RBS/channeling analysis of epitaxial films with Nb buffer layer on sapphire substrate

Abstract

Epitaxial Cu(1 1 1), Al(1 1 1) and Sc(0 0 0 1) films were successfully grown on α-Al 2O 3(1 1 2 ̄ 0) substrates with a high quality Nb(1 1 0) buffer layer by electron beam evaporation technique. Films were analyzed by RBS/channeling and X-ray diffraction techniques. The Cu(1 1 1) film and Al(1 1 1) film on the Nb(1 1 0) buffer layer have twinned structure, which is rotated by 180° with each other around the 〈1 1 1〉 direction. The crystal quality of Cu(1 1 1) layer was improved with the increase of Nb(1 1 0) buffer layer thickness and then saturates at the high quality after about 2 nm thickness. The substrate temperature for the high quality Nb(1 1 0) buffer layer on the α-Al 2O 3(1 1 2 ̄ 0) is 750 °C, and that for the Cu(1 1 1) film on the Nb(1 1 0) buffer layer is 200 °C. The good epitaxy has been realized in Al(1 1 1) and Sc(0 0 0 1) films on Nb(1 1 0) layers at 95 and 300 °C, respectively.