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

Abstract

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 ρ decreased as their thickness tCu increased; the trend was described well using a second-order exponential function; this result suggests that ρ changes rapidly when tCu is thinner than the effective thickness teff, and changes gradually when tCu >teff.