Structural characteristics and mechanical properties of Ti(Cr) films produced on Si substrate

Abstract

A series of nanogranular Ti 90Cr 10 thin films have been fabricated by pulsed-laser deposition on Si substrates at different temperatures. The crystal structure and mechanical properties of these films were investigated. The X-ray diffraction and transmission electron microscope images with selected area diffraction showed that the structure of as-prepared films is dependent on film thickness and deposition temperature. It was found that the Ti 90Cr 10 films consisted of fine hexagonal close packed microstructure with columnar grains, while body close-packed cubic structure of Cr films are composed of irregular grains, meanwhile, a chromium disilicide (CrSi 2) layer formed in the interface between the substrate and Cr films which deposited at temperature of greater than 600 °C. The crystalline and columnar grains improved with an increase of the thickness of the films and an optimum microstructure is obtained under the present experimental condition of about 50 nm thickness and deposited temperature of 500 °C for Ti 90Cr 10 films. Deposited at 300 °C, the Ti 90Cr 10 films have hardness of 12.7 GPa and elastic modulus of 174.6 GPa. Improved to 600 °C the sample shows higher hardness of 13.1 GPa and higher elastic modulus of 183.2 GPa. Using Benjamin–Weaver model, adhesion shearing force can be calculated as 34.9 MPa for 300 °C Ti 90Cr 10 film while higher value of 44.4 MPa for higher temperature of 600 °C.