摘要:

Metal-ferroelectric-semiconductor field-effect-transistor (MFSFET) arrays were fabricated using Al/BaMgF4/Si(111) structures, for the first time, and their electrical properties were investigated. An MFSFET array composed of Si stripes with drain/source regions and 9 gate electrodes was fabricated on an n-type Si(111) substrate. It was found that IDS-VGScharacteristic of the fabricated MFSFETs showed a hysteresis loop due to spontaneous polarization of BaMgF4. To demonstrate the memory effect more clearly, IDS-VDScharacteristics after applying pulse voltage to the gate terminal of the FET were measured, in which ON-OFF ratio of drain saturation current was 4×102at zero gate voltage.

ISSN:1058-4587    

DOI:10.1080/10584589908228450

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The Metal-Ferroelectric-Insulator-Semiconductor FET structure (or MFISFET) has been studied as a non-volatile memory device1-4ever since the IEEE publication by Wu4in 1974. However, so far there has not been any commercial product, because of some severe problems, including interface problems and retention time problem, among others.

ISSN:1058-4587    

DOI:10.1080/10584589908228451

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ferroelectric gate MOS capacitors using the “Y-1” family of ferroelectric materials were evaluated. The capacitors were formed by connecting the ferroelectric capacitor and the MIS capacitor in series. The experimental results show the dependence of the memory window on the ferroelectric/insulator capacitance ratios, which gives some useful information on the design of MFSFETs.

ISSN:1058-4587    

DOI:10.1080/10584589908228452

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Metal Ferroelectric Insulator Semiconductor Fieid Effect Transistors (MFISFET) were fabricated using CMOS process. The PZT/TiO2combined layer was used as a gate dielectric layer of MFISFET device. The memory window of p type MFISFET was about 2.5 V. The threshold voltages of p-MFISFET and n-MFISFET are −1.8 V and 3.8 V, respectively. The Id-Vd characteristic shows a nonvolatile memory function through write and read operation. The retention property of p-MFISFET is examined by reading drain currents after writing to gate. About 15% reduction in the drain current is observed when it is read after 100 minutes.

ISSN:1058-4587    

DOI:10.1080/10584589908228453

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Recently, we have grown epitaxial BaTiO3films directly on a Si (001) substrate using molecular beam epitaxy (MBE). The films have been characterized both physically (RHEED, XRD, AFM, SE) and electrically (CV & IV). The films show streaky RHEED patterns and sharp X-ray diffraction patterns, indicating epitaxial BTO growth. The leakage current is below 1E-8 A/cm2 at 2V. The CV results show good interface properties. The films exhibit a 0.5V hysteresis in the CV curves.

ISSN:1058-4587    

DOI:10.1080/10584589908228454

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ideal ferroelectrics have mostly been modeled as insulators, i.e., infinite band gap materials, having a spontaneous polarization. Based on this assumption, theories for the finite size effect, the domain configuration, and the depolarization field instability have been proposed. However, most of oxide perovskite ferroelectrics have finite band gaps of 3 to 4 eV. We show that the inclusion of the finite band gap effect changes drastically conventional understanding of the finite size effect and others. The conclusions extracted from the present approach are consistent with recent experimental results. In particular, we discuss the stability of ferroelectric memory devices in detail.

ISSN:1058-4587    

DOI:10.1080/10584589908228455

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Bismuth layered-perovskite thin films of SrBi2Ta2O9(SBT) solid solution were prepared by chemical solution deposition method. In order to form the robust SBT thin films, preannealing methods such as rapid thermal annealing (RTA) and furnace annealing were studied in terms of physical and electrical properties of SBT thin films. SBT thin films preannealed by furnace exhibited better surface morphology and electrical properties than those preannealed by RTA. The crystallization mechanism of SBT thin films by heat treatment was examined by using X-ray diffraction (XRD) analysis and scanning electron micrograph (SEM). For the robust SBT thin films with (P*-P⁁) value of about 20 uC/cm2, leakage current density of less than 10−7A/cm2, and breakdown voltage of 15 V, the optimal condition of furnace preannealing was found to be 700 °C for 30 min.

ISSN:1058-4587    

DOI:10.1080/10584589908228456

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

SrBi2Ta2O9based Ferroelectric FETs with a CeO2buffer layer deposited by Metal Organic Decomposition (MOD) were fabricated on p-Si (100) substrate and analyzed in detail. The hysterisis curve (drain current vs. gate voltage) of the FET shows the counter-clockwise direction, which demonstrates the change of channel conductivity due to the ferroelectric polarization. The memory window with the gate voltage of ±10V was 2V. The difference of current ratio of Ids(on)to Ids(off)was 5∼7 orders in magnitude which is easily sensed by sense amplifiers. The charges of “on” state stored decay logarithmically with time without severe initial loss of data. This indicates the FET-FeRAM can be implemented in NDRO applications.

ISSN:1058-4587    

DOI:10.1080/10584589908228457

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ferroelectric films grown on Si substrates using Y2O3buffer layers were investigated by cross-sectional high-resolution transmission electron microscopy (HRTEM). It was found that no interfacial SiO2layer was formed when an Y2O3layer was grown by molecular beam epitaxy (MBE) on a Si(111) substrate at 600°C, while that a SiO2layer was formed on a Si(100) substrate under the same growth conditions. Then, ferroelectric YMnO3, SrBi2Ta2O9(SBT), and Pb(Zr,Ti)O3(PZT) films were deposited on the Y2O3/Si structures and cross-sections were observed. It was found that the interfacial SiO2layer about 5 to 6 nm in the thickness was formed even on a Si(111) substrate after deposition of the ferroelectric film. It was also found that polygrains in PZT film were much smaller than those in SBT, although both films were formed by the same sol-gel driven method.

ISSN:1058-4587    

DOI:10.1080/10584589908228458

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ferroelectric channel in a Metal-Ferroelectric-Semiconductor Field Effect Transistor (MFSFET) can partially change its polarization when the gate voltage nears the polarization threshold voltage as shown by Aizawa[1]. This causes the MFSFET Drain current to change with repeated pulses of the same gate voltage near the polarization threshold voltage. A previously developed model [2] assumed that for a given gate voltage and channel polarization, a single Drain current value would be generated. The earlier model accurately predicts the Drain current given a series of increasing and decreasing pulses, but does not predict the current well for a series of random pulses. A study has been done to characterize the effects of partial polarization on the Drain current of a MFSFET. These effects have been incorporated into a more comprehensive mathematical model of the MFSFET. The model takes into account the hysteresis nature of the MFSFET and the time dependent decay as well as the effects of partial polarization.

ISSN:1058-4587    

DOI:10.1080/10584589908228459

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor