Ion assistance in epitaxial growth as a strategy to suppress twinning

Homoepitaxy on Ir(111) at 350 K through physical vapor deposition without and with ion assistance is compared in a scanning tunneling microscopy study. During growth without ion assistance thin Ir films on Ir(111) rapidly develop stacking faults such that for films of more than 50 atomic layers thickness the majority of the film surface displays twins. Ion assistance with 100 eV Ar+ at normal incidence as well as with 500 eV Ar+ at grazing incidence both effectively suppress stacking fault formation and twinning in the growing film. The mechanisms of twin suppression are identified.