Structural study of NiOx thin films fabricated by radio frequency sputtering at low temperature

Publication date: 31 January 2018
Source:Thin Solid Films, Volume 646
Author(s): Zhang Song, Tiphaine Bourgeteau, Itaru Raifuku, Yvan Bonnassieux, Erik Johnson, Yasuaki Ishikawa, Martin Foldyna, Pere Roca i Cabarrocas, Yukiharu Uraoka
Structure and crystal growth of nickel oxide thin films (10–300nm) prepared by low-temperature sputtering have been investigated by scanning electron microscopy (SEM), X-ray diffraction, and spectroscopic ellipsometry. Very thin films are compact and homogeneous and are made of almost randomly oriented crystals. A preferential growth direction is then observed following the (111), (220) and (311) planes to the detriment of the (222) and (200) planes, inducing a growth of the materials in columns perpendicularly to the substrate. An optical model able to account for this particular structure has been created from the spectroscopic ellipsometry measurements, and correlates well with the structure observed by SEM. Moreover, it enables an accurate estimation of the thickness without damage to the substrate.