| The mechanical properties of brittle ZnO film and ductile Au film along with the proposed characterization methodologies are presented here.; ZnO films with thicknesses ranging from 0.202 to 1.535 mum were deposited by using the magnetron sputtering technique on Si (100) substrates 525 mum thick. Then, Vickers indentation tests were carried out on the ZnO/Si systems at room temperature, in which the applied load varied from 10mN to 2.0 N. The experimental results show that only indentation-induced radial cracking occurred in the systems with film thicknesses equal to and thinner than 0.554 mum, from which the residual stress in the films was extracted to be 387 MPa in compression. For the systems with film thicknesses equal to and thicker than 0.832 mum, only indentation-induced delamination occurred when indentation loads were low. Under high indentation loads, radial cracking concurrently occurred with delamination. The radial cracks were invisible at the film surfaces because the crack length was smaller than the delamination size. The critical film thickness for indentation-induced delamination was found to be around 0.7 mum for the ZnO/Si systems. Combining the composite hardness models with the indentation-induced delamination model, we developed a method to determine the interfacial fracture energy between a film and its substrate. The novel method is particularly useful for indentation equipment without any displacement measurement devices. Using the new method, we extracted the interfacial fracture energy to be about 12.2 J m-2 and from 9.2 to 11.7 J m-2 for the cases without and with buckling respectively of delaminated films. Consequently, the pure mode I interfacial fracture energy was calculated to be 10.4 J m-2 for the ZnO/Si systems.; In particular, we explored the phase angle and a formula was derived to calculate the phase angle of interfacial mixed mode fracture in the indentation delamination test, in which the delaminated film buckles. Interfacial fracture energy depends on the phase angle and calculating the phase angle is necessary for the determination of mode I interfacial fracture toughness.; In the section of Au film, we report a microbridge testing method for microbridge beams initially buckled by residual compressive stress. A theoretical formula is derived in closed form with the consideration of substrate deformation. Measuring the profile of a buckled microbridge beam, one can evaluate Young's modulus and residual compressive stress of the beam. (Abstract shortened by UMI.)... |
