Fracture toughness of ultra-thin atomic layer deposited alumina films

Abstract

This study investigates the cracking and interfacial adhesion of atomic layer deposited alumina films on as-received and plasma treated polycarbonate substrates when subjected to controlled externally applied stresses. Optical microscopy was used to observe and follow crack evolution and delamination of the alumina film from the substrate during tensile loading with a small mechanical testing device. The strength and toughness of the alumina film (thickness = 140 nm) was determined to be 140 MPa and 0.23 MPa.m1/2, respectively. It is shown that the adhesion of the alumina films was dramatically improved for the plasma pre-treated substrates.