| This research focuses on the synthesis of metastable phases in thin films away from their thermal equilibrium conditions. The goal of this study is not only to achieve the desirable metastable phases, but also to understand their nucleation and growth process, so that the principles employed in this study may be applied to other material systems.; Several material systems have been used, including aluminum nitride, aluminum oxide, boron nitride and diamond. Different factors, which affect the formation of the metastable phases, have been studied. The first three materials, AlN, Al2O3 and BN were deposited using magnetron sputter techniques, while diamond was grown by direct ion-beam deposition.; The metastable phases can be obtained by different routes. Bl-AlN was stabilized in epitaxial AlN/VN (001) superlattices with an AlN layer thickness less than 4.0 nm, a so-called epitaxial stabilization effect, taking advantage of the material system itself—stabilizing the metastable phase based on the small interfacial energy between Bl-AlN and VN.; Another method to achieve metastable phases in thin films is to modify the conventional deposition techniques, i.e., increasing the ion-bombardment of the growing films. Crystalline alumina was obtained using an intensified ionized magnetron sputtering, where an increased ion-flux to the substrate was obtained using a magnetic trap generated by an external solenoid.; Cubic boron nitride (cBN) was synthesized using a similar method, i.e. ion-bombardment assisted magnetron sputtering. Factors affecting the cubic phase formation were investigated, including pre deposition vacuum, film stoichiometry, deposition temperature, and substrate bias. Study of the micro-environments of tBN prior to the cBN nucleation disclosed different types of cBN nucleation and growth associated with different film internal stress levels.; In order to precisely control the ion-bombardment during film deposition, direct ion-beam deposition was employed to study diamond nucleation on silicon. Ion beam nucleation of diamond using different reactive gas ratios leads to different nuclei qualities, which may be explained by the ion solid interaction and the effect of several competing nucleation mechanisms. |
