• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.1
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• pp.35-42
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• 1989

Electrical properties of both a monolayer at the air/water interface and Langmuir-Blodgett films sandwiched between aluminum electrodes are studied using a current-measuring technique. A change in induced charges on an electrode suspended in the air was measured in combination with the surface area isotherm in the electrical measurement of the monolayer. A change in induced charges on an electrode is measured while heating the sample in the electrical measurement of the LB films. From both measurements, we elucidated that a spontaneous polarization plays very important role in the electrical properties of both a monolayer at the air/water interface and LB films sandwiched between aluminum electrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.79-82
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• 1994

We have manufacture Copper-tetra-tert-butylphalocyanine (CuTBP)Langmuir-Blodgett(LB) films, which is known be sensitive to NO$_2$ gab. A response of these films to the NO$_2$ gab was studied. A surface pleasure of 25mN/m was obtained as a proper one for a film deposition. A deposited film status was identified with Uv/visible absorption spectra, ellipsometry measurements, and current-voltage(I-Y) characteristics. The NO$_2$ gas response experiments under 200ppm conducentration show that there are increment of electrical conductivity by 12 times, 5 seconds of response time, and 5 seconds of response time, and 90 seconds of recovery time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.5-8
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• 1997

A study on the electrical conduction characteristics of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir- Blodgett(LB) technique has recently been attracted interest as a method of the deposition ultrathin films. We hate fabricated N-docosyl N\`-methyl viologen-diTCNQ(DMVT) anion radical LB film and investigated the molecular orientation and electrical conduction characteristics. We have measured infrared transmission-reflection spectra. The alkyl chain is found to he well-ordered with the tilt angle of 13$^{\circ}$ with respect to the substrate surface normal and the TCNQ plane is tilted at 76$^{\circ}$ the surface normal. In ESR spectrum, we confirmed that a half-amplitude linewidth is clearly dependent on the incident angle, which indicates conducting species change. The in-plane conductivity of 31 lagers is approximately 1.33$\times$10$^{-6}$ S/cm. The ohmic behaviour was observed below 0.6 V, when current-voltage(I-V) characteristics was measured verically.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.234-236
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• 1994

We fabricated Au/PI/Pb and Au/PI/1-layer Arachidic acid/Pb structures in order to electron transport properties through the junctions. It was found that 9-layer PI LB films function as a good tunneling barrier from the I-V properties. And several peaks originating in the vibrational modes of the constituent molecules of 1-layer arachidicacid LB films were clearly observed in $d^2V/dI^2-V$ curves.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.84-87
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• 2020

The properties of ultra-thin two-dimensional (2D) organic ferroelectric Langmuir-Blodgett (LB) films of the poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] were investigated to find possible applicability in flexible and wearable electronics applications. In the C-V characteristics of the MFM capacitor of 2-monolayer of 5 nm films, a butterfly hysteresis curve due to the ferroelectricity of P(VDF-TrFE) was confirmed. Typical residual polarization value was measured at 2μC/㎠. When the MFM capacitor with ultra-thin ferroelectric film was measured by applying a 10 Hz bipolar pulse, it was shown that 65% of the initial polarization value in 105 cycles deteriorated the polarization. The leakage current density of the 2-monolayer film was maintained at about 5 × 10-8 A/㎠ for the case at a 5MV/cm electric field. The resistivity of the 2-monolayer film in the case at an electric field at 5 MV/cm was more than 2.35 × 1013 Ω·cm.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.23-29
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• 2019

A copper tetracumylphenoxy phthalocyanine (CuPccp) thin film was formed on an organic insulator film by Langmuir-Blodgett (LB) deposition for gas sensor fabrication. To increase the reproducibility of film transfer, stearyl alcohol was used as a transfer promoter. The structural properties of the CuPccp layers were optically monitored through attenuated total reflection and polarization-modulated ellipsometry techniques. The average thickness of a single layer of the CuPccp LB film was measured to be 2.5 nm. Despite the role of the transfer promoter, the stability of the layer transfer was not sufficient to ensure homogeneity of the LB film. This was probably due to the presence of aggregates in the molecular structure of the CuPccp LB film. Nevertheless, copper phthalocyanine polymorphism can be greatly suppressed by the LB arrangement, which appears to contribute to the improvement of electrical conductivity. The p-type semiconductor characteristics were confirmed by Hall measurements from the CuPccp LB films.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.172-178
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• 1997

Polyaniline(PANI)-stearic acid(SA) composite monolayer was formed at the air-water interface. The stearic acid as a surfactant was used to promote PANI monolayer formation. Uniform PANI-SA monolayer assemblies with Y type and transfer ratio of ca. 1 were fabricated using the Langmuir-Blodgett(LB) technique. The PANI-SA composite LB films with high electrical conductivity of $10^{-1}{\sim}10^{-2}S/cm$ were obtained by doping of HCl or $I_2$, and their conductivity revealed essentially close value as that of conventional PAHI-HCl complex. Especially, iodine is found to be the most promising dopant, since it gives a remarkable stability for the application as a polymer electrode in the MIM molecular device consisted of acceptor, sensitizer, and donor. The structure and physical properties of PANI-SA LB films were investigated through the near-ir UV, FT-IR, and Cyclic voltammetry.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1193-1196
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• 1993

Electrical properties of $C_{22}$-Quinolium(TCNQ) Langmuir-Blodgett(LB) films are reported depending on a type of applied voltage on a type of applied voltage and temperature. A conductivity was identified to be anisotropic with a ratio of ${\sigma}||/{\sigma}{\bot}{\simeq}10^7$ at room temperature. The I-V characteristics along the film surface direction show an ohmic behavior up to a few hundred volts. But the I-V characteristics in the vertical direction display an ohmic behavior for low-electric field, and a nonohmic behavior for high-electric field. This nonohmic behavior has already been interpreted as a conduction mechanism of space-charge limited current and Schottky effect near the electric-field strengh of $10^6$ V/cm. When the electric field exceeds further, there is anormalous phenomia similiar to breakdown. From the study of I-V characteristics with the application of step or pulse voltage, we have found that the breakdown voltage shifts to higher one as the step or pulse interval becomes shorter. These results indicate that the breakdown is due to both electrical and thermal effect. To see the infulence of temperature, current was measured as function of temperature with several bias voltages, which are lower than that of breakdown. It shows that the current increases about 3 orders of magnitude near $60{\sim}70^{circ}C$, and remains constant for a while up to $140^{\circ}C$ and then suddenly drops. Arahidic acid was used to cmpare with $C_{22}$-Quinolium(TCNQ) LB films.

• Electrical & Electronic Materials
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• v.8 no.2
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• pp.151-157
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• 1995

Frequency-dependent electrical properties of $C_{22}$-Quinolinium(TCNQ) LB films were investigated in a frequency range of 10[Hz]-13[MHz] along a perpendicular direction. The films were heat-treated to understand an electrodynamic response in a temperature range of 20-240[.deg. C]. Frequencydependent dielectric constants show that there are two characteristic dispersions; one is a dispersion occuring near 1[MHz] coming from the orientational polarization of the molecules and the other one is an interfacial polarization effect below 1[kHz] or so when the annealing temperature is above 80 [.deg. C]. The overall frequency-dependent dielectric constant is higher near 80[.deg. C]. It may be due to a softness of the alkyl chains. Several other methods were employed to identify the internal structure change of the films. DSC(differential scanning calorimetry) data of the $C_{22}$-Quinolinium(TCNQ) molecules shows that there is an endothermic process near 110[.deg. C] and a weak exothermic process near 180[.deg. C]. While the endothermic process is related to a disordering of the alkyl chains, the exothermic process seems to be due to a chemical structure change of the TCNQ molecules. Thickness measurement by ellipsometry shows that there is a thickness drop near 100[.deg. C], and the thickness above 120[.deg. C] becomes around 20[%] of the room-temperature value.lue.

• Polymer Science and Technology
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• v.3 no.6
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• pp.489-505
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• 1992