• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.881-884
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• 2008

In this study, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) in the composition from 51/49, was deposited on platinum for a metal-ferroelectric-metal structure. From XRD patterns, the 70 nm- and 140 nm-thick PVDF-TrFE films showed the intensity peak of near $20^{\circ}$ connected to a ferroelectric phase. Moreover, the thicker film indicated the higher intensity than thinner one. The difference of the remanent polarization (2Pr) at 0 V is decreased gradually from 10.19 to $5.7{\mu}C/cm^2$ as the thickness decrease from 140 to 70 nm. However, when the thickness decreased to 50 nm, the 2Pr rapidly drop to $1.6{\mu}C/cm^2$ so the minimum critical thickness might be at least 70 nm for device. Both different thickness films, 70 and 140 nm, indicated that the characteristic of current density-voltage was measured for $10^{-6}{\sim}10^{-7}A/cm^2$ below 15 V and the thicker film maintained relatively lower current density than thinner one. From these results, we can expect that the electrical properties for the devices particularly ferroelectric thin film transistor using PVDF-TrFE copolymer were able to be on the trade-off relationship between the remanent polarization with the bias voltage and the leakage current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.310-311
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• 2008

We have studied electro-optical characteristics of fringe-field switching (FFS) mode with high $d{\Delta}n$ according to the electrode position. In this device, the fringe-electric field drives the LCs to rotate so that the dielectric torque is electrode-positional dependent, which results in electrode-position dependency in the LC's rotating angle. We confirmed polarization microscope image and chromaticity diagram at the different electrode position with LC that have high $d{\Delta}n$. Since the FFS mode is influenced by horizontal and vertical electric field, the FFS mode modulates light using both phase retardation and polarization rotation effect, which had already been verified with previous studies. However, from another point of view, tight modulation of FFS mode has been demonstrated by performing experiment and calculated simulation at the high $d{\Delta}n$ LC cell.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.183-196
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• 2008

This research will mainly focus on security issues in a university campus and delve into the risk factors and its characteristics due to the extreme polarization growth, and ultimately conduct research on legislative issues regarding safety & security management. A university campus is a miniature of the society, concentrated with human resources, material resources and knowledge information resources. It is also a region in which various underlying risk factors threaten these resources. However, due to the insensibility of danger and carefree indolence, these risk factors have been ignoring, leaving university campus amidst a "dead zone." Currently, a systematic and synthetic measures not only for safety inside the laboratory but also for the new type of crimes such as cyber crimes and motiveless crime due to extreme polarization, stress, uneasiness about the future, increase of mental illnesses, and drug abuse are urgently required. Therefore, I would like to introduce a legislative program in a crisis management perspective that can prevent universities from danger and protect the resources which would ultimately create a new security system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.1
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• pp.6-10
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• 2001

In this study, we investigated the optical properties of sub-wavelength a-Si thin film transmission gratings, especially the polarization effect, the phase difference and the birefringence by using linearly polarized He-Ne laser beam (632.8nm). The a-Si transmission grating of the thickness $of < 0.1 \mum$ with four-type period($\Lambda = 0.4 \mum and 0.6 \mum$ for sub-wavelength and $\Lambda = 1.0 \mum and 1.4 \mum$ for above-wavelength) on quartz substrates have been fabricated using 50 KeV Ga+ Focused-Ion-Beam(FIB) Milling and $CF_4$Reactive-Ion-Etching(RIE) method. Finally, we obtained the trating array of a-Si thin film with a period $0.4 \mum, 0.6 \mum, 1.0 \mum, 1.4 \mum$ which have nearly equal finger spacing and width, sucessfully. Especially, for gratings with $\Lambda = 0.6 \mum(linewidth=0.25 \mum, linespace=0.35\mum), the \etamax at \theta_в=17.0^{\circ}$ is estimated to be 96%. As the results, we believe that the sub-wavelength grating arrayed a-Si thin film has the applicability as the optical device and components.

• Advances in nano research
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• v.13 no.2
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• pp.199-206
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• 2022

We present the high-brightness large-area 10.1" in-cell polarizer display panel integrated with a wire grid polarizer (WGP) and metal reflector, from the initial design to final system development in a commercially feasible level. We have modeled and developed the WGP architecture integrated with the metal reflector in a single in-cell layer, to achieve excellent polarization efficiency as well as brightness enhancement through the light recycling effect. After the optimization of key experimental parameters via Taguchi method, the roll nanoimprint lithography employing a flexible large-area tiled mold has been utilized to create the 90 nm-pitch polymer resist pattern with the 54.1 nm linewidth and 5.1 nm residual layer thickness. The 90 nm-pitch Al gratings with the 51.4 nm linewidth and 2150 Å height have been successfully fabricated after subsequent etch process, providing the in-cell WGPs with high optical performance in the entire visible light regime. Finally we have integrated the WGP in a commercial 10.1" display device and demonstrated its actual operation, exhibiting 1.24 times enhancement of brightness compared to a conventional film polarizer-based one, with the contrast ratio of 1,004:1. Polarization efficiency and transmittance of the developed WGPs in an in-cell polarizer panel achieve 99.995 % and 42.3 %, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.681-686
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• 2017

Degradation is commonly observed in field-aged PV modules due to corrosion of the photovoltaic ribbon. The reduced performance is caused by a loss of fill factor due to the high series resistance in the PV ribbon. This study aimed to mitigate the degradation by corrosion using five sacrificial anodes - Al, Zn and their alloys - to identify the most effective material to mitigate the corrosion of the PV ribbon. The corrosion behavior of the five sacrificial anode materials were examined by open circuit potential measurements, potentiodynamic polarization tests, and galvanic current density and potential measurements using a zero resistance ammeter. Immersion tests for 120 hours were also conducted using materials and damp heat test tests were performed for 1500 hours using 4 cell mini modules. The Al-3Mg and Al-3Zn-1Mg sacrificial anodes had a low corrosion rate and reduced drop in power, making then suitable for long-term use.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.159-159
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• 2010

We conducted bum-in test by current stress to evaluate acceleration reliability characteristics about p-resistivity influence of GaN-based light-emitting diodes. The LEDs used in this study are the polarization field-induced LED(PF-LED) having low p-resistivity and the highly resistive LED(HR-LED) having high p-resistivity. The result of high stress experiment shows that current crowding phenomenon is occurred from the center of between p-bonding pad and n-bonding pad to either electrodes. In addition, series resistance and optical power decrease dramatically. These results means that the resistance of between p-bonding pad and p-GaN affect reliability. That's why we need to consider the ohmic contact of p-bonding pad when design the high efficiency and high reliability LEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.697-700
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• 2004

The SBT$(Sr_{0.8}Bi_{2.4}Ta_2O_9)$ thin films for semiconductor device were deposited on Pt-coated $Pt/TiO_2/SiO_2Si$ wafer by RF magnetron sputtering method at $400[^{\circ}C]$ and annealed at the temperature range from $600[^{\circ}C]$ to $850[^{\circ}C]$. The top electrodes(Pt) were deposited on SBT thin film by DC sputtering method. The crystallinity of SBT thin films were increased with increase of annealing temperature in the temperature range of $600[{\circ}C]\sim850[^{\circ}C]$. The annealing temperature properties were to be most excellent in the case of annealed SBT thin film at $750^{\circ}C]$. And, the maximum remanent polarization$(2P_r)$ and the coercive electric field$(E_c)$ at annealing temperature of $750[^{\circ}C]$ obtained about $11.60[{\mu}C/cm^2]$ and 48[kV/cm], respectively. Specially, it was seen that fatigue properties does not change in $10^{10}$ switching cycle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1717-1723
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• 2007

In this study , quasi-MFISFET (Metal-Ferroelectric-Insulator-Semiconductor FET) devices are fabricated using PLZT(10/30/70), PLT(10), PZT(30/70) thin film and their drain current properties are investigated. It is found that the drain current of quasi-MFISFET is directly influenced by the polarization strength of ferroelectric thin fan. Also, when the gate voltages are ${\pm}5\;and\;{\pm}10V$, the memory windows are 0.5 and 1.3V, respectively. It means that the memory window is changed with the variation of coercive voltage generated by the voltage applied on ferroelectric thin film. The electric field and the leakage current with time delay of PLZT(10/30/70) thin lam are measured to investigate the retention property of MFISFET device. Some material parameters such as current density constant, $J_{ETO}$, electric field dependent factor K and time dependent factor m are obtained. The variation of charge density with time is quantitatively analyzed by using the material parameters.