• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.665-671
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• 2017

Herein, we report the fabrication of low-voltage N-type organic field-effect transistors by using high capacitance fluorinated polymer gate dielectrics such as P(VDF-TrFE), P(VDF-TrFE-CTFE), and P(VDF-TrFE-CFE). Electron-withdrawing functional groups in PVDF-based polymers typically cause the depletion of negative charge carriers and a high contact resistance in N-channel organic semiconductors. Therefore, we incorporated intermediate layers of a low-k polymerto prevent the formation of a direct interface between PVDF-based gate insulators and the semiconducting active layer. Consequently, electron depletion is inhibited, and the high charge resistance between the semiconductor and source/drain electrodes is remarkably improved by the in corporation of solution-processed charge injection layers.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.13-17
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• 2014

The direct-patternable $SnO_2$ thin film was successfully fabricated by photochemical metal-organic deposition. The composition and chemical bonding state of $SnO_2$ thin film were analyzed by using X-ray photoelectron spectroscopy (XPS) from the surface to the interface with Si substrate. XPS depth profiling analysis allowed the determination of the atomic composition in $SnO_2$ film as a function of depth through the evolution of four elements of C 1s, Si 2p, Sn 3d, and O 1s core level peaks. At the top surface, nearly stoichiometric $SnO_2$ composition (O/Sn ratio is 1.92.) was observed due to surface oxidation but deficiency of oxygen was increased to the interface of patterned $SnO_2/Si$ substrate where the O/Sn ratio was about 1.73~1.75 at the films. This O deficient state of the film may act as an n-type semiconductor and allow $SnO_2$ to be applied as a transparent electrode in optoelectronic applications.

• 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.

• Journal of the Semiconductor & Display Technology
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• v.4 no.2 s.11
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• pp.1-5
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• 2005

Electon spin resonance measurements have been performed on the Mg-doped wurtzite GaN thin films grown on sapphire substrates by low-pressure metal-organic chemical vapor deposition. The sample set included films as-grown with the regular Mg doped and Mg delta doped samples and the corresponding annealed ones. The resonance signal has been observed from the annealed Mg delta-doped sample with the Lande g value of 2.029. This indicates that the singlet resonance signal originates from the neutral Mg acceptor located at 0.24 eV above the valence band edge and 0.13 eV above the Fermi level because of the nuclear hyperfine spin 1=0 of Mg and the larger value than the free electron g=2.0023.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.45-49
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• 2003

본 논문에서는 gate 산화막을 위한 Hf oxide 박막을 $Hf(dmae)_4$ (dmae=dimethylaminoethoxide) 전구체로 Direct Liquid Injection Metal Organic Chemical Vapor Deposition (DLI-MOCVD)방법을 이용하여 p-type Si(100) 기판 위에 증착하였다. 이 전구체를 이용하여 $150^{\circ}C$의 낮은 증착 온도에서도 낮은 carbon 농도와 roughness를 가지는 양질의 박막을 증착할 수 있었다. 증착된 박막은 비정질 구조를 나타내었지만 annealing 온도를 증가시킴에 따라서 결정성(monoclinic phase)을 나타내었다. $500{\AA}$으로 증착한 박막을 C-V 와 I-V curve를 통하여 전기적 특성을 평가하였다. 열처리 온도가 증가함에 따라 유효유전상수(k)는 증가하지만 열처리 온도가 $900^{\circ}C$ 이상이 되면 계면층의 형성에 의해 유효유전상수는 감소하게 되고 이에 따라 누설 전류도 감소하게 된다. 산소분위기 $800^{\circ}C$에서 annealing한 $HfO_2$ 박막의 유전상수는 20.1이고, 누설 전류 밀도는 SV에서 $2.2\times10^{-6}A/\textrm{cm}^2$ 로 좋은 전기적 특성을 가진다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.276-279
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• 2008

Air stable n-type organic field effect transistors (OFETs) based on CB60B are realized using a perfluoropolymer as the gate dielectric layer. The devices showed the field-effect mobility of $0.05\;cm^2P/V\;s$ in ambient air. Replacing the gate dielectric material by $SiO_2$ resulted in no transistor action in ambient air. Perfluorinated gate dielectric layer reduces interface traps significantly for the n-type semiconductor even in ambient air.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.346-349
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• 2009

We investigated the doping effects of $ReO_3$ in different p-type organic semiconductors on the formation of charge transfer complexes and the electrical conductivity by comparing the absorption in ultraviolet-visible-nearinfrared (UV-Vis-NIR) and the current density-voltage characteristics of the hole only devices, respectively. The large energy difference between the HOMO level of host and Fermi energy level of dopant (${\Delta}E$=$E_{HOHO,host}$ - $E_{F,dopant}$) gives higher concentration of CT complexes and enhanced conductivity.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.199-204
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• 2012

Organic thin-film transistors (OTFTs) have received considerable attention because their potential applications for nano-scale thin-film structures have been widely researched for large-scale integration industries, such as semiconductors and displays. However, research in developing n-type materials and devices has been relatively shortage than developing p-type materials. Therefore, we report on the fabrication of top-contact [6,6]-phenyl-C61-butyricacidmethylester (PCBM) TFTs by using three different solvent, o-dichlorobenzene, toluene and chloroform. An appropriate choice of solvent shows that the electrical characteristics of PCBM TFTs can be improved. Moreover, our PCBM TFTs with the cross-linked Poly(4-vinylphenol) dielectric layer exhibits the most pronounced improvements in terms of the field-effect mobility (${\sim}0.034cm^2/Vs$) and the on/off current ratio (${\sim}1.3{\times}10^5$) for our results. From these results, it can be concluded that solvent-modification of an organic semiconductor in PCBM TFTs is useful and can be extended to further investigations on the PCBM TFTs having polymeric gate dielectrics. It is expected that process optimizations using solution-processing of organic semiconductor materials will allow the development of the n-type organic TFTs for low-cost electronics and various electronic applications.

• ETRI Journal
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• v.35 no.4
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• pp.594-602
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• 2013

This paper proposes printed organic one-time programmable read-only memory (PROM). The organic PROM cell consists of a capacitor and an organic p-type metal-oxide semiconductor (PMOS) transistor. Initially, all organic PROM cells with unbroken capacitors store "0." Some organic PROM cells are programmed to "1" by electrically breaking each capacitor with a high voltage. After the capacitor breaking, the current flowing through the PROM cell significantly increases. The memory data is read out by sensing the current in the PROM cell. 16-bit organic PROM cell arrays are fabricated with the printed organic PMOS transistor and capacitor process. The organic PROM cells are programmed with -50 V, and they are read out with -20 V. The area of the 16-bit organic PROM array is 70.6 $mm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.3
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• pp.180-184
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• 2017

In this study, we examine the electrical properties of diketopyrrolopyrrole (DPP) containing polymer semiconductors that have been reported to show high performance with ambipolar characteristics. We prepared three different DPP based polymer semiconductors (PDPPTPT, PDPP3T, and PDPP2T-TT) and fabricated organic thin film transistors (OTFTs) with ambipolar polymer semiconductors as an active layer. All three DPP polymers showed only p-type properties at initial measurements. However, after annealing in vacuum oven for 24 hours, it was found that the DPP based polymers have both p-type and n-type properties. It is speculated that the residual impurities supposedly regarded as a strong electron trap source were eliminated during the vacuum process.