Preparation of Pb–Bi film by alloy evaporation II. Microstructure and morphology

In a previous paper, techniques were developed to obtain hexagonal‐close‐packed (27–32 wt.% Bi) Pb–Bi alloy films by evaporating from an alloy source. For the work reported here, Pb–Bi films were prepared under various evaporation rates, substrate temperatures, and residual gas pressures with a goal to obtain smooth and fine‐grained films. Contrary to what is generally expected, the grain size, as measured at room temperature after sample warm up, increased by a factor of 3 to 5 when the substrate temperature Ts was lowered from 273 to ∼180 K and below. Evidence to be presented suggests that although fine grains were obtained at low Ts, significant grain growth had occurred when the films were warmed from Ts<200 K to room temperature. Grain sizes of Pb–Bi films prepared at 77 K were reduced when the films were doped with H20 during deposition or seeded with 5–10 nm thick layers of Pb–Bi or O2‐doped Pb. But no grain size reduction was observed for films doped with O2 at 77 K or seeded with Au or Pd at 273 ...