Nanoindentation-induced interfacial fracture of ZnO thin films deposited on Si(111) substrates by atomic layer deposition

Abstract

The structural and nanomechanical characteristics of ZnO thin films grown on Si(1 1 1) substrates by using the ALD process are investigated by combining XRD, AFM and Berkovich nanoindentation techniques. Results indicated that the ZnO/Si(1 1 1) thin films also exhibited clear evidences of fracture behaviors-induced pop-in phenomenon in the load–displacement curve during nanoindentation. Moreover, based on the analysis of the energy release in cracking, the fracture toughness of ALD-derived ZnO thin films deposited on Si(1 1 1) substrates is calculated. • ZnO thin films are deposited on Si(1 1 1) substrates using atomic layer deposition. • The interfacial fracture behaviors for ZnO thin films are characterized by Berkovich nanoindentation. • The fracture toughness of ZnO/Si(1 1 1) thin films is about 3.1 MPa m 1/2 . In this study, the structural and nanomechanical characteristics of ZnO thin films are investigated by mans of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques. The ZnO thin films are deposited on Si(1 1 1) substrates by using atomic layer deposition (ALD). The interfacial fracture behaviors for ALD-derived ZnO thin films are characterized by Berkovich nanoindentation, and the morphologies of indentations are revealed by using scanning electron microscopy (SEM). During nanoindentation, the interfacial fracture of ZnO thin films is significantly observed as the indentation load reaches 50 mN and, the corresponding loading segment in the load–displacement curve displays an obvious discontinuity event. Based on the analysis of the energy release in cracking, the fracture toughness of ALD-derived ZnO thin films deposited on Si(1 1 1) substrates is calculated.