Morphology characterization and friction coefficient determination of sputtered V2O5 films

The morphology of V2O5 low-friction coatings on MgO (001) substrates synthesized by unbalanced reactive magnetron sputtering was investigated using atomic force microscopy. Analyzing the height–height correlation function, the evolution of the surface roughness parameters root mean square roughness (rms), lateral correlation length, and the Hurst parameter were determined. Studying samples of V2O5 grown at temperatures from 25 °C to 300 °C, a transition from amorphous to crystalline growth at 80 °C was observed. The rms roughness increased from 0.7 nm at 26 °C to 21 nm at 300 °C. Furthermore, a method to quantitatively determine friction coefficients via friction force microscopy was applied. The surface contact forces were calculated via the cantilever's spring constants determined using the Sader method. At scan speeds of 1.25 μm/s and 3.13 μm/s, friction coefficients of 0.60 ± 0.02 and 0.63 ± 0.01, respectively, have been obtained.