摘要:

The dielectric and electrical properties of excimer laser ablated processed paraelectric (Ba0.5, Sr0.5)TiO3, ferroelectric Bi-layered SrBi2(Ta0.5Nb0.5)2O9, and antiferroelectric (PbZrO3) thin films have been investigated. The effect of processing parameters on the microstructure of the films and the functional properties has been presented in detail. Some of the recent studies of stress induced effects, dielectric, hysteresis and ac and dc electrical properties have been highlighted in conjunction with microstructures of the films.

ISSN:1058-4587    

DOI:10.1080/10584580008215635

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

SrBi2Ta2O9(SBT) is an attractive material for nonvolatile ferroelectric memory applications. In this paper we report on the deposition of highly epitaxial and smooth SrBi2Ta2O9films on (110) SrTiO3substrates. The films were grown by pulsed laser deposition at temperatures ranging from 600 to 800°C and at various laser fluences from a Bi-excess SBT target. The background oxygen pressure was maintained at 28 Pa during the film deposition. Structural characterization of the films was performed by x-ray diffraction. Atomic force microscopy was used to investigate morphology and growth of the films. The films grew with preferred (115) or (116) orientation. The roughness was of the order of unit cell height. The films display a growth pattern resulting in corrugated film morphology.

ISSN:1058-4587    

DOI:10.1080/10584580008215636

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Ferroelectric SrBi2(Ta, Nb)2O9(SBTN) thin films were prepared by rf magnetron sputtering utilizing a multi-chamber type production tool (ULVAC CERAUS ZX1000). Accurate and dynamic compositional control results in excellent ferroelectric performances such as large 2Pr up to 15μC/cm2, fatigue free at least 109cycles as well as good uniformity and process repeatability. These results indicate that the SBTN sputtering process is promising for ferroelectric memory production.

ISSN:1058-4587    

DOI:10.1080/10584580008215637

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Highly c-axis oriented single phase Na0.5K0.5NbO3(NKN) thin films have been deposited onto polycrystalline Pt80lr20substrates and SiO2/Si(001) wafers using pulsed laser ablation of stoichiometric ceramic target. Strong self-assembling of NKN films along the [001] direction has been observed. Properties of NKN/Pt thin film structures have been successfully tailored by oxygen pressure control from the ferroelectric state, characterized by the remnant polarization of 12 uC/cm2, dielectric constant ε ∼ 520 andtanδ ∼ 0.024 @ 100 kHz, to superparaelectric state withtanδ as low as 0.003 and ε = 210 with very small 1.7% dispersion in the frequency domain 0.4–100 kHz and less than 10% variation in the temperature range 77–415 K. NKN films grown onto SiO2/Si(001) substrates show quadrupled super-lattice structure alongc-axis, losstanδ less than 0.01, and ε ∼ 110 @ 1 MHz.C-V measurements for Au/NKN (270nm)/SiO2/Si MFIS-diode structure yield memory window of 3.26 V at the programmable voltage of 8 V.

ISSN:1058-4587    

DOI:10.1080/10584580008215638

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The use of IrOxfor electrodes in PbZrxTi1−xO3(PZT) capacitors for ferroelectric memory applications has proven to be advantageous in several respects. In comparison with Pt, IrOxoften exhibits improved fatigue and provides resistance to hydrogen induced degradation at elevated temperatures. Since IrOxis often produced by sputtering in an oxygen containing environment, several forms of IrOxcan be produced depending on the process conditions. This work concentrates on an analysis of the DC reactive sputtering of IrOxfrom an Ir metal target. As with other oxidizable metals, Ir exhibits a transition between metal and oxide mode sputtering when sputtered in oxygen containing atmospheres. Variations in the Ar/O2gas flow ratio were used to produce Ir and IrOxfilms on both sides of the metal-to-oxide mode reactive sputtering transition. Changes in the IrOxfilm properties were quantified by using a combination of metrics including X-ray diffraction, sheet resistance, and stress. It was found that the, IrOxcrystalline structure and other IrOxproperties could be directly related to the ferroelectric switching performance of PZT capacitors with IrOxtop electrodes. A relationship between IrOxdeposition processes and resistance to etch induced damage of the ferroelectric properties was also observed.

ISSN:1058-4587    

DOI:10.1080/10584580008215639

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Ex-situgrown thin films of SrBi2Nb2O9(SBN) were deposited on platinum substrates using laser ablation technique. A low substrate-temperature-processing route was chosen to avoid any diffusion of bismuth into the Pt electrode. It was observed that the as grown films showed an oriented growth along the ′c′-axis (with zero spontaneous polarization). The as grown films were subsequently annealed to enhance crystallization. Upon annealing, these films transformed into a polycrystalline structure, and exhibited excellent ferroelectric properties. The switching was made to be possible by lowering the thickness without losing the electrically insulating behavior of the films. The hysteresis results showed an excellent square-shaped loop with results (Pr= 4 uC/cm2; Ec= 90 kV/cm) in good agreement with the earlier reports. The films also exhibited a dielectric constant of 190 and a dissipation factor of 0.02, which showed dispersion at low frequencies. The frequency dispersion was found to obey Jonscher's universal power law relation, and was attributed to the ionic charge hopping process according to earlier reports. The dc transport studies indicated an ohmic behavior in the low voltage region, while higher voltages induced a bulk space charge and resulted in non-linear current-voltage dependence.

ISSN:1058-4587    

DOI:10.1080/10584580008215640

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The PLZT (3/66/34), PLZT (3/46/54), PLZT (9/65/35) and PLZT (28/0/100) thin films were deposited on MgO (100), Sapphire (0001) and fused silica substrates by using pulsed KrF excimer laser deposition technique. The conventionalin-situand 2-step heating processes were utilized to facilitate the synthesis of a large area of uniform PLZT thin film. Pure perovskite phase can be obtained only under very narrow process conditions, the highly textured PLZT films can be easily obtained byin-situheating process. For PLZT (28/0/100) material, epitaxial films were successfully coated on MgO (100) substrates by 600°Cin-situand RTA 650°C 2-step heating processes. The latter was found to possess higher refractive index and lower extinction coefficient.

ISSN:1058-4587    

DOI:10.1080/10584580008215641

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Thin films of the composition (Pb1−xLax)TiO3, PLT, with x=0.05, 0.10 and 0.15 were sequentially pulsed laser deposited on Pt(Si) substrates at 200°C, followed by post-annealing at 550–600°C in furnace to result in a film with graded composition. The ferroelectric properties of the graded materials are markedly different from those of the uniform thin PLT films. For down graded materials, which contain PLT5 composition (x=0.05) at the top and PLT 15 composition (x=0.15) at the bottom of the films, the hysteresis loops are slim and the width of the P-E curves increases with voltage cycling, attaining an equilibrium polarization states similar to the P-E properties of PLT 15 thin films. By contrast, the ferroelectric hysteresis properties reaches the same value as those of PLT5 thin films when the composition is up-graded.

ISSN:1058-4587    

DOI:10.1080/10584580008215642

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The effects of sputtering conditions on the SrBi2Ta2O9films deposited via a single-target RF-sputtering process were investigated in this study. It was found that the composition of targets significantly affected the phases and the composition of the deposited films. When the target contained high bismuth content, SrBi2Ta2O9and a secondary Bi2O3phase were formed. When the bismuth content in the targets was insufficient, a pyrochlore phase was produced. SEM images revealed that the composition of the targets also affected the surface morphology of the obtained films. When the target-to-substrate distance was increased, bismuth oxide was formed, which resulted in an increase in the leakage current. By optimizing the deposition conditions, the ferroelectric properties of SrBi2Ta2O9films were improved.

ISSN:1058-4587    

DOI:10.1080/10584580008215643

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

MgTiO3thin films have been grown on various substrates by pulsed laser deposition (PLD) to investigate the application for microwave dielectrics and optical devices. Highly oriented MgTiO3thin films were obtained on sapphire (c-plane Al2O3). MgTiO3thin films deposited on SiO2/Si and platinized silicon (Pt/Ti/SiO2/Si) substrates were polycrystalline nature. MgTiO3thin films grown on sapphire were transparent in the visible and had a sharp absorption edge at 280 nm. These MgTiO3thin films had extremely fine feature of surface morphology, i.e., rms roughness of 0.87 nm. Dielectric constant and loss of MgTiO3thin films deposited by PLD were about 24 and 1.5% at 1MHz, respectively. These MgTiO3thin films also exhibited little dielectric dispersion.

ISSN:1058-4587    

DOI:10.1080/10584580008215644

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor