Nanoscale Observation of a Grain Boundary Related Growth Mode in Thin Film Reactions

Abstract

We report the atomic scale observation of a thin film growth mode related to grain boundaries in multilayers of polycrystalline gold and amorphous silicon. Using differential scanning calorimetry, in situ x-ray diffraction, and high-resolution electron microscopy, we observe silicide nucleation to take place at grain boundaries in the polycrystalline gold films followed by lateral silicide growth parallel to gold/silicon interfaces. This growth mode is related to solid-state reactions at low temperatures where atomic transport is restricted to grain and interphase boundaries. It demonstrates the importance of thin film microstructure for phase selection during thin film reactions at low temperatures.