Anisotropic phase separation through the metal-insulator transition in amorphous alloys.
The characterization of nanometer-scale phase separation in sputtered, amorphous, metal-Ge and Fe-Si films has led to the observation of a new microstructure that extends through the metal-insulator transition. The phase separated regions, which are dependent on deposition conditions, are well correlated and of the order of 1 nm in the growth plane but poorly correlated and 1.5--2.0 nm in the growth direction. The results suggest that fluctuations during film growth play a pivotal role in preventing anticipated columnar structures, probably leading to unusual percolation properties.