Influence of stacking fault energy on twin spacing of Cu and Cu–Al alloys

Thick Cu and Cu–Al films were sputtered under identical conditions. A wide range of stacking fault energies (6–78 mJ m−2) were explored in order to manipulate the twin spacing and microstructure. The Cu–Al samples showed highly columnar and nanotwinned grains, while the Cu sample showed a limited number of nanotwinned grains. The effects of changes in sputtering rate were also evaluated and compared to theoretical calculations. It was observed that, contrary to predictions, the twin spacing increased at higher sputtering rates.