Electrodeposition of Bi_1-xSb_x thin films

Abstract

Bismuth and antimony are semimetals with a rhombohedral crystal structure and similar lattice parameters. Bi1-xSbx alloys exhibit unusual electronic properties and are of interest for thermoelectric and magnetoelectronic devices. In this paper, we show that Bi1-xSbx alloys can be electrodeposited from acidic chloride-based solutions and that a homogenous solid solution is obtained across the entire composition range. We show that bulk deposition is preceded by monolayer deposition at potentials negative to the equilibrium potential. The deposition/stripping reaction for bismuth is more reversible than for antimony leading to a small increase in the bismuth concentration in films compared to the concentration in solution at low Sb(III) concentrations. Thin films have a preferred (012) texture and the interplanar spacing is proportional to the film composition according to Vegard's rule. The grain size for thin films increases from about 1 μm for pure Bi to several micrometers for pure Sb.