J. L. Chartier

Preparation of multi-coating PZT thick films by sol–gel method onto stainless steel substrates

PbZr0.45Ti0.55O3 ferroelectric films have been prepared by sol–gel method, using alkoxide precursor compounds and multi-layer technique. The gel films were deposited by spin-coating onto stainless steel substrates. In order to obtain crystallization in the perovskite phase, the samples were annealed at 600–700°C for 1 min. The dependence of the electric properties on the heat-treatment temperature is studied, and the coercive electric field as a function of the material thickness is determined. By SEM photography, the microstructure of the films could be shown to be homogeneous.

Nanosecond switching of ferroelectric thin films for application to a short-pulse micro electron emitter

Abstract We have analysed the electron emission characteristics from thin bulk ferroelectrics, and examined the contribution of the electrode pattern to the electric field distribution inside the ferroelectric and in the vacuum. It is shown that emission experiments performed with ferroelectric thin films up to now suffer from a not adapted electrode structure and are not optimized with respect to detection. Re-examination of the switching kinetics of ferroelectric thin films reveal that polarization can be inversed up to a certain distance from the electrode edge. Thus a first indication of the area that might participate in the emission process is found. In conclusion we discuss possibilities to improve the emission data, which may lead to the development of a micro electron-beam source based on emission from ferroelectric thin films.

Study of atomic transport mechanism of oxygen during thermal nitridation of silicon dioxide

Abstract Silicon dioxide films were nitrided at atmospheric pressure in ammonia gas at 1100°C. The atomic transport mechanism of oxygen during the nitridation was studied by using isotopic oxides (18O labeled oxides). Physico-chemical characterization of the films was carried-out by nuclear reaction analysis (NRA), secondary ion mass spectrometry (SIMS) and ellipsometry. The nitrogen incorporation in the oxide film is accompanied by a decrease of the oxygen amount. It is shown that this decrease of the oxygen amount is due to an autodiffusion phenomenon. A good fit between the calculated and experimental curves is obtained for a self-diffusion coefficient D ∗ of 3 × 10-15 cm2 s-1.

Measurement of surface potential between ferroelectric domains

Abstract A method using quantitative electron mirror microscopy is presented for measuring the difference of surface potential between ferroelectric domains. T.G.S, BaTiO3 and WO3 crystals have been studied. Between antiparallel domains of a TGS crystal, a variation of surface potential of 975 mV is measured.

Thermal nitridation of silicon dioxide at atmospheric pressure: Physico-chemical and electrical characterization

Abstract Thermal nitridation of silicon dioxide films was performed at atmospheric pressure in a furnace under NH 3 and at a temperature of 1100°C. Physico-chemical characterizations of the grown films were carried out by nuclear methods (NRA and ERD), electron spectroscopies (AES and ESCA) and ellipsometry. NRA measurements give quantitative results about nitrogen and oxygen concentrations and on the same samples AES and ESCA give the distribution of these elements throughout the films. The variation of the stoichiometry with the depth is determined. It is shown that the resulting nitroxide film is inhomogeneous with a nitrogen-rich surface layer and an interface pile-up of nitrogen. Nitridation is studied versus nitridation time and oxide thickness. The incorporation of nitrogen at the surface is higher when the initial oxide is thinner. As regards the bulk, the incorporation kinetics of nitrogen depends on the initial oxide thickness. Electrical characterizations of MIS structures realized with these nitroxide films show their good quality: flat-band voltage shifts are low; the difference in nature of interface charges is shown; conduction in the film is enhanced by nitridation as well as break-down electrical field.

Measurement of surface potential between ferroelectric domains with a quantitative electron mirror microscope

A method using quantitative electron mirror microscopy is presented for measuring the difference of surface potential between ferroelectric domains. TGS, BaTiO3 and WO3 crystals have been studied. Between the antiparallel domains of a TGS crystal a variation of surface potential of 975 mV is measured.

Pyroelectric response and thermally stimulated current of PZT-thin films

Abstract Thermally stimulated current and pyroelectric response of Pb(Zr0.44 Ti0.56)O3, thin film prepared on stainless steel substrate by sol-gel method and rapid thermal processing were studied. Pyroelectric coefficient of the film as processed amounted to p ⊂ 1.3·10−4 C/mK and the film exhibits an internal bias responsible for high density of thermally stimulated current.

Scanning electron microscopy observations and electrical study of PZT thin films

Abstract Ferroelectric thin films, mainly PZT or PLZT, are to be Increasingly used for the realisation of non-volatile ferroelectric memories (FRAMs) (1). Therefore, studies of the nature of the thin films (stoichiometry…), their deposition process and their properties (physico-chemical, electrical,…) are very important. We present here results obtained on thin films prepared by two different methods: sputtering and sol-gel.

Thermal nitridation of anodic silicon dioxide

Abstract Thin films of silicon dioxide, anodically grown in pure water, were nitrided at atmospheric pressure in ammonia gas at 1100 ° C. In-depth profiles of nitrogen were obtained by XPS. They are very different from those obtained with thermal oxides of a similar thickness, nitrided under identical conditions: the incorporation of nitrogen is more uniform in the initial anodic oxide film than in a thermal oxide film. This behaviour can be the result of a different structure between anodic and thermal oxides, as shown by the different ion milling rates.