Thin film capacitors with structures Au/Ba0.5Sr0.5TiO3/SrRuO3 were fabricated by pulsed laser deposition onto {001}-oriented MgO single crystal substrates. As part of an overall programme to investigate the so-called ‘dead-layer’ effect, polarisation loops were taken from the capacitors and analysed as a function of BST film thickness. Analysis was done within a Landau-Ginzburg-Devonshire (LGD) framework, and showed that for film thickness greater than ∼100nm, changes in the dielectric behaviour of the BST were dominated more by epitaxial mismatch strain, than by the conventional notion of the dead-layer.

The factors affecting optical gain were studied for Er-doped BaTiO3 thin film waveguides. Er-doped BaTiO3 with dopant concentrations of 0.3 – 9 at.% was deposited by metal-organic chemical vapor deposition. The luminescence efficiency was maximized by optimizing the growth temperature and erbium concentration as well as by post-deposition annealing. Stimulated emission was studied using the pump-probe technique over the spectral range of 1,520-1,550 nm. A maximum differential gain of 3 dB/cm was measured at 1,540 nm in an 8 mm long, 8 μm wide ridge waveguide.

Thickness dependence of leakage current behaviors was investigated in epitaxial (Ba0.5Sr0.5)TiO3 thin films with different thicknesses of 55 - 225 nm prepared on Pt(001)/MgO(001) substrates by a radio-frequency magnetron sputtering technique. Below a certain critical film thickness (≤ 55 nm), the Schottky emission is a ruling leakage conduction mechanism over a wide electric field range. In contrast, in thicker films (> 55 nm), the Schottky emission still operates at low electric fields, however at high electric fields the Fowler-Nordheim (F-N) tunneling dominates. The transition film thickness appears to be associated with overlapping of the depletion layers formed at the top and bottom electrode interfaces.

Crack free 10-μm-thick Pb1.1(Zr0.53Ti0.47)O3 (PZT) films were successfully fabricated using a chemical solution deposition process, and the ferroelectric and displacement properties were evaluated. A 0.5 M PZT precursor solution was prepared from trihydrated lead acetate, titanium iso-propoxide, zirconium n-propoxide, and 2-methoxyethanol as the solvent. The process of spin coating and pyrolysis at 500 °C was repeated five times, and then the precursor films were fired at 700 °C for 5 min. This sequence was repeated 30 times. Finally, the films were fired at 700 °C for 10 min. The fabricated crack-free PZT thick films showed (100) preferred orientation. A flat surface and dense microstructure was observed. The electrical properties were comparable with the bulk PZT ceramics. The dielectric constant and dissipation factor were εr = 1453 and tan δ = 0.039, and the remnant polarization and coercive field were Pr = 25 μC/cm2 and Ec = 30 kV/cm, respectively. Field-induced displacement of the films was measured using an atomic force microscope (AFM) with and without a top electrode using a contact mode.

We have grown SrBi2Ta2O9 (SBT) thin films on various bottom electrodes such as Pt/TiO2/SiO2/Si (Pt) and LaNiO3/Pt/TiO2/SiO2/Si (LNO) substrates. The substrate temperature and oxygen pressure for the SBT film was maintained at 500 °C and 200 mTorr. As-grown films were post-annealed at a temperature of 800 °C. X-ray diffraction studies revealed that as-grown films were amorphous and crystallized to single phase after annealing. The difficulty of obtaining lowest Raman modes of SBT on platinized silicon substrate was overcome by using conducting oxide electrodes. Films grown on platinized silicon showed maximum value of remanent polarization (2Pr ∼ 21.5 μC/cm2) with coercive field (Ec) of ∼ 67 kV/cm. The degradation of ferroelectric properties of the films was observed with the introduction of 50 nm conducting LaNiO3 electrode at the interface of Pt and SBT film, which was attributed to high resistivity of the oxide electrode layers. Leakage current density was studied with the consideration of the Schottky emission model. The barrier height of the films grown on Pt and LNO were estimated to be 1.27 eV and 1.12 eV, respectively. The reduction of barrier height was attributed to the lower work function of the LNO electrode.

Imprint describes an aging effect in ferroelectric thin films which manifests itself by a shift of the P-V hysteresis loop on the voltage axis. In this paper a mechanism is described which attributes imprint to the screening of a large electric field within a thin surface layer by electronic charges. The field at the surface arises due to the existence of a thin surface layer in which the spontaneous ferroelectric polarization is suppressed. In the course of aging this field is gradually screened by electronic charges which are generated by a Frenkel-Poole effect and then become trapped near the electrode-thin-film interface causing the shift of the hysteresis loop. A numerical simulation based on this model allows a quantitative description of the imprint effect as a function of various experimental parameters.

Piezoelectric and electrostrictive materials are potential candidates for integrated micro systems. They can be used in cantilever laminated structures for different applications, e.g. active vibration control or agile transducers [1-3]. Due to the necessity of miniaturization of MEMS devices and the reduction of process costs and time, the use of chemical solution deposition (CSD) technique with microlithography and reactive ion etching (RIE) are essential.

Within this work we used these techniques in combination with silicon bulk micro machining technique to fabricate piezoelectric Pb(Zr,Ti)O3 (PZT) and electrostrictive Pb(Mg1/3,Nb2/3)O3-PbTiO3 (PMN-PT) coated micro cantilevers with different lengths which can be used in micro switch or micro mirror applications. In general PMN shows no elastic hysteresis and a better aging behavior than PZT ceramics. Since the electrostrictive effect is smaller than the piezoelectric effect the tip deflection of PMN-PT coated beams is much lower. Cantilevers with two ceramic thin film layers and an internal electrode (bimorph) were designed and compared to such with single ceramic thin film layers (monomorph). For fabrication control and electrical characterization SEM, polarization hysteresis-, and CV-measurements were performed. Laser interferometry measurements were used to characterize the electromechanic performance of the ceramic thin films and cantilevers.

SrBi2Ta2O9 (SBT) epitaxial thin films having a mix of (100) and (116) orientations have been grown on SrLaGaO4(110) by pulsed laser deposition. X-ray diffraction θ2 θ and pole figure scans, and cross-sectional transmission electron microscopy (TEM) analyses revealed the presence of two epitaxial orientations, SBT(100) ∥ SLG(110); SBT[001] ∥ SLG[001] and SBT(116) ∥ SLG(110); SBT [110] ∥ SLG[001]. By calculating the integrated intensity of certain x-ray diffraction peaks, it was established that the crystallinity and the in-plane orientation of the (100) and (116) orientation are best at a substrate temperature of 775 °C and 788 °C, respectively, and that the volume fraction of the (100) orientation at about 770 °C reached about 60%. By scanning force microscopy and cross-sectional TEM investigations we found that the a-axisoriented grains are rounded and protrude out due to the rapid growth along the [110] direction, leading to a distinct difference of the surface morphology between (100)- and (116)-oriented grains.

We have fabricated and characterized metal-ferroelectric-metal-insulator-semiconductor (MFMIS) diodes and field-effect-transistors (FETs) using (Bi,La)4Ti3O12 (BLT) films. 9-nm-thick SiO2 is used as an “I” layer. It is shown that the memory window in the capacitance-voltage (C-V) characteristics of the MFMIS structures is as large as 3V for a voltage sweep of 5V, when the area ratio of the MIS region (SI) to the ferroelectric capacitor region (SF), SI/SF, is 15. It is also demonstrated that the MFMIS-FETs using Pt/BLT(150nm)/Pt/SiO2(9nm)/Si structures have hysteresis loops due to the ferroelectric BLT film in the drain current-gate voltage (ID-VG) characteristics. Observed threshold voltage shift is 3V and excellent data retention characteristics are demonstrated for the device with an area ratio SI/SF of 15.

A sol-gel derived Pb(Zr0.3Ti0.7)O3/PbTiO3 (PZT/PT) multilayer thin film structure has been studied for the application of infrared detection. Compared to the pure Pb(Zr0.3Ti0.7)O3 (PZT) thin film deposited by the same process, the multilayer thin film shows a lower dielectric constant and similar pyroelectric coefficient and dielectric loss. The detectivity figures of merit for the PZT/PT and PT thin films are 20.3×10−6 Pa-1/2 and 18.7×10−6 Pa−1/2, and values of voltage response figures of merit are 0.038 m2/C and 0.028 m2/C, respectively. The results show that the multilayer PZT/PT film is a better choice for pyroelectric infrared detection. Pyroelectric infrared detectors have been successfully developed based on the multilayer PZT/PT thin film. A silicon bulk-machined thermal isolation structure has been applied to reduce thermal loss from the sensing thin film to the Si substrate. To evaluate the detector performance and to aid in the thermal structure design, finite element analysis (FEA) of the detector in terms of heat transfer has been carried out by using a software package “ANSYS”. The detector response has been characterized by a modified Chynoweth system. At 7 Hz, the dynamic pyroelectric voltage responsivity is measured to be 108 V/W (in rms) with the sensing element size of 240×360 μm2. The measured results are consistent with the simulated results.

BaTiO3 (BTO) thin films with perovskite structure have been prepared on Pt/Ti/SiO2/Si substrates using a combined process of a conventional MOD (metal organic decomposition) process and a hydrothermal treatment. The BTO thin films with polycrystalline structure are grown on Pt/Ti/SiO2/Si substrates at a processing temperature of 140°C. The structural development, stoichiometry, spectroscopic, and dielectric properties of the BTO thin films have been systematically investigated. X-ray diffraction patterns show that well-developed crystallites with a pure perovskite phase have been formed. ICP (Inductively coupled plasma) and XPS (x-ray photoelectron spectroscopy) results show that stoichiometric BTO thin films were obtained.

It is known that conventional metal-oxide-silicon field-effect transistor (MOSFET) devices will have gate tunneling related problems at very thin oxide thicknesses (d ox ≤ 20 Å). In this paper we discuss the potential of polar and non-polar high-dielectric films for gate tunneling suppression and charge control. We also examine ferroelectric thickness effects in ferroelectricoxide- silicon field effect transistors (MFISFETs). Our formalism is based on a blocking-layer model for the ferroelectric film and a self-consistent solution of the Poisson and Schrodinger equations. We show that the polarization effects of ferroelectrics can allow greater controllability of the silicon interface (mobile) charge density and also the high dielectric constant effectively suppresses gate tunneling probability. In addition, the effects of ferroelectric film thickness are quite important in a MFISFET device and allow a small control of the threshold voltage. Results will be presented for the capacitance-voltage curve, tunneling probability, and leakage currents. As an example, we find for a sheet charge of 1013 cm−2, the gate tunneling probability in a MOS structure is 10−6 (d ox = 13 Å), while that in a MFISFET is 10−14 with the same equivalent oxide thickness. Our studies also show that details of the blocking layer model (dead layer thickness, coercive field, and polar charge) can be estimated from C-V measurements.

High quality BaTiO3 epitaxial thin films on MgO substrates have been grown by pulsed laser deposition (PLD). Both c-axis and a-axis orientated BaTiO3 were studied. Mach-Zehnder (M-Z) optical waveguide modulators have been fabricated by ion beam etching. The BaTiO3 waveguide propagation losses are 1-2 dB/cm. Electro-optic modulation has been demonstrated with Vπ = 6.3 V at a wavelength of 633 nm and Vπ = 9.5 V at a wavelength of 1550 nm for the aaxis samples and with Vπ = 8 V at 633 nm wavelength and Vπ = 15 V at 1550 nm for the c-axis samples. Modelling of the modulators gave the Pockels coefficient r51 = 80 pm/V for the c-axis film and an effective Pockels coefficient reff =734pm/V for the a-axis films at 633nm wavelength.

Pyroelectric properties of triglycine sulfate (TGS) thick films, separately doped with L and D alanine were investigated. Internal bias field of about 1 kV/cm, induced by the two dopants, stabilize the polarization in the opposite direction on the ferroelectric axis. Pyroelectric current (under constant stress) was recorded with a computer controlled Keithley 6517 electrometer, crossing up and down the Curie point. A reverse external electric field was applied on doped materials during heating, crossing up the Curie point. It is shown that the pyroelectric coefficient can be increased about four times at room temperature under un optimized DC electric field applied on the pyroelectric wafer.

In this paper, a novel annealing method, scanning-rapid thermal annealing (RTA), for the selectively nucleated lateral crystallization (SNLC) of Pb(Zr,Ti)O3 (PZT) thin films is discussed. The effects of lamp power and scan speed on the SNLC were investigated. It was found that scanning-RTA was very effective method for SNLC in reducing the process time and preventing undesirable nucleation at other than pre-determined positions.

We fabricated the double epitaxial layers of Ir on barrier metal ZrN for Pb(ZrxTi1−x)O3 (PZT), using reactive sputtering. In order to remove the surface oxide layer of the ZrN film prior to depositing the Ir film, we used a new treatment method, in which the ZrN film is dipped into a 0.5% buffered HF solution for less than 30 seconds and then immediately dipped into a hydrazine (N2H4) monohydrate solution for 60 seconds. Also, in order to suppress the generation of twin boundaries and to improve crystalline quality, the ZrN film is deposited using a two-step method, which consists of an initial high temperature deposition step at 850s°C followed by a lower temperature step at 600°C. On the ZrN film prepared by these methods, we can obtain a mainly (110)-oriented epitaxial Ir film.

A higher order nonlinear dielectric microscopy technique with higher lateral and depth resolution than conventional nonlinear dielectric imaging is investigated. The proposed technique involves the measurement of higher order nonlinear dielectric constants, with a depth resolution of down to 1.5 nm. The technique is demonstrated to be very useful for observing surface layers of the order of unit cell thickness on ferroelectric materials.

The feasibility of using LaVO3 as a semiconducting layer in all-oxide semiconductor/ferroelectric/conductor heterostructures was explored by growing epitaxial LaVO3/(Ba,Sr)TiO3/(Pb,La)(Zr,Ti)O3/(La,Sr)CoO3 heterostructures on (001) LaAlO3 single crystal substrates by pulsed laser deposition. A high degree of c-axis orientation and strong in-plane texture revealed by x-ray diffraction indicated the epitaxial crystallographic relationships between the layers. With a 30 nm layer of (Ba,Sr)TiO3, the heterostructure showed optimal ferroelectric hysteresis with remanent polarizations over 30 C/cm2. The capacitance measurement as a function of voltage might reveal the modulation of the depletion layer in the semiconducting LaVO3.

Paraelectric BaxSr1−xTiO3 (BST) (x = 0.5 and 0.6) thin films are attractive candidates for the fabrication of various microwave dielectric devices including phase shifters, resonators, filters, oscillators etc. In the present work we have studied the effect of annealing temperature and ambient on the epitaxial quality, surface morphology, dielectric, and phase shifter characteristics of BST thin films deposited on LaAlO3 substrates. The epitaxial quality of the film was markedly improved as the annealing temperature was increased from 1050 to 1100°C. The degree of phase shift increased from 221 to 328° (measured at 14.5 GHz applying a field of 30V/μm) with the improvement of the epitaxial quality of the film. The insertion loss was also increased with the increase in annealing temperature and therefore the effective phase shifter κ factor (defined by the ratio of the degree of phase shift and insertion loss) remained low (∼30°/dB), while annealing these films in N2 ambient significantly reduced the insertion loss, their dielectric breakdown was observed at relatively lower applied voltage as compared to air and oxygen annealed films. The observed electrical behavior was correlated with the composition, chemical state of the constituents and epitaxial quality of the films synthesized under different annealing conditions.

Alternating current conduction in BaBi2Nb2O9 (BBN) thin films has been studied over a wide range of temperatures and frequencies. A power law relation was used to explain the frequency dependence of ac conductivity. In the higher frequency region, ac conductivity of the BBN thin films was temperature independent. The activation energy calculated from the Arrhenius plot of ac conductivity was found to be around 0.25 eV. It was attributed to shallow trap controlled space charge conduction in the bulk of the sample. The impedance analysis of the BBN thin films was also performed to gain insight into the microstructure of the films, including the characteristics of the grains, grain boundaries, and film-electrode interface. The response of a single RC combination has been observed for our case. The effect of other components, such as the grain boundary interface and electrode/film interface was negligible. The imaginary component of impedance (Z”) exhibited different peak maxima at different temperatures. A Debye mechanism was found to be appropriate to explain the polarization relaxation in BBN thin films.