Quantum size effects in Ag thin films grown on the fivefold surface of the icosahedral Al-Cu-Fe quasicrystal: Influence of the growth temperature

We have studied the growth and electronic structure of Ag thin films on the fivefold surface of the icosahedral (i)-Al-Cu-Fe quasicrystal using scanning tunneling microscopy, low energy electron diffraction (LEED), ultraviolet photoemission spectroscopy, and density functional theory. Upon deposition at 400 K, Ag islands grow to form crystallites with a preferred thickness for a given coverage. LEED patterns reveal five rotational domains of Ag crystallites with (111) orientation for coverages larger than approximately seven monolayers. Quantum well states are observed in the photoemission spectra of Ag/i-Al-Cu-Fe ranging from 5 to 35 monolayers, indicating electron confinement within the film thickness and, thus, confirming electronic growth of Ag thin films on quasicrystalline surfaces. Electronic structure calculations have been performed to discuss the possible origins of the confinement at the film-substrate interface.