Suppression of B2 phase in PdzCu1-z alloy thin films

Highlights: • Dimensional phase suppression in alloy thin film • Detection of phase boundaries using shifts in core level binding energy • High throughput analysis of alloy film composition, thickness and phase - Abstract: Thin films of pure metals and alloys can adopt phases that differ from those of the corresponding bulk alloy phase diagram. In the bulk, Pd_zCu_1-z adopts a B2 phase (CsCl structure) for 0.35 z zCu_1-z alloys with thickness p_3/2 core level shifts (CLS, ∆E_CLS^Cu(z)) across a Pd_zCu_1-z composition spread alloy film (CSAF) as a function of both composition and film thickness. In the FCC phase, the Cu 2p_3/2 binding energy decreases monotonically across the range z = 0 → 1. At T z p_3/2 CLS can be used to distinguish between the B2 and FCC phases. After annealing the Pd_zCu_1-z CSAF to 700 K, the bulk B2 phase was observed at film thicknesses >6 nm. However, at film thicknesses in the range 4–6 nm, only the FCC phase was observed. Stabilization of the FCC phase for films that are <6 nm thick may be due, in part, to surface energy effects.