Optical properties of Ba 0.5Sr 0.5TiO 3 thin films grown on MgO substrates by pulsed laser deposition

Abstract

Barium strontium titanate (Ba 0.5Sr 0.5TiO 3 or BST (50/50)) thin films were grown on MgO(1 0 0) substrates using pulsed laser deposition (PLD). The surface morphology of the thin films was observed using a scanning probe microscope and the grain size was found to be around 100–150 nm. The surface roughness is below 5 nm for a 250 nm thick film. X-ray diffraction (XRD) results revealed that the BST thin films were epitaxially grown on the MgO(1 0 0) substrates. Optical transmittance and electro-optic (E-O) properties of the BST thin films were measured using a phase modulation detection method. The BST/MgO configuration was highly transparent in the visible region. The BST film exhibited a predominantly quadratic E-O behavior and the quadratic E-O coefficient was found to be 0.42×10 −17 m 2/V 2.