Thin Film Growth of Dielectric Materials by Pulsed Laser Deposition

Thin films of SryCa1-yZr1-xTixO3 (SCZT) with x = 0.8, y = 0.01, CaHf1-xTixO3 (CHT) with x = 0.8, and xBiScO3 - (1-x) BaTiO3 with x = 0.36 (BSBT(36/64)) showing a high permittivity are useful both in capacitor applications. These dielectric thin films with a SrRuO3 (SRO) conductive bottom electrodes were prepared by using pulsed laser deposition on \u3c100\u3c La0.3Sr0.7Al0.65Ta0.35O3 (LSAT) single crystal substrates. In a search of optimal conditions to achieve epitaxially grown SCZT, CHT, BSBT(36/64), and SRO thin films, different substrate temperatures (600 C, 650 C, 750 C, and 800 C) and different partial pressures of oxygen (50 mTorr, 100 mTorr and 300 mTorr) in the chamber were used during deposition onto LSAT substrates. The optimized deposition conditions for conductive buffer layer of SRO film required 300 mTorr of oxygen partial pressure and substrate temperature of 750 C. The thorough structural and chemical studies of SCZT, CHT and BSBT(36/64) films were done by using SEM (scanning electron microscopy), AFM (atomic force microscopy), and XRD (X-ray diffraction) measurements. Sputtered gold top electrodes were added to the samples, along with etching to the SRO conductive buffer layer. These conductive electrodes were used to generate an AC electric field between the top electrodes and conductive buffer layer. Electrical characterizations of thin films such as complex permittivity, resistance and capacitance of grains and grain boundaries were performed using AC impedance spectroscopy, with curve fitting using Z-View software