• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2131-2134
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• 2015

In this study, It has been demonstrated a new and realizable possibility of the ferroelectric random access memory devices by all solution processing method with paper substrates. Organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin films were formed on paper substrate with Al electrode for the bottom gate structure using spin-coating technique. Then, they were subjected to annealing process for crystallization. The fabricated PVDF-TrFE thin films were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was found from polarization versus electric field (P-E) measurement that a PVDF-TrFE thin film on paper substrate showed very good ferroelectric property. This result agree well with that of a PVDF-TrFE thin film fabricated on the rigid Si substrate. It anticipated that these results will lead to the emergence of printable electron devices on paper. Furthermore, it could be fabricated by a solution processing method for ferroelectric random access memory device, which is reliable and very inexpensive, has a high density, and can be also fabricated easily.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.123-126
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• 2007

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.311-314
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• 2004

A new type of high frequency wideband ultrasonic transducer with a separation between a transmitter and a receiver was proposed and its characteristics were simulated using the PSpice model. The piezoelectric ceramic $PbTiO_{3}$ as a transmitter and the piezoelectric copolymer P(VDF-TrFE) as a receiver were used for high sensitivity and wide bandwidth, respectively. The characteristics of a center frequency approximately 40MHz focusing transducer fabricated in this study showed very wide bandwidth which could give an axial spatial resolution better than 30um in the B-mode image for biological tissues.

• Journal of Sensor Science and Technology
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• v.10 no.2
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• pp.86-90
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• 2001

A pyroelectric senior using P(VDF/TrFE) film for sensing materials has been fabricated and evaluated with other commercial pyroelectric sensors that use ceramic materials for sensing. The device was mounted in a TO-5 housing to detect infrared light of $5.5{\sim}14\;{\mu}m$ wavelength. The NEP (noise equivalent power) and specific detectivity $D^*$ of the device were $2.13{\times}10^{-8}\;W$ and $9.37{\times}10^6\;cm/w$ respectively under emission energy of $13\;{\mu}W/cm^2$ respectively. These result shows a better characteristics than other commercial pyroelectric sensors NEP $8.08{\times}10^{-7}\;W$ and $D^*$ $2.47{\times}10^5\;cm/w$.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.907-909
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• 2009

Low voltage operated top gated polymer transistors were fabricated with a high permittivity polymer, P(VDF-TrFE) and F8T2 as a gate dielectric and semiconducting layer, respectively. The operating voltage of transistors was effectively reduced under -10 V and typical threshold voltages were as low as -1 ~ -4 V with the reasonable charge carrier mobility of $10^{-3}cm^2$/Vs for the amorphous polymer. The large hysteresis in transfer curve was improved effectively by annealing at low temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.184-188
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• 2014

The electro-optic properties in Langmuir Blodgett films of poly (vinylidene fluoride trifluoroethylene) are investigated in the crossover region between two and three dimensions. The absence of finite size effect is observed in the films thinner than 20 nm, which confirms that these films are two dimensional ferroelectrics. The copolymer LB film of P(VDF-TrFE) exhibits the largest electro-optic response(26 pm/V) at 10 layer thickness. The cross-over behavior of electro-optic effect around the 10 layer thickness was discussed with the formation of nanomesa after thermal annealing.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.585-596
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• 2012

PVDF(poly vinylidene fluoride) and P(VDF-TrFE)(poly vinylidene fluoride-tetrafluoroethylene) are the typical piezoelectric polymers with unique properties. Even they are inferior to conventional piezoelectric ceramics PZT in electromechanical conversion efficiency and interior loss, though they are superior in receiving sensitivity and frequency bandwidth. Their acoustic impedances are relatively close to water or biological tissue and it is easier to make thin film than other piezoelectric materials. Futhermore, the film is so flexible that it is easy to attach on a complex surface. Those properties are suitable for the ultrasound transducers which are useful for medical and biological application, so that various types of polymer transducers have been developed. In this paper, several important considerations for design and fabrication of piezoelectric polymer transducers were described and their effect on the transducer performance were demonstrated through the KLM model analysis. Then, it was briefly reviewed about the structures of the polymer transducers developed for obtaining images as well as the characteristics of the images in several important medical and biological application fields.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.2041-2044
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• 2004

A pyroelectric sensor using $PbTiO_3$/P(VDF/TrFE) nanocomposites thin film for sensing materials has been fabricated and evaluated with other commercial pyroelectric sensors that use ceramic materials for sensing. The device was mounted in a TO-5 housing to detect infrared light of 5.5 ~ 14 ${\mu}m$ wavelength. The NEP (noise equivalent power) and specific detectivity D of the device were 1.30 ${\times}$ $10^{-8}$W and 1.53 ${\times}$ $10^7$cm /W respectively under emission energy of 13 ${\mu}$W/c$m^2$ respectively. This result shows a better characteristic than the other commercial pyroelectric infrared sensors.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.281.2-281.2
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• 2016

Two-dimensional van der Waals (2D vdWs) materials have been extensively studied for future electronics and materials sciences due to their unique properties. Among them, black phosphorous (BP) has shown infinite potential for various device applications because of its high mobility and direct narrow band gap (~0.3 eV). In this work, we demonstrate a few-nm thick BP-based nonvolatile memory devices with an well-known poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] ferroelectric polymer gate insulator. Our BP ferroelectric memory devices show the highest linear mobility value of $1159cm^2/Vs$ with a $10^3$ on/off current ratio in our knowledge. Moreover, we successfully fabricate the ferroelectric complementary metal-oxide-semiconductor (CMOS) memory inverter circuits, combined with an n-type $MoS_2$ nanosheet transistor. Our memory CMOS inverter circuits show clear memory properties with a high output voltage memory efficiency of 95%. We thus conclude that the results of our ferroelectric memory devices exhibit promising perspectives for the future of 2D nanoelectronics and material science. More and advanced details will be discussed in the meeting.