摘要:

Recent reports on the current-voltage (I-V) characteristics of SrTiO3and (Ba,Sr)TiO3thin film capacitors with Pt electrode suggest that their leakage properties are controlled by Schottky emission from cathode. However, their dynamic permittivities obtained from the Schottky plot are always much smaller than those expected from optical measurements. The most plausible approach to explain this disagreement is to incorporate the effect of electric field enhancement due to interfacial roughness into the Schottky emission model. Electric field at the interface, for the first order approximation, can be given by [(r+t)/r](V/t), where r, t and V respectively denote radius of curvature representing interfacial roughness, dielectric thickness and applied voltage. This model predicts that I-V characteristics are the functions of r and V for the ultimate case of r ≪ t. We have closely studied the I-V characteristics of sputter-deposited SrTiO3films and have obtained the results which strongly support our prediction.

ISSN:1058-4587    

DOI:10.1080/10584589508013584

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

High dielectric constant material Ba0·6Sr0·4TiO3(BST) was heteroepitaxially grown over YBa2Cu3O7-x(YBCO) on Lanthanum aluminate (LaAlO3) substrates. The electrical characteristics of the BST film was studied by depositing electron beam evaporated platinum (Pt). The capacitancevoltage (C-V) measurements at various temperatures up to 100°C show negative temperature coefficient for capacitance, confirming the paraelectric phase. The capacitance vs voltage and current vs voltage characteristics show asymmetry with the polarity of the applied voltage. The asymmetry in the capacitance and current-voltage characteristics can be explained by defect chemistry model of electrode/oxide interface.

ISSN:1058-4587    

DOI:10.1080/10584589508013585

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

La-modified lead titanate(PLT) thin films were prepared on Pt/SiO2/Si substrate by hot-wall type low pressure-metalorganic chemical vapor deposition(LP-MOCVD). The films were deposited at 500°C under the low pressure of 1000mTorr. The films were annealed at 650°C for 10min with O2ambient before top-Pt electroding. Schottky emission was observed for Pt/PLT(12)/Pt capacitor. With increasing La mole%, surface morphologies of the PLT films were improved smoothly and leakage current density decreased.

ISSN:1058-4587    

DOI:10.1080/10584589508013586

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This work investigates the feasibility of a 1T-1C memory cell consisting of an n-channel transistor and ferroelectric SrBi2Ta2O9as the capacitor dielectric. 1T-1C ferroelectric memory cells processed through interconnect metalization are discussed. Advantages and disadvantages of two different process sequences are examined. Data indicates that n-channel transistor damage is highly dependent on the process sequence, and that a SrBi2Ta2O91T-1C memory cell is fully functional through interconnect metalization.

ISSN:1058-4587    

DOI:10.1080/10584589508013587

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The development of ferroelectric memory device requires improvements in electrical characteristics such as fatigue, retention, imprint and other properties. Fatigue properties of PZT thin films were improved by using Pt/IrO2or Ir/IrO2used as electrodes, we reported. This report presents a study of the retention and the imprint characteristics of PZT thin films on various electrodes. Pt/IrO2and Ir/IrO2layer structures were used as electrodes of the PZT capacitors. In the case of using an Ir/IrO2electrode, the improvements in electrical properties from the measurements of the retention and the imprint characteristics.

ISSN:1058-4587    

DOI:10.1080/10584589508013588

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An infinite nondestructive read memory (NDRO) has been developed using a ferroelectric capacitor memory unit cell, the capacitance differential observed between a fully and partially polarized capacitor, a two transistor/two capacitor architecture and a modified latch sense amplifier.

ISSN:1058-4587    

DOI:10.1080/10584589508013589

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper reviews the current state of ferroelectric-based microactuators. The advantages of ferroelectric-based microactuation are considered. Several actuator concepts are discussed including unimorph-based cantilever actuators, membrane-based micropumps, linear positioning actuators using folded geometries of cascaded elementary actuators for both in-plane and out-of-plane displacements, linear stepper motors using inch-worm geometries, and ultrasonic-based micromotors. Optimistic, order-of-magnitude estimates of actuator performance are given based on simple, idealized analysis. Processing issues in fabricating ferroelectric-based microactuators are also considered.

ISSN:1058-4587    

DOI:10.1080/10584589508013590

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Investigations of sputtered strontium titanate films with typical thicknesses of 1 μm demonstrate that the electrical conductivity [sgrave] of these thin films exhibits a dependence on the oxygen partial pressure P(O2) that is typical for this material and is similar to that of polycrystalline bulk materials or single crystals. In order to determine the oxygen-sensitive properties of SrTiO3thin films, various oxygen partial pressures P(O2) can be set up in the environment of the gas-sensitive elements by means of different gas mixtures or by using oxygen pumps realized in the form of stabilized zirconium oxide ZrO2. Two different measurement principles can be used to test the kinetic behavior of sputtered SrTiO3films with respect to rapid changes in the oxygen partial pressure under laboratory conditions. One way of achieving rapid changes in the oxygen partial pressure is to change the gas composition quickly at constant pressure in a sample chamber by using injection valves of the kind used in motor vehicles. However, an alternative approach is to perform kinetic experiments with a constant gas composition while the total pressure changes.

ISSN:1058-4587    

DOI:10.1080/10584589508013591

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Deposition of LiNbO3thin films on R-cut (0112) sapphire by rf magnetron sputtering has been systematically investigated and repeatable epitaxial relationships between LiNbO3thin film and sapphire substrate were observed. As a result, the effect of sputtering parameters on deposition of LiNbO3thin films was determined. Optimal conditions for deposition of high quality (1120), (0112) and (1010) LiNbO3thin films were found. A filter was successfully fabricated by forming interdigital transducers (IDT) on the surface of a (1010) LiNbO3thin film on (0112) sapphire. The frequency response curve was measured, and the results are compared with a theoretical model.

ISSN:1058-4587    

DOI:10.1080/10584589508013592

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Piezoelectric membranes consisting of PbZrxTi1−xO3(PZT) films on silicon diaphragms have been fabricated, investigated, and applied for micromotors. The PZT films were deposited by sputtering and sol gel techniques. Resonance amplitudes of up to 1000 nm/V have been measured for 16 μm thick, 2 mm diameter membranes with 0·6 μm PZT. The PZT films show a preferred direction of polarization, which seems to depend on the deposition technique. Membranes of 4 mm diameter have been successfully applied as a vibrator of a micro motor, allowing for the first time the characterization of a PZT thin film micro motor. The motor could be operated with voltages as low as 1·0 Vrms, which is much less than has been obtained with ZnO micro motors and is sufficiently low for standard battery and IC supply voltages. A 100 h degradation test of frequency and amplitude has revealed a 5% drop in amplitude, possibly due to depolarization.

ISSN:1058-4587    

DOI:10.1080/10584589508013593

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor