Temperature-induced phase separation in chromium films

Abstract

Vacuum evaporation of chromium on Si(100) results in an interfacial nanophase layer followed by a mixed grain region. In this work, the mixed grain region in chromium is nearly transformed into a single-phase region, which resulted in a maximum phase separation between the nano-δ-A15 phase and bulk α-bcc chromium. It is achieved by creating a temperature gradient across the chromium–silicon interface by using rapid evaporation at a growth rate of ∼3 μm/min at a source-to-substrate (SS) distance of 2 cm. Separately grown nanophase chromium films at SS distance of 32 cm show a predominant δ-A15 phase. Short-SS-distance rapid evaporation has the potential to produce selective phase separation by combining the temperature gradient with interfacial stress.