Two-dimensional recrystallisation processes of nanometric vanadium oxide thin films grown by atomic layer chemical vapor deposition (ALCVD) evidenced by AFM

The influence of thermal annealing on the morphology and structure of nanometer range thickness vanadium oxide films deposited by ALCVD on silicon substrate was investigated by AFM. The appearance of crystalline centres with typical rectangular V 2O 5 plates was clearly observed from 400 °C. Furthermore, spectacular 2D-reorganisation phenomenon with increasing temperature was pointed out since, initial circular particles change to elongated ones with a rectangular shape with increasing temperature. This reorganisation process results from an increase in the high surface atomic mobilities with increasing temperature. The growth of V 2O 5 particles in the ab-plane occurs preferentially along the b-direction for which the atoms density is higher, in good agreement with results previously deduced from XRD analyses. The latter show limitation of the coherence domains values along the a-axis for temperatures higher than 450 °C.