Effect of spacer layer thickness on optical properties of [SnO 2/Mn] n and [SnO 2/Co] n discontinuous multilayers

Abstract

Multilayers (ML) of [SnO 2/Mn] n and [SnO 2/Co] n were fabricated by rf sputtering. The effect of spacer layer (SnO 2) thickness, x on the optical properties of these ML was studied. The transmittance initially decreases as x increases from 12 to 24 Å and then decreases as x increases to 36 Å. Similar trend is followed by band gap. For [SnO 2/Mn] ML, it decreases from 4.47 to 3.16 eV then increases to 4.28 eV and for [SnO 2/Co] ML, it decreases from 4.06 to 3.75 eV then increases to 4.27 eV as x changes from 12 to 36 Å. This variation is attributed to the quantum interference effects in the SnO 2 layers. The ML with x = 24 Å is found to have low defect concentration compared to the ML with x = 12 and 36 Å. The optical properties of the ML are more sensitive to the SnO 2 layer thickness than that of Mn or Co. The variation of optical properties of the present ML is an artifact of the solubility limit of Mn or Co in the interface layers.