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Some results on the microstructure controlling and characterization of ferroelectric thin films for uncooled infrared detections are presented. Several novel technologies have been developed to control the microstructures, e.g., grain size, grain shape, and the texture of BST, PZT thin films as well as to fabricate PZT thin films at low temperature. 256 × 1 pixels infrared detector has been prepared and used to realize infrared thermal image. A highly self-polarization in PMNT relaxor films has been observed. A novel readout method with infrared-visible transition mechanism is also discussed.

Quasiperiodic Ba0.9Sr0.1TiO3 (BST) multilayers have been fabricated on SrTiO3 substrates by using chemical solutions containing polyethylene glycol (PEG), and effect of PEG content on optical properties of the BST multilayers have been investigated. Each multilayer with a single perovskite phase displays a layered structure consisting of dense and porous BST layers. It is found that the central wavelength of the reflection-band for BST multilayers shifts to longer wavelength with increasing the PEG concentration within a given polymer amount range. With the same numbers of period and processing condition, the BST multilayers derived from chemical solutions containing PEG additives with a relative molar amount of 0.5, exhibit the highest optical reflectivities.

The magnetic properties of Ni-doped monolayer MoS2 are investigated using the density function theory. The results show that two Ni-doped systems of the nearest-neighbor configuration are ferromagnetic. The p–d hybridization between the Ni dopant and its neighboring S atoms results in the splitting of energy levels near the Fermi energy. These results suggest the p–d hybridization mechanism for the magnetism of the Ni-doped MoS2 monolayer. The magnetic moment disappears with increasing Ni–Ni distance. Our studies predict the nearest two-Ni-doped MoS2 monolayers to be candidates for thin dilute magnetic semiconductors. Moreover, the formation energy calculations indicate that it would be easier to incorporate Ni atoms into a S-rich MoS2 monolayer in the experiment.

The infrared absorption spectra have been measured at temperatures from 4.2 to 300 K for thin bulk samples of Hg1−xCdxTe with compositions, x, from 0.170 to 0.443 with thicknesses smaller than 10 μm. The spectral range of the investigations includes the exponential absorption edges and intrinsic absorption spectra determined by electron transitions from the valence band to the conduction band. From the measured absorption spectra, the energy‐band gap was determined by the photon energy at the absorption transition point between the Urbach exponential region and the Kane region. The data were fitted by a calculation of the intrinsic optical transition using Kane’s theory. The dependence of the energy‐band gap on composition and temperature was determined in the alloy composition range from x=0 to 0.443 and for x=1, for temperatures from T=4.2 to 300 K. The absorption coefficient, αg, at the band‐gap energy versus composition and temperature, and the exponential rule satisfied by the absorption edge are als...

Mn 1.56 Co 0.96 Ni 0.48 O 4 films with spinel structure for infrared detection are prepared on Al 2 O 3 substrate by chemical solution deposition method. The resistance vs temperature (R-T) characteristics at 130~304 K temperature range and infrared transmission spectrum (1-10 m) are measured and temperature coefficients of resistance (TCR) are calculated. The conduction process can be explained well by hopping conduction. At low temperature nearest neighbor hopping (NNH) mechanism fits the data well, while at high temperature, variable range hopping (VRH) mechanism dominates the system, and this transition temperature is at about 200 K. The value of TCR is about -3.73% K -1 at 300 K. Mn 1.56 Co 0.96 Ni 0.48 O 4 films exhibit a strong absorption around 2 m which is considered to be corresponding to the gap of energy bands showed by infrared transmission spectrum. The band gap obtained from the transmission spectrum data using the Tauc’s law is ~0.567 eV. Keywords: spinel, Infrared detection, Hopping conduction, Negative temperature coefficients, transition metal oxides.

The BaTiO3 and Mn:BaTiO3 thin films were fabricated on fused quartz and Si(111) substrates by a sol-gel method. The crystal structures of the samples were characterized by x-ray diffraction. It is shown that the samples are both polycrystalline thin films and possess cubic structure. The Mn-doping has no obvious effect on the crystal structure. The optical properties of the thin films were studied by transmitted spectrum technique or by spectroscopic ellipsometry depending on the substrate used. The transmitted spectrum shows that the absorption edge of the Mn-doping films has red shift compared with the undoping films. The energy gaps calculated from the transmitted spectrum are 3.68 and 3.39eV for undoping and Mn-doping samples, respectively. The results of spectroscopic ellipsometry shows that the refractive index of the Mn:BaTiO3 thin film is bigger than that of the BaTiO3 thin film. Which the change of energy gap and refractive index caused by Mn-doping can be explained by the Sellmeier Oscillator model.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The structure and ferroelectric properties of Bi3.25 La 0.75Ti3O12 (BLT) and Bi3.25 Nd0.75Ti3O12 (BNT) thin films deposited on (111)Pt/Ti/SiO2/Si substrates using a metalorganic decomposition (MOD) method were investigated. Both the films were polycrystalline structure with the single bismuth-layered phase. The BNT film showed the (117) random orientation, while the BLT film displayed (00l )-preferential orientation. The BNT film showed a larger remnant polarization (~13.8μC/cm2) than the BLT film (~3.5μC/cm2), while both films displayed almost the same value of coercive field. The BNT film had the larger dielectric constant and a litter larger dissipation factor than the BLT film. The superior ferroelectricity of the BNT film was mainly attributed to its (117) random orientation. Furthermore, the BNT film displayed good fatigue endurance up to 109 switching cycles, indicating it was a useful candidate for integrated device applications.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

92%Pb(Mg1/3Nb2/3)O3-8%PbTiO3 (PMNT) thin films on Pt/TiO2/SiO2/Si substrates with and without a LaNiO3 (LNO) buffered layer have been prepared using a sol-gel method. Structures and electrical properties of these two films have been investigated and compared. Highly (111)-oriented PMNT thin films with some amounts of pyrochlore phase are obtained on bare Pt electrodes. On the contrary, (100)-oriented PMNT thin films with pure perovskite phase are formed on Pt electrodes with a LNO buffered layer. Electrical properties of the PMNT thin films are highly improved by using the buffered layer LNO. It is found that the remanent polarization (P r) and the dielectric constant for the PMNT film with a LNO buffered layer are larger than that for the film without a LNO buffered layer.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

2 mol% Lanthanum doped lead zirconate titanate Pb(Zr 0.4 Ti 0.6 )O 3 ferroelectric thin film were successfully deposited by a modified sol-gel method on(111) Pt/Ti/SiO 2 /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 orie ntation. The PLZT thin film annealing at 700 0 C show good ferroelctric properties with a large remnant polarization of 40µ C/cm 2 , a spontaneous polarization of 75.7µ C/cm 2 , and a coercive field of 112kV/cm under an electric field of 650kV/cm. The dielectric constant increased with annealing temperature. Keywords: ferroelectric thin films; sol-gel; remnant polarization ; coercive field; 1. INTRODUCTION Lead-based ferroelectric thin film , e.g., PbTiO 3 (PT), Pb(Zr x Ti 1-x )O3 (PZT), Pb 1-x La x (Zr y Ti 1-y )O 3 , have been show to be of major technological interests due to their promising potential for applications such as pyroelectric detectors, piezoelectric vibrators, electric-optical devices and nonvolatile random access memories. Many processing routes for PZT thin film, including laser ablation[1], rf spu ttering[2], CVD and solution deposition methods, have been reported. Among those methods, Sol-gel processing is a very attractive methods, it has many advantages such as easily controlling stoichiometry and microstructure, relatively lo w processing temperature and quite simple processing. The substrate heterolayer structures usually used are based on Pt/Ti/SiO