Preferentially oriented (La, Sr)CoO₃/PbLa_0.1TiO₃ (La, Sr)CoO₃ tri-layers on lithium-fluoride and sodium-chloride substrates

Abstract

(La, Sr)CoO₃/PbLa_0.1TiO₃/(La, Sr)CoO₃ tri-layers have been grown in situ using pulsed laser deposition on single crystal LiF and NaCl substrates because of their potential to serve as substrates and sacrificial layers for building suspended infrared detector structures. At growth temperatures around 525°C to 615°C and oxygen partial pressures of ∽25 mTorr, the LaSrCoO₃/PbLaTiO₃/LaSrCoO₃ tri-layers on LiF substrates exhibit preferential orientation, as indicated by x-ray diffraction data. The surface morphology of each successive layer is smooth, as shown in scanning electron microgram. Higher growth temperatures result in better orientations but suffer from substrate out-gassing, while lower growth temperatures lead to polycrystalline film growth. On the NaCl substrates, buffer layers, such as Pt and Pd, are necessary to achieve oriented films by suppressing severe substrate out-gassing at the growth conditions required for stoichiometric (La, Sr)CoO₃/PbLa_0.1TiO₃/(La, Sr)CoO₃ tri-layer growth.

Key Words:

• Salts
• ferroelectric
• epitaxy
• infrared