Microstructural stability of metastable amorphous and crystalline Ge1−xSnx alloys

Amorphous Ge0.75Sn0.25 films, nominally 2000 Å thick, were produced by rf sputtering. The films were transformed to polycrystalline samples with no observable phase segregated β-Sn. The mechanisms of formation of this phase and subsequent phases as a function of temperature were studied with differential scanning calorimetry and transmission electron microscopy. Through these measurements we were able to identify a volume in parameter space from which polycrystalline alloys could be nucleated and grown without simultaneous Sn segregation.