samples, which have already been found experimentally.