F.W. Shi

Ferroelectric and optical properties of Bi3.25Nd0.75Ti3O12 thin films prepared by a chemical solution method

The ferroelectric and optical properties of Bi3.25Nd0.75Ti3O12 thin films deposited on (111)Pt/Ti/SiO2/Si substrates using a chemical solution method were investigated. Bi3.25Nd0.75Ti3O12 thin films were polycrystalline and had (117) random orientation with large rod-like grains. They showed good ferroelectricity with a remnant polarization of 13.8 µC cm−2 and a coercive field of 120 kV cm−1. The dielectric constant and the dissipation factor were about 200 and 0.040, respectively, at a frequency of 10 kHz. No polarization fatigue was observed for the Pt/Bi3.25Nd0.75Ti3O12/Pt capacitor after 109 switching cycles. The optical constants (refractive index and extinction coefficient) in the wavelength range of 200–1700 nm were obtained by spectroscopic ellipsometry measurements. The optical band gap was estimated to be about 3.61 eV. The dispersion of the refractive index in the interband transition region followed the single electronic oscillator model.

Electron injection of SrTiO3∕Si interfacial layer

The electrical properties of the SrTiO3(STO)∕Si interfacial layer were studied by measuring STO metal-insulator-semiconductor (MIS) structure. The C-V measurements showed that there existed electron injection at the STO/Si interface under the higher sweep voltages. The electron injection behavior was analyzed and discussed in detail. By analyzing the voltage distribution of the semiconductor Si, the insulator STO, and the STO/Si interfacial layer in MIS structure, the electron injection electric field of interfacial layer was estimated to be about 5.5MV∕cm.

Infrared Optical Characterization of PLT Thin Films for Applications in Uncooled Infrared Detectors

Lanthanum-modified lead titanate (PLT) thin films have been grown directly on Pt/Ti/SiO2/Si (100) and LaNiO3/Si (100) substrates by a modified sol-gel method. X-ray diffraction analysis shows that the PLT thin films are polycrystalline. The infrared optical properties of the thin films were investigated using infrared spectroscopic ellipsometry (IRSE) in the spectral range of 2.5–12.5 μm. By fitting the measured ellipsometric parameter (tan Ψ and cosΔ) data with a three phase model (air/PLT/Pt) for the PLT thin films on Pt/Ti/SiO2/Si (100) and a four phase model (air/PLT/LNO/Si) for the PLT thin films on LaNiO3/Si (100) substrates, and a derived classical dispersion relation for the thin films, the optical constants and thicknesses of the thin films have been simultaneously obtained. The refractive index and extinction coefficient of the PLT thin films on Pt/Ti/SiO2/Si (100) substrates are slightly larger than those on LaNiO3/Si (100) substrates. Given the infrared semitransparent metal of Nickel currently used, the absorption of the Ni/PLT/Pt and Ni/PLT/LNO/Si multilayer thin films in this study is very large around 3.0 μm and 5.7 μm wavelength range and decrease to 15% or 20% in the 8–12.5 μm wavelength region.

Heat-treating effect on the properties of Pb1-xLax(Zr0.4Ti0.6)O3 ferroelectric thin film prepared by a modified sol-gel process

2 mol% Lanthanum doped lead zirconate titanate Pb(Zr0.4Ti 0.6)O3 ferroelectric thin film were successfully deposited by a modified sol-gel method on(111) Pt/Ti/SiO2/Si(100) substrate, the effect of heat-treatment on the properties of microstructure and ferroelectric was investigated. It is shown that deposited on (111)Pt lead to (111) preferred orientation. The PLZT thin film annealing at 700°C show good ferroelctric properties with a large remnant polarization of 40μ C/cm2, a spontaneous polarization of 75.7μ C/cm2, and a coercive field of 112kV/cm under an electric field of 650kV/cm. The dielectric constant increased with annealing temperature.