Nanotribological behavior of ZnO films prepared by atomic layer deposition

• We evaluated the nanotribological response of ALD ZnO films.
• ZnO films compressed by an indenter via a ramped force exhibited friction coefficient oscillations.
• Significant suppression of sliding deformation induced pile-up for ZnO films subjected to thermal annealing.

We used atomic layer deposition to form ZnO thin-film coatings on Si substrates and then evaluate the effect of pile-up using the nanoscratch technique under a ramped mode. The wear volume decreased with increasing annealing temperature from room temperature to 400 °C for a given load. Elastic-to-plastic deformation occurred during sliding scratch processing between the groove and film for loading penetration of 30 nm. The onset of non-elastic behavior and greater contact pressure were evident for loading penetration of 150 nm; thus, full plastic deformation occurred as a result of a substrate effect. We suspect that elastic–plastic failure events were related to edge bulging between the groove and film, with elastic–plastic deformation attributable to adhesion discontinuities and/or cohesion failure of the ZnO films.