Microstructures induced in germanium-rich GeAl films by laser-induced melting and rapid solidification

We report metastable phase formation in germanium-rich Ge1-xAlx amorphous films (x = 0.35 and 0.24) induced by laser melting. The results show that the nucleation phase for solidification is germanium and that germanium faceted crystals and dendrites are formed. The four known metastable crystalline phases of GeAl are observed and compared with those obtained by other rapid solidification techniques. For the range of compositions in the present study, the hexagonal phase is found to nucleate the rhombohedral phase and it is the first time that the orthorhombic phase is found as a consequence of a melting-solidification process. © 1990.