S.B. Xiong

Fabrication and electrical properties of sol-gel derived BaTiO3 films with metallic LaNiO3 electrode

Metallic LaNiO3 (LNO) films were prepared on LaAlO3 (LAO) by metalorganic decomposition (MOD) and their application as the bottom electrode in sol-gel derived BaTiO3 (BTO) thin film was studied by means of x-ray diffraction, Raman spectroscopy, and scanning electron microscopy. BTO film on LNO-coated LAO exhibited preferred (100) orientation and smooth surface with fine grains (∼50 nm). Electrical measurements on BTO film capacitor showed good ferroelectric hysteresis, lower loss tangent and good insulating properties. These results indicated the BTO/LNO heterostructure fabricated by sol-gel and MOD technique to be a promising combination for microelectronic device applications.Metallic LaNiO3 (LNO) films were prepared on LaAlO3 (LAO) by metalorganic decomposition (MOD) and their application as the bottom electrode in sol-gel derived BaTiO3 (BTO) thin film was studied by means of x-ray diffraction, Raman spectroscopy, and scanning electron microscopy. BTO film on LNO-coated LAO exhibited preferred (100) orientation and smooth surface with fine grains (∼50 nm). Electrical measurements on BTO film capacitor showed good ferroelectric hysteresis, lower loss tangent and good insulating properties. These results indicated the BTO/LNO heterostructure fabricated by sol-gel and MOD technique to be a promising combination for microelectronic device applications.

Epitaxial Pb(Zr0.53Ti0.47)O3/LaNiO3 heterostructures on single crystal substrates

Epitaxial near‐stoichiometric ferroelectric Pb(Zr0.53Ti0.47)O3 thin films were fabricated on epitaxial metallic LaNiO3 electrodes deposited on (001) SrTiO3 and (001) LaAlO3 single crystal substrates by pulsed laser ablation. The P–E hysteresis loop of PZT in the trilayer of Ag/PZT/LNO/STO was measured using the Sawyer–Tower circuit. The remnant polarization Pr and coercive field Ec at room temperature were 30 μC/cm2 and 69.3 kV/cm (peak‐to‐peak voltage=30 V, 50 Hz), respectively.

The interaction of ambient background gas with a plume formed in pulsed laser deposition

Abstract The propagation of KrF excimer laser-produced plasmas from Pb(Zr 0.52 Ti 0.48 )O 3 has been studied with emphasis on topics relevant to the interaction of a plume with ambient gas in oxide film growth by pulsed laser deposition. A gated CCD was employed to investigate the overall shape and propagation of the laser plasma in different background gases. It is found that the plume image in both 20 Pa O 2 and Ar is spherical. With increasing O 2 pressure to 60 Pa, the plumes are prolonged along the target normal direction and suppressed in the direction parallel to the target surface. Above 60 Pa, the plumes are suppressed along both directions. When the ambient gas is Ar, the changes of the plumes are contradictious. The similarity of plume shape in 20 Pa O 2 and Ar has been interpreted as that the interaction of ablated species with ambient gas is mainly elastic. The differences are thought to be due to the interaction of ablated species with ambient gas, which is reactive in O 2 and elastic in Ar. It was proposed that the elastic scattering of ablated species by background gas leads to the nonstoichiometry of the deposited film, while the reactive collision of ablated species with ambient gas is favorable to reduce the nonstoichiometry and to enhance the oxygen incorporation in the film. It was proposed that the propagation of the ablated species can be divided into three regimes.

Pulsed laser deposition and characterization of optical waveguiding (Pb,La)(Zr,Ti)O3 thin films

The ferroelectric (Pb,La)(Zr,Ti)O3 optical waveguiding thin films have been prepared on MgO coated (100)LiF substrates by pulsed laser deposition. X‐ray θ‐2θ scans revealed that the films are single‐phase pseudocubic perovskite and highly 〈100〉 textured. The surface chemical composition of the as‐grown films was determined by x‐ray photoelectron spectroscopy. The ferroelectric properties of the films as grown on Pt/Ti coated silicon were demonstrated by using a modified Sawyer–Tower circuit, and the optical waveguiding properties of the films were characterized by using a rutile prism coupling method. The as‐grown films have an average transmittance of 75% in the wavelength range of 400–2000 nm and a refractive index of 2.2 at 632.8 nm close to the bulk PLZT. The distinct m lines of the guided TM and TE modes of the films as grown on MgO coated LiF substrates have been observed.

Pulsed laser deposition of /MgO bilayered films on Si wafer in waveguide form

Strontium barium niobate (SBN) thin films were grown on Si (111) substrates coated with MgO buffer by the pulsed laser deposition (PLD) technique. The thickness of SBN and MgO films were of the order of 1200 nm and 840 nm respectively. X-ray energy dispersive spectrometry (XREDS) showed that SBN films have stoichiometric composition identical to the target material, and no Si diffusion into the SBN film was found. X-ray diffraction (XRD) scans indicated that MgO films were highly (111) textured, but the SBN films were polycrystalline without preferential orientation. The surface of the SBN film was smooth, dense and crack-free and no large droplets were observed when studied under a scanning electron microscope (SEM). A favourable optical waveguiding property of the bilayered films was demonstrated by a prism coupler method.

Transparent PLT thin films deposited by pulsed laser deposition

Abstract Transparent Pb0.72La0.28TiO3 thin films have been deposited on (100) LiF substrates by pulsed laser deposition technique employing a KrF laser 248nm wavelength). The single perovskite target employed was prepared by sintering of the alkoxy-derived high-purity PLT powder at 1150°C. Polycrystalline PLT thin films have been grown on (100) LiF substrates under the conditions of laser fluence 2.5J/cm2, oxygen pressure 13Pa and substrate temperature 750°C. The structure, morphology and stoichiometry of the as-grown films and the employed target were characterized by XRD, SEM and EPMA technique, respectively. The optical transmittance spectrum of the as-grown thin film on LiF substrates in the wavelength range of 350 ∼ 2000nm was measured

Growth of highly c-axis-oriented Pb(Zr0.53Ti0.47)O3 thin films on LaNiO3 electrodes by pulsed laser ablation

Abstract Highly c -axis-oriented ferroelectric Pb(Zr 0.53 Ti 0.47 )O 3 (PZT) thin films have been fabricated on epitaxial metallic LaNiO 3 (LNO) electrodes deposited on (001)SrTiO 3 (STO) and (001)LaAlO 3 (LAO) single crystal substrates by pulsed laser ablation (PLA). The LNO thin film surfaces, which would influence the growth and ferroelectric properties of PZT thin films, were analyzed by X-ray photoelectron spectroscopy (XPS). P - E hysteresis loop of PZT in the trilayer Ag/PZT/LNO/STO were measured using the Sawyer-Tower circuit. The remnant polarization P r and coercive field E c at room temperature were 25.2 × 10 −6 C/cm 2 and 24.6 kV/cm (at 7.5 V, 50 Hz) respectively.

Pulsed laser deposition of c-orientedLiNbO3LiTaO3 optical waveguiding bilayered films on silicon wafers

LiNbO3(LN)LiTaO3(LT) bilayered films were grown on a p-type Si(111) wafer coated with a SiO2 buffer by a pulsed laser deposition (PLD) technique. The XPS measurement showed that the stoichiometries of the LN and LT films were in good agreement with the target materials. The crystallinity of the as-grown films was analysed by XRD, which indicated that LN and LT were highly c-oriented while the SiO2 buffer was amorphous. The surface of the as-grown films was mirror-like, dense and crack-free; no large droplets were observed by scanning electron microscope (SEM). The thicknesses of the LN, LT and SiO2 films were about 960, 360 and 1800 nm, respectively. The interface between the LN and LT films was sharp. The X-ray energy dispersive spectrometer (XREDS) analysis to the different areas of the LN film showed that there was no variation of composition with depth. The optical waveguiding properties of the films were demonstrated by a prism coupler method.

LiNbO3 phase gratings prepared by a single excimer pulse through a silica phase mask

A transmission silica phase mask grating was used to fabricate LiNbO3 wafer phase gratings by a single excimer pulse at 248 nm. The morphologies of the LiNbO3 wafer gratings were studied with an atomic force microscope as well as an optical microscope. The crystal structures of the gratings were characterized by x‐ray diffraction and three new crystal phases were found at the gratings’ surface besides the substrate phase of LN (110).

Growth and ferroelectric properties of sol-gel derived (PbLa) TiO3 films on metallic LaNiO3-coated substrates

Abstract Metallic LaNiO 3 (LNO) films were prepared on LaAlO 3 (LAO) and Si substrates by metalorganic decomposition (MOD) and their application as the bottom electrode for sol-gel derived PLT (Pb 0.85 La 0.15 Ti 0.9625 O 3 ) thin films. X-ray diffraction, scanning electron microscopy and electrical measurements were used to characterize the multilayer films of PLT/LNO/substrate. PLT films on LNO-coated LAO exhibited a strongly preferred (100)-orientation and smooth surface with fine grains (≈ 50 nm). Film capacitors with a configuration In/PLT/LNO/substrate showed promising ferroelectric hysteresis. It was found that by applying an electric field exceeding a threshold value of ≈ 250–300 kV/cm across the film, the ferroelectric hysteresis loop was enhanced significantly as a result of the poling.