| Abstract Scope |
The measurement of thin film properties free from substrate influence remains one of the outstanding challenges in nanomechanics. Here we introduce a technique based on indentation of a supported film with a flat punch whose diameter is many times the initial film thickness. This geometry generates a state of confined uniaxial strain for material beneath the punch, allowing direct access to intrinsic stress versus strain response. For simple elastic – plastic materials this enables material parameters such as elastic modulus, bulk modulus, Poisson’s ratio, and yield stress to be simultaneously determined from a single loading curve. This confined plastic yield phenomenon has not been previously observed in thin films or homogeneous materials. We demonstrate this technique for 190 – 470 nm polystyrene films as well as PMMA and amorphous Selenium films on silicon. |