H. Schmitt

Elastic and piezoelectric coefficients of TSSG barium titanate single crystals

For top seeded solution grown Barium Titanate single crystals in the tetragonal phase, the complete tensors of the elastic compliances, of the low frequency piezoelectric constants and of the coupling coefficients were determined. The method used was that of the piezoelectric resonator.

Optimization of sputtered ITO films with respect to the oxygen partial pressure and substrate temperature

Abstract The electrical and optical properties of thin films of ITO (indium tin oxide) have been optimized with respect to the oxygen partial pressure and substrate temperature. Reactive rf sputtering has been applied to a 5-inch target with 10 wt% SnO 2 and 90 wt% In 2 O 3 . After various preliminary tests, employing a biasing of −50 V and a target voltage of 1.7 kV, a target-substrate distance of 27 mm and a sputter period of 90 min were chosen. The oxygen partial pressure was varied from 0.08% to 30% of the total pressure of 3 Pa at a temperature of 400 °C. The films were investigated with an emphasis on the electrical conductivity. Using the experimentally determined optimum oxygen partial pressure (0.16%), the substrate temperature was varied between room temperature and 520 °C, and similar examinations were made of the electrical conductivity, charge carrier concentration, transmittance, selectivity, etc. The best samples had a resistivity of 2.4 × 10 −6 Ω m, a sheet resistance of 5.5 Ω, and an average transmittance of 95% in the visible spectrum without correction for reflection.

Local polarization in plzt with diffuse phase transition

Abstract In the thermally depoled state, PLZT with diffuse phase transition has no macroscopic polarization in the low temperature region. It is shown, that all anomalies of the properties discussed, can be ascribed to a local polarization.

Nanoscale imaging of elastic and piezoelectric properties of nanocrystalline lead calcium titanate

In this study the influence of the annealing conditions on the surface morphology and the elastic and piezoelectric properties of thin-film lead calcium titanate samples were investigated with enhanced atomic force microscopy techniques like tapping mode, atomic force acoustic microscopy and ultrasonic piezo-mode. The morphology of the thin-films can serve as an indicator of their properties, whether they are in an amorphous, polycrystalline and/or nanocrystalline state proving the imaging capability of dynamic force microscopy techniques.

Preparation and properties of thin ferroelectric films of PLZT

PLZT films are prepared by r f diode sputtering from a target, eight inches in diameter, manufactured by hot pressing of ceramic powder. The parameters of this process, e.g. gas pressure, substrate bias, power and excess PbO built into the target, have a great influence on the stoichiometry of the films. Substrate temperatures above 500°C during the process are necessary to obtain perovskite ferroelectric films in situ. A thermal annealing destroys the surface of the films and they can no longer be used for optical application. The ferroelectric behaviour is examined by dielectric measurements versus temperature and frequency and by studies of hysteresis loops respectively. The results are compared with the values of ceramics. The longitudinal electro-optic effect of the films is measured in transmission.

Properties of sputtered amorphous and microcrystalline GaAs films

Abstract Amorphous and microcrystalline GaAs thin films were produced by r.f. and d.c. sputtering. The films were characterized by scanning electron microscopy, electron probe microanalysis and X-ray spectrometry. Measurements of the temperature dependence of the conductivity show that variable-range hopping takes place in the grain boundaries of microcrystalline films above room temperature. In amorphous films, depending on the quality of the samples, variable-range hopping and Arrhenius conductivity was observed. Obliquely deposited amorphous and microcrystalline films showed an anomalous photovoltaic effect and, additionally, some of these samples exhibited a negative photoconductivity for illumination with high energy light ( hv

Properties of undoped and doped ferroelectric lead germanate thin films

Undoped and doped ferroelectric Lead Germanate thin films were produced by reactive sputtering. The properties of the films are dependent on several production parameters, such as substrate temperature and oxygen partial pressure in the sputter gas. It can be shown, that in the interesting concentration range of the doping materials used (e.g. Si), the production process leads to thin films with properties derivable from those of the bulk material. The results of the investigations, accentuating the ferroelectricity of the films, are presented.

Sputtered ferroelectric thin films of lead Germanate

Abstract Lead Germanate Pb5Ge011 and some of its substitutional derivatives such as Pb5(Ge1-xSix)3011 1 or (Pb5-xBax)Ge3011 are of interest because of their pyroelectric 2 and electrooptic 3 behaviour. By reactive de-sputtering we have grown thin films of Lead Germanate on several substrates. Electron probe microanalysis (EPMA) and X-ray investigations have been performed. They demonstrate that it is possible to grow stoichiometric films exhibiting the structure of the bulk. Special heat treatments have lead to a preferential straightening of the [001]-axis normal to the substrates surface. The dielectric properties of the films are well correlated to those known from ceramics and single crystals.

The dielectric relaxation of relaxor type PLZT

Abstract The dielectric properties of thermally depoled PLZT in the frequency range from 100 Hz to 13 MHz are reported, the pronounced relaxor behaviour is shown and discussed.

Preparation, properties and application of thin ferroelectric films of PLZT

PLZT films are prepared by rf diode sputtering using a ceramic target. Substrate temperatures above 500°C during the process are necessary to obtain perovskite ferroelectric films in situ. A thermal annealing destroys the surface of the films and they can no longer be used for optical application. The physical properties of the films are shortly discussed, and some characteristics of thin film transistors with PLZT films as gate insulators are shown.