Time-resolved high-resolution transmission electron microscopy and high-angle annular dark field scanning transmission electron microscopy of metal-mediated crystallization of amorphous germanium films

Metal mediated crystallization of amorphous germanium (a-Ge) films was studied through ‘in-situ’ heating by time-resolved high-resolution transmission electron microscopy (HRTEM) and high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), mainly on a-Ge films with nanometer-sized gold clusters on the surfaces. It was revealed from the dynamic HRTEM observations that the interface between crystalline gold and a-Ge was a bit melted due to alloying even at 70°C and liquid-like gold-rich alloys migrate on the a-Ge films to initiate the crystallization, which was confirmed also through the static observations with HAADF-STEM.