Submicron eutectic thin-film structure

Abstract

Pb-Sn, Cd-Pb, and Al-Al2Cu eutectic thin films were directionally solidified at rates between 0.0015 and 0.15 cm/sec with both a lamp and a laser heat source to fabricate fault-free submicron periodic structures. A transition from lamellar to cellular structures with increasing solidification rate was observed with a thermal gradient of 200 °C/cm applied with the lamp heat source. Cells did not form with the increased thermal gradient produced by the laser heat source, 8000 °C/cm. Spacings as fine as 0.1 μ were observed in the Cd-Pb eutectic. A maximum theoretical growth rate was estimated which corresponds to a spacing of 80 Å.