摘要:

A two-step pulsed laser deposition process has been successfully applied for growing the (PbxLa1−x)(ZryTi1−y) O3, PLZT, thin films. These films exhibit good ferroelectric characteristics (Pr=18 μC/cm2;Ec=80 kV/cm;JL≤0.2 μA/cm2), whenever crystalline SrRuO3materials were used as buffer layers. However, the electrical properties of PLZT films were markedly degraded whenever the amorphous SrRuO3or (La0.5Sr0.5)CoO3layer was used as buffer layer.

ISSN:1058-4587    

DOI:10.1080/10584589908215604

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

(PbLa)(Zr,Ti)O3(PLZT) thin films were fabricated by RF magnetron sputtering. Aiming at process development for FRAM® production, PLZT films were deposited on 6-inch substrates using a 12-inch ceramic target. High deposition rate was realized at relatively low sputtering power by utilizing a high-density PLZT target. Precise compositional control was achieved by controlling sputtering condition. A non-stop 1000-wafer deposition was performed showing high process stability in terms of both deposition rate and ferroelectric properties.

ISSN:1058-4587    

DOI:10.1080/10584589908215605

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Thin films of bismuth-layer-structured perovskites such as SrBi2Ta2O9(SBT) and BaBi4Ti4O15(BBiT) with preferred orientations have been grown by pulsed laser deposition (PLD) on epitaxial conducting LaNiO3(LNO) electrodes on single crystalline (100) SrTiO3(STO) or on top of epitaxial buffer layers on (100) silicon. X-ray diffraction (XRD) analysis and cross-section electron microscopy reveal that the films consist of c-axis oriented regions and mixed a-axis and c-axis oriented regions. The regions with mixed a-axis and c-axis orientation show high surface roughness due to the rectangular crystallites protruding out of the surface, whereas the c-axis oriented regions show a smooth surface morphology. In the mixed a-axis and c-axis oriented regions, the SBT and BBiT films exhibit saturated ferroelectric hysteresis loops with a remnant polarization Prof about 2 μC/cm2and coercive fields Ecof about 20 kV/cm for SBT and 60 kV/cm for BBiT. No polarization fatigue was observed up to 108cycles neither for SBT nor for BBiT films. The regions having c-axis orientation with a smooth surface morphology in contrast exhibit a linear P-E curve. The results show that the ferroelectric properties of a planar capacitor consisting of ferroelectric Bi-layer-structured perovskites depend on the crystalline orientation of the film.

ISSN:1058-4587    

DOI:10.1080/10584589908215606

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Thin films of Bi based layered-structure solid solution, SrBi2Ta2O9-SrBi2Nb2O9(SBTN), were prepared by conventional single target RF-magnetron sputtering on Pt/Ti/SiO2/Si substrates with a diameter of 6 inches. The capacitors were fabricated by patterning the top Pt electrode using photolithography. SBTN thin films with random and c-axis preferred orientation were obtained using RTP annealing and conventional furnace annealing, respectively. The electrical properties were characterized by both the hysteresis and pulsed field methods. A 2Pr of 24 μC/cm2and Ecof 125kV/cm were measured from randomly oriented 1600Å films. The films exhibit excellent fatigue performance.

ISSN:1058-4587    

DOI:10.1080/10584589908215607

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A heterostructure of (001)PZT(53/47)/(110)SrRuO3(SRO) was deposited on a miscut (001)SrTiO3(ST) substrate by a magnetron sputtering. The film thickness of the PZT and SRO ranged from 100nm to 200nm. The miscut angles were typically 1.7°. The heterostructure was grown on the miscut ST substrates under a step-flow growth. The heterostructure was tightly bonded to the ST substrate without an interfacial layer. The sputtered PZT thin films were tetragonally deformed with c=4.16 Å (bulk c-lattice parameter, 4.14 Å). A room temperature dielectric constant of the PZT thin films was 200 to 300 at 1kHz. The P/E hysteresis measurements indicated that the saturation polarization Pswas 40 μ C/cm2with a coercive field Ecof 400 kV/cm to 500 kV/cm. The Ecobserved was one order of magnitude higher than a bulk value for PZT. The high values of Ecwere observed in a perfect c-domain orientation without an interfacial layer or 90° domains.

ISSN:1058-4587    

DOI:10.1080/10584589908215608

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Thin films of Ca and Sr doped PLZT(3/40/60) were RF sputtered on 6-inch substrates using ULVAC CERAUS ZX-1000 magnetron sputtering system. The 2000 Å PLZT films showed good thickness uniformity across the wafer (less than ± 1.5%). The crystallized PLZT films are highly {111} textured. The 3V QSWis above 30 μC/cm2and V90%is below 3.5V. After 109fatigue cycles, 3V Qswis still 29 μC/cm2. The films also showed good retention properties. 3V Qss(10year) = 12 μC/cm2, 3V QOS(10year) = 9 μC/cm2. The same process was utilized to run 1000 wafers on ZX-1000. The stable ferroelectric performance achieved during 100 kWh sputtering indicates good repeatability of the ZX-1000 mass production tool.

ISSN:1058-4587    

DOI:10.1080/10584589908215609

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The preparation and ferroelectric properties of layered ferroelectric barium-doped SrBi2Ta2O9were investigated in this study. Pure layered perovskites were successfully synthesized when the mixed reactants were heated up to 900°C. The formation of solid solutions of barium-doped SrBi2Ta2O9were confirmed. The addition of barium cations was found to substantially improve the sinterability of SrBi2Ta2O9, and resulted in densified specimens at low sintering temperatures. The degree of c-axis preferred orientation of the sintered specimens also increased with the increase in the barium content in SrBi2Ta2O9. This variation in the c-axis orientation was related to the morphological change of the grains in barium-doped SrBi2Ta2O9. The barium-doped specimens exhibited well saturated P-E loops and high remanent polarization.

ISSN:1058-4587    

DOI:10.1080/10584589908215610

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The influence of the addition of bismuth oxide on the sintering behavior and ferroelectric properties of SrBi2Ta2O9(SBT) ceramics has been investigated in this study. Doping excess Bi2O3in SBT greatly enhances the densification process and changes the morphology of grains from round to plate-like shape. With the addition of Bi2O3, densified SBT is obtained after 1000°C-sintering, and its degree of c-axis orientation increases with raising the sintering temperature. The increase in the density of SBT significantly results in the increase in both of its dielectric constant and remanent polarization. However, the occurrence of preferred c-axis orientation in SBT tends to reduce its remanent polarization.

ISSN:1058-4587    

DOI:10.1080/10584589908215611

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Fatigue free ferroelectric Pb5Ge3O11(PGO) films have been prepared using metalorganic chemical vapor deposition (MOCVD). [Pb(thd)2] and [Ge(OC2H5)4] were used as the precursors for lead and germanium, respectively. The PGO films were deposited onto Ir/Ti/SiO2/Si and Pt/Ti/SiO2/Si wafers to measure their compositions, phase formation, microstructures and ferroelectric properties. The X-ray pattern showed the formation of C-axis oriented PGO films. All the PGO films showed excellent fatigue characteristics: no fatigue was observed up to 1 × 109switching cycles. It is believed that the superior fatigue properties of these PGO films are due to the PGO lattice structure. PGO materials have large polarization along the c axis, but little or no polarization along a and b axis, thus the domain configuration is 180°. This is one reason that PGO has excellent fatigue properties, which is similar to Bi-layered oxides such as SrBi2Ta2O9material. A typical 300-nm thick PGO film exhibited a saturated and square hysteresis loop. The remanent polarization (2Pr) and coercive field (2Ec) values at 5V were about 3.72 μC/cm2and 67 kV/cm, respectively. The leakage current increased with increasing applied voltage, and is about 9.5 × 10−7A/cm2at 100 kV/cm. The maximum dielectric constant is about 35. The MOCVD PGO films can be used for single transistor memory applications.

ISSN:1058-4587    

DOI:10.1080/10584589908215612

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

MOCVD is an attractive technique for the deposition of ferroelectric thin films. In order to exploit the full potential of the technique, the properties of the metalorganic precursor sometimes need to be tailored in order to optimise process parameters. In this paper we describe how the substitution of simple alkoxide groups by β-diketonate or other chelating groups can lead to precursors with improved physical properties and optimised MOCVD performance.

ISSN:1058-4587    

DOI:10.1080/10584589908215613

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor