Epitaxial growth and characterization of Cu thin films deposited on Al2O3(0001) substrates by magnetron sputtering

Epitaxial Cu thin films were grown on Al2O3 (0001) substrate by radio frequency magnetron sputtering. The epitaxial relations were found to be Cu(111)//Al2O3(0001 Cu[1_0]//Al(0001 Cu[1_0]//Al2O3[1_100] in the out-of-plane direction and Cu(1_10)//Al2O3(11_20), Cu[111]//Al2O3[0001] in the in-plane direction. Oxygen adsorbed from the air does not affect the structure of Cu/Al2O3(0001) epitaxial thin films. The evolution of the surface roughness can be described by a dynamic scaling exponent. In these Cu/Al2O3(0001) epitaxial thin films, the electrical resistivity rho decreased as their thickness t(Cu) increased; the trend was described well using a second-order exponential function; this result suggests that rho changes rapidly when t(Cu) is thinner than the effective thickness t(eff), and changes gradually when t(Cu) > t(eff). (C) 2021 The Authors. Published by Elsevier B.V.