• Title, Summary, Keyword: Ferroelectric

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Investigations of Ferroelectric Polarization Switching in Potassium Nitrate Composite Films

  • Kumar, Neeraj;Nath, Rabinder
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.2
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    • pp.60-65
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    • 2014
  • This article explains the experimental results of ferroelectric polarization switching (FPS) of potassium nitrate ($KNO_3$) with different polymers such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) using simple melt-press techniques. To analyze the ferroelectric polarization switching in potassium nitrate ($KNO_3$) composite films at room temperature, we applied the Ishibashi and Takagi theory (based on Avrami model) to the switching current transient. To investigate the dimensionality of domain growth, the ferroelectric polarization switching current (FPS current) was observed from the square - wave bipolar signals across a resistance of $0.1k{\Omega}$ in series with the composite films. The existence of a switching current transient pulse confirmed the ferroelectricity and indicated the stability of the ferroelectric phase (phase III) of $KNO_3$ at room temperature. Polarization hysteresis (P-E) characteristics supported the prominent features of ferroelectric polarization switching in the composite films at room temperature.

Surface Discharge Characteristics of a DC Corona Charged Ferroelectric Pellet Barrier (직류 코로나 하전된 강유전체구 층의 연면방전특성)

  • Geum, Sang-Taek;Lee, Geun-Taek;Mun, Jae-Deok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.5
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    • pp.385-390
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    • 1999
  • Surface corona discharge characteristics of a dc corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charges stored on the surfaces of the ferroelectric pellets by a dc corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between corona tip and mesh electrode. Positive and negative dc voltages were applied to the tip to generate partial discharges, and corona currents were estimated to investigate the buildup charge on ferroelectric pellets as a function of the applied time and the charge relaxation time constants of ferroelectric pellets. As a result, in the case of the negative corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be fenerated efficiently. It is also found that, charge relaxation time, dielectric constants offerroelectric pellets, polarity of applied voltage and applied time affected to the surface discharges among the ferroelectric pellets.

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A New Type of Nonthermal Plasma Reactor

  • Geum, Sang-Taek;Moon, Jae-Duk;Jun, Sun-Gon
    • The Korean Journal of Ceramics
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    • v.5 no.3
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    • pp.245-249
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    • 1999
  • A new type of nonthermal plasma reactor utilizing ferroelectric pellets is proposed to generate nonthermal plasma efficiently, which is used for simultaneous control of various pollutant gases. Electric charges stored on ferroelctric pellets by corona discharge between a corona tip and a mesh electrode provide partial electrical discharges among ferroelectric pellets. These partial electrical discharges can enhance partial discharges around the surface of ferroelectric pellets. This method utilizes wide reacting area of ferroelectric pellets and partial discharge. Positive and negative dc voltage are applied to the corona tip to generate partial discharges, and corona currents are estimated to investigate charge storage on ferroelectric pellets as function of time and charge relaxation time constants of ferroelectric pellects. As a result, charge relaxationtime, dielectric constants of ferroelectric pellets, polarity of applied voltage and applied time influence partial discharges among ferroelectric pellect.

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Recent Development in Polymer Ferroelectric Field Effect Transistor Memory

  • Park, Youn-Jung;Jeong, Hee-June;Chang, Ji-Youn;Kang, Seok-Ju;Park, Cheol-Min
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.8 no.1
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    • pp.51-65
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    • 2008
  • The article presents the recent research development in polymer ferroelectric non-volatile memory. A brief overview is given of the history of ferroelectric memory and device architectures based on inorganic ferroelectric materials. Particular emphasis is made on device elements such as metal/ferroelectric/metal type capacitor, metal-ferroelectric-insulator-semiconductor (MFIS) and ferroelectric field effect transistor (FeFET) with ferroelectric poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (TrFE). In addition, various material and process issues for realization of polymer ferroelectric non-volatile memory are discussed, including the control of crystal polymorphs, film thickness, crystallization and crystal orientation and the unconventional patterning techniques.

Nonvolatile Semiconductor Memories Using BT-Based Ferroelectric Films

  • Yang, Bee-Lyong;Hong, Suk-Kyoung
    • Journal of the Korean Ceramic Society
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    • v.41 no.4
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    • pp.273-276
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    • 2004
  • Report ferroelectric memories based on 0.35$\mu\textrm{m}$ CMOS technology ensuring ten-year retention and imprint at 175$^{\circ}C$. This excellent reliability resulted from newly developed BT-based ferroelectric films with superior reliability performance at high temperatures, and also resulted from robust integration schemes free from ferroelectric degradation due to process impurities such as moisture and hydrogen. The superior reliabilities at high temperature of ferroelectric memories using BT-based films are due to the random orientation by special bake treatments.

Corona Discharge and Ozone Generation Characteristics of a Wire-to-Wire Gap with a Ferroelectric Pellet Bed (강유전체 충진 선대선 방전갭의 코로나 방전 및 오존 발생특성)

  • Shin, Jung-Min;Bae, Chang-Hwan;Ahn, Chang-Jin;Lee, Jong-Hoon;Moon, Jae-Duk
    • Proceedings of the KIEE Conference
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    • pp.1873-1875
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    • 2003
  • Surface corona discharge characteristics of a ac corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charged stored on the surfaces of the ferroelectric pellets by a at corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between wire electrodes. As a result, in the case of the corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be generated efficiently. It is also found that, the ferroelectric pellet barrier discharge reactor had better discharge characteristics for plasma generation than the wire-to-wire discharge reactor without pellets.

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Current Status and Prospects of FET-type Ferroelectric Memories

  • Ishiwara, Hiroshi
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.1 no.1
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    • pp.1-14
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    • 2001
  • Current status and prospects of FET-type FeRAMs (ferroelectric random access memories) are reviewed. First, it is described that the most important issue for realizing FET-type FeRAMs is to improve the data retention characteristics of ferroelectric-gate FETs. Then, necessary conditions to prolong the retention time are discussed from viewpoints of materials, device structure, and circuit configuration. Finally, recent experimental results related to the FET-type memories are introduced, which include optimization of a buffer layer that is inserted between the ferroelectric film and a Si substrate, development of a new ferroelectric film with a small remnant polarization value, proposal and fabrication of a 1T2C-type memory cell with good retention characteristics, and so on.

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Feasibility of ferroelectric materials as a blocking layer in charge trap flash (CTF) memory

  • Zhang, Yong-Jie;An, Ho-Myoung;Kim, Hee-Dong;Nam, Ki-Hyun;Seo, Yu-Jeong;Kim, Tae-Geun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.119-119
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    • 2008
  • The electrical characteristics of Metal-Ferroelectric-Nitride-Oxide-Silicon (MFNOS) structure is studied and compared to the conventional Silicon-Oixde-Nitride-Oxide-Silicon (SONOS) capacitor. The ferroelectric blocking layer is SrBiNbO (SBN with Sr/Bi ratio 1-x/2+x) with the thickness of 200 nm and is fabricated by the RF sputter. The memory windows of MFNOS and SONOS capacitors with sweep voltage from +10 V to -10 V are 6.9 V and 5.9 V, respectively. The effect of ferroelectric blocking layer and charge trapping on the memory window was discussed. The retention of MFNOS capacitor also shows the 10-years and longer retention time than that of the SONOS capacitor. The better retention properties of the MFNOS capacitor may be attributed to the charge holding effect by the polarization of ferroelectric layer.

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Nanoscale Probing of Ferroelectric Domain Switching Using Piezoresponse Force Microscopy

  • Yang, Sang Mo;Kim, Yunseok
    • Journal of the Korean Ceramic Society
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    • v.56 no.4
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    • pp.340-349
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    • 2019
  • In ferroelectric materials, piezoresponse force microscopy (PFM) has been widely used to explore ferroelectric domain switching. In this article, we review the fundamentals of nanoscale probing of ferroelectric domain switching using PFM, including the basic principles of PFM and a variety of PFM studies on local domain switching. We also introduce advanced PFM techniques for exploring switching behavior. Finally, we discuss several issues and perspectives in nanoscale probing of ferroelectric domain switching using PFM. PFM has played an important role in exploring switching behavior in ferroelectric materials, and it could be further developed to probe more detailed switching information.

EXISTENCE OF PERIODIC SOLUTIONS IN FERROELECTRIC LIQUID CRYSTALS

  • Park, Jinhae
    • Journal of the Chungcheong Mathematical Society
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    • v.23 no.3
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    • pp.571-588
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    • 2010
  • We introduce the Landau-de Gennes model in order to understand molecular structures in ferroelectric liquid crystals. We investigate equilibrium configurations of the governing energy functional by means of bifurcation analysis. In particular, we obtain periodic solutions of the functional, which is a signature of a rich variety of applications of ferroelectric materials.