A transmission electron microscope study of microstructural development in magnetron-sputtered MoSi2 thin films

Transmission electron microscopy has been used to reveal the microstructural development in magnetron-sputtered MoSi2 films. Both 50 nm thick free-standing films and 1 μm thick films on (001)Si exhibited similar microstructures. The as-deposited films were amorphous. Annealing at 700 °C resulted in the crystallisation of heavily faulted, fine, untextured grains of the metastable hexagonal C40 MoSi2 phase. Annealing above 800 °C led to the polymorphic transformation of the C40 phase to the equilibrium tetragonal C11b MoSi2 and D8m Mo5Si3 phases. The C11b grains contained high densities of coherent {112}<111> twins on {110}. It was deduced that the C11b phase was produced from the C40 phase by a massive transformation with coherent growth twins formed by “double positioning” on {110} facets at the advancing transformation front.