摘要:

The effects of bottom electrode annealing temperature on ferroelectric capacitors are examined. Temperatures between 350 and 600°C were used to anneal 2000 Å RuO0.8/500 Å Ti electrodes deposited by ion beam sputtering. Anneals were performed in flowing O2, N2, ultra high purity (UHP) Ar, and air. Scanning Electron Microscope (SEM) data show that between 500 and 600°C, in air and flowing O2, rectangular crystallites change to square crystallites. Energy Dispersive Spectroscopy (EDS) analysis shows that the square crystallites on the bottom electrodes annealed at 600°C in flowing O2have a higher oxygen content than the surrounding matrix. Atomic Force Microscopy (AFM) data show that the bottom electrodes annealed in air and flowing O2are rougher (root mean square (RMS) roughness between 50 and 80 nm) compared to the bottom electrodes that are unannealed (RMS roughness of 0.151 nm) and the bottom electrode annealed in flowing N2(RMS roughness of 3.8 nm). SEM data show that the 600°C bottom electrode anneal in UHP Ar resulted in a rougher surface, providing more nucleation sites for the PZT perovskite rosettes compared to the 400°C bottom electrode anneal with all other experimental parameters equal.

ISSN:1058-4587    

DOI:10.1080/10584589508012288

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

At the surface of poled ferroelectric (FE) material high electric fields are able to attract or repel charged toner particles. This property can be used for high speed printing applications. A simplified model of free FE surfaces (without electrodes) shows that screening charges are responsible for short range but intensive fields above the surface. Material properties and contrast enhancement for FE-printing are discussed.

ISSN:1058-4587    

DOI:10.1080/10584589508012289

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A ferroelectric-superconducting three-terminal device consisting of a YBa2Cu3O7-x(YBCO) base layer and a PbZrTiO3(PZT) gate has been fabricated which acts as a ferroelectric-superconducting field effect transistor (FSuFET). The PZT /YBCO layers were deposited sequentially on an MgO (100) substrate by excimer laser deposition. The thickness of the YBCO layer was nominally 100nm and that of the PZT layer was 500nm. Both conventional DC measurements and a modified admittance spectroscopy method were used to characterize the device. The YBCO channel resistance has been shown to be modulated by over 25% dependent on the polarization of the PZT gate, the highest modulation shown to date. The polarization state and thus the channel state were retained for greater than 106seconds. This was the first demonstration of non-volatility in such a superconducting logic device. The transient behavior of the ferroelectric-superconducting device has also been studied and shows four-state characteristics. The four states can be controlled by changing the PZT polarization state or switching of the YBCO channel from the superconducting state to the normal state.

ISSN:1058-4587    

DOI:10.1080/10584589508012290

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We present a method for calculating the dielectric constant and the dissipation factor for thin-film ferroelectric capacitors from scattering parameter measurements at multi-gigahertz frequencies. Physical measurement is discussed along with description of the model upon which the calculation is based. Experimental results for 0.5 micron films of PZT are reported up to 15 GHz. Direct measurement is compared with indirectly calculated values at the 100 MHz to 1.5 GHz range, showing excellent agreement.

ISSN:1058-4587    

DOI:10.1080/10584589508012291

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polycrystalline and epitaxial Ba0.5Sr0.5TiO3thin films were grown on Si by 90° off-axis sputtering for potential charge storage applications. Polycrystalline BST films deposited on Pt/Ta coated Si have demonstrated a dielectric constant as high as 600, and a loss tangent as low as 0.01 under optimized growth conditions. Epitaxial Ba0.5Sr0.5TiO3(110) was achieved by depositions on metallic SrRuO3(110) electrode, which was epitaxially grown on YSZ (100) buffered Si. The epitaxial heterostructure showed a high degree of crystallinity with little interdiffusion near the interfaces. The measured dielectric constant is about 360, and the leakage current density is lower than 4x10−7A/cm2at 1 V. A strong frequency dependence on dielectric constant and loss tangent is observed in 1–10 MHz frequency range for both types of film. This is attributed to the effect of a series resistance in the measurement loop. We show that roll-off frequency depends on both the magnitude of the capacitance and the resistivity of the bottom electrode.

ISSN:1058-4587    

DOI:10.1080/10584589508012292

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We evaluated depolarization characteristics of ferroelectric sol-gel Pb(Zr0.4Ti0.6)O3and MOD (Metallo-Organic-Decomposition) Bi-layered SrBi2Ta2O9thin-film capacitors derived by spin-on techniques with Pt electrodes. The evaluations were carried out for the extended experimental conditions, e. g., pulse height, pulse width, temperature, excess lead. Consequently, we found that the depolarization characteristics depended strongly on the capacitance of load capacitor. The newly obtained hysteresis loop during the pulse response indicates that sufficient field with opposite direction was generated on the ferroelectric capacitor at the moment the read pulse becomes zero. We experimentally found that the mechanism of depolarization is based on depoling (or partial switching) by an opposite-direction field arisen from accumulated switching charge on a load capacitor. This mechanism can be easily extended to the internal depolarization field due to the interfacial linear capacitor between the ferroelectric region and electrode.

ISSN:1058-4587    

DOI:10.1080/10584589508012293

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:1058-4587    

DOI:10.1080/10584589508012257

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor