Growth of Fe cubical particles on substrates during gas flow sputtering

Abstract

The shape of Fe fine particles formed during gas flow sputtering was examined. Simultaneous formation of truncated dodecahedron particles with an average size of 80 nm and small particles with an average size of 20 nm was observed in an Ar gas flow. Truncated dodecahedron particles deposited on a substrate were observed to grow and change their shape as a result of collisions with the small particles. Under conditions of short substrate-target separation or a high gas flow rate, particles with a novel shape and possessing {100} facets of a body-centered-cubic structure and a staircase-like structure on the edges of the cubes were formed. On the other hand, under conditions of long substrate-target separation and a low gas flow rate, aggregated particles, which were almost round particles covered with smaller particles, were formed. This behavior is explained by the kinetic energy of the small particles, termed “gas flow energy” in this paper, which is a function of the velocity of the small particles prior to colliding with the truncated dodecahedron particles on the substrate.