摘要:

The process of the production of LiNbO3thin films by sputtering onto cold silicon substrates followed by heat treatment was investigated. Composition, structure and physical properties of the films were investigated using light refractive indices, −2 X-ray diffraction and scanning electron microscopy, capacitance and dielectric constant measurements. The amount of the crystalline phase of the stoichiometric composition was found to be about 90%. The refractive index (λ = 632.8 nm) and the dielectric constant of the best samples were as high as 2.28 and 40, respectively. Insulating properties of this film structure were studied by SEM using e-beam sample charging. The potential images of the film structure provided evidence that current leakage takes place in the boundary areas between the crystallite and noncrystallite phases.

ISSN:1058-4587    

DOI:10.1080/10584589508219660

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Thin films of lead zirconate titanate having the composition Pb1.05(Zr0.53Ti0.47)O3were deposited by a solgel method on a set of crystalline and amorphous substrates. The thickness of the film was varied by controlling the sol concentration or by repeated coatings. Factors controlling phase formation in the films such as nature of the substrate material, film thickness, chemical composition of the film, heating rate and gaseous atmosphere during the heat treatment were studied. On glass substrates the pyrochlore phase was obtained in thin (0.4 um) films and the perovskite phase in thicker (>1.5 um) films. Crystalline substrates (except Si and stainless steel) yielded a perovskite phase in 0.6 um thick film. Low Zr/Ti ratio, rapid heating and introduction of nitrogen in the later stage of heat treatment also favoured the formation of the perovskite phase. It is shown that Pb deficiency in the film caused by diffusion of Pb into amorphous substrates or by other mechanisms is primarily responsible for inhibiting the pyrochlore to perovskite transformation. The initial crystallisation of the amorphous film into pyrochlore rather than a perovskite phase (as in powders) is proposed to be due to higher strain energy barrier which exists for the amorphous to perovskite transformation in the film.

ISSN:1058-4587    

DOI:10.1080/10584589508219661

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The bulk photovoltaic effect (BPE) has been investigated in lead zirconate titanate (PZT) thin films. Measurements of the kinetics, spectral distribution and photocurrent hysteresis loops have been made. In the extrinsic spectral region, the steady-state photocurrent is primarily due to the BPE, where the photovoltaic tensor component has been determined to be G31= 10−9cm/V. However, in the intrinsic region, the BPE has not been determined due to the strong contribution from photoinjection currents. Finally, it is shown that the BPE may be the driving force for photoinduced hysteresis changes in PZT thin films, particularly in the extrinsic spectral region.

ISSN:1058-4587    

DOI:10.1080/10584589508219662

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ferroelectric PbTiO3thin films have been epitaxially grown on (100) NaCl cleavage surface by MOCVD using tetraethyllead and titanium isopropoxide as precursors. The microstructures and epitaxial characteristics of as-grown thin films were investigated by means of transmission electron microscopy. TEM studies have shown that the epitaxial thin film was highly (001) oriented and even near single-crystal epitaxy if without a small volume of 45° rotated grains, the average grain size is around 1000 A. Lowangle grain boundary formed universally when islands coalesced during the early stage of epitaxial growth. A possible growth mechanism has been given to explain this epitaxial phenomenon by consideration of two-dimensional coincidence superlattice. 90° ferroelectric domains were also observed both in the large matrix grains and small 45° rotated grains.

ISSN:1058-4587    

DOI:10.1080/10584589508219663

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two types of potential bottom electrode structures for integration of ferroelectric materials in DRAM technology have been investigated: one based on iridium, the other based on platinum alloyed with oxygen gettering elements, such as B and Ti. The electrode structures, deposited on Si substrates, have been annealed in oxygen at 650°C for 30 min and characterized by RBS and AES. It was found that alloying the Pt with 3% of alloying elements had no beneficial effect and did not improve the properties of Pt as a barrier to oxygen diffusion. At the investigated annealing conditions, oxygen diffuses through Pt or its alloys and oxidizes the underlaying material. On the other hand, a thickness of 1100 Å of Ir was found to provide a barrier to oxygen diffusion under the same conditions. A layer of Ta in contact with Pt or Ir was found to deteriorate the barrier properties of both metals at the investigated annealing conditions.

ISSN:1058-4587    

DOI:10.1080/10584589508219664

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Pb(ZrxTi1−x)O3(PZT) based ferroelectric capacitors have been produced at 600°C on R-cut sapphire and Si-doped (100) GaAs substrates using a pulsed laser ablation deposition (PLAD) technique. La0.5Sr0.5CoO3(LSCO) conducting electrodes deposited using PLAD serve as top and bottom electrodes. X-ray diffraction results show that the PZT film is polycrystalline and phase-pure in both cases. Electrical characterization of the films show remanant polarization in excess of 20 μC/cm2. Results of long term properties show that these capacitors: are very tolerant to extremely large numbers of switching cycles; retain charges over very long periods of time; and do not show a strong tendency for their dipoles to be imprinted in a preferred direction.

ISSN:1058-4587    

DOI:10.1080/10584589508219665

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An empirical electrical equivalent circuit for dielectric thin films, based on experimental data, is developed. Current responses to voltage-steps and to voltage-ramps are calculated and compared with experimental data. The simulation allows us to separate current contributions of different physical processes while the experiment only reveals the sum of the currents.

ISSN:1058-4587    

DOI:10.1080/10584589508219666

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effects of elevated temperature on the long and short term ferroelectric properties of La0.5Sr0.5Co3(LSCO)/PbZr0.53Ti0.47O3(PZT)/La0.5Co3(LSCO) heterostructure capacitors are presented in this paper. Capacitors are evaluated in the temperature range of 25°C to 100°C. Polarization values (switched and non-switched), coercive voltages, and PZT resistivity are measured as a function of temperature. Rate of fatigue, tendency to imprint, and retention loss are also investigated in the 25–100°C temperature range. An activation energy for the process responsible for loss of remanent polarization is determined from the fatigue data.

ISSN:1058-4587    

DOI:10.1080/10584589508219667

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor