Absence of hillock formation in epitaxial lead films

Epitaxial Pb films with double positioning have been produced by vacuum evaporation of Pb onto mica substrates maintained at 75 °C during deposition. Such films do not exhibit hillock formation when repeatedly cycled between room temperature and 77 °K or annealed at 373 °K. This is in contrast to the observation on nonepitaxial Pb films which do exhibit hillock formations when subjected to similar treatments. The difference has been interpreted in terms of grain-boundary orientation and structure.