• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.292-293
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• 2013

Sub 10-nm thick of Si plate is simulated with the software for Nanowire Field Effect Transistor (FET) device simulation. With usual single crystal Si technology, it is difficult to realize flexible electronic devices. Here, we suggest a FET device based on thinned Si layer. The simulation implied a practical limitation of the Si plate thickness for flexible devices as 2 nm. With around this thickness, Si plate may have much flexibility than existing bulk MOSFETs.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.76-80
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• 2019

The characteristics of a titanium oxide layer prepared using a plasma electrolytic oxidation (PEO) process were investigated, using an extended gate ion sensitive field effect transistor (EG-ISFET) to confirm the layer's capability to react with hydrogen ions. The surface morphology and element distribution of the PEO-processed titanium oxide were observed and analyzed using field-emission scanning-electron microscopy (FE-SEM) and energy-distribution spectroscopy (EDS). The titanium oxide prepared by the PEO process was utilized as a hydrogen-ion sensing membrane and an extended gate insulator. A commercially available n-channel enhancement MOS-FET (metal-oxide-semiconductor FET) played a role as a transducer. The responses of the PEO-processed titanium oxide to different pH solutions were analyzed. The output drain current was linearly related to the pH solutions in the range of pH 4 to pH 12. It was confirmed that the titanium-oxide layer prepared by the PEO process could feasibly be used as a hydrogen-ion-sensing membrane for EGFET measurements.

• Journal of Semiconductor Engineering
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• v.1 no.3
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• pp.88-98
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• 2020

As biosensors are widely used in the medical field, flexible devices compatible with live animals have aroused great interest. Especially, significant research has been carried out to develop implantable or skin-attachable devices for real-time bio-signal sensing. From the device point of view, various biosensor types such as field-effect transistors (FETs) and multi-electrode arrays (MEAs) have been reported as diverse sensing strategies. In particular, the flexible FETs and MEAs allow semiconductor engineering to expand its application, which had been impossible with stiff devices and materials. This review summarizes the state-of-the-art research on flexible FET and MEA biosensors focusing on their materials, structures, sensing targets, and methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.432-432
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• 2009

본 연구에서는 HW-PLD(Hot-walled Pulsed Laser Deposition) 법을 이용하여 ZnO 나노와이어를 $Al_2O_3$ 기판 위에 성장하였다. 성장된 ZnO 나노와이어는 SEM, XRD, PL 분석을 통하여 구조적 특성을 확인하였으며, 성장된 나노와이어를 photolithography 공정을 통하여 FET(Field Effect Transistor)소자를 제작하였다. 제작된 소자의 I-V 특성 측정 결과 Ti/Au 전극과 ZnO nanowire 채널 간에 ohmic 접합이 형성된 것을 확인하였으며 게이트 전압의 증가에 따라 소스와 드레인 사이의 전류가 증가하는 전형적인 n-type FET소자 특성을 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.294.1-294.1
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• 2016

Transition metal dichalcogenides (TMDs) with two-dimensional layered structure, such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2), are considered attractive materials for future semiconductor devices due to its relatively superior electrical, optical, and mechanical properties. Their excellent scalability down to a monolayer based on the van der Waals layered structure without surface dangling bonds makes semiconductor devices based on TMD free from short channel effect. In comparison to the widely studied transistor based on MoS2, researchs focusing on WSe2 transistor are still limited. WSe2 is more resistant to oxidation in humid ambient condition and relatively air-stable than sulphides such as MoS2. These properties of WSe2 provide potential to fabricate high-performance filed-effect transistor if outstanding electronic characteristics can be achieved by suitable metal contacts and doping phenomenon. Here, we demonstrate the effect of two different metal contacts (titanium and platinum) in field-effect transistor based on WSe2, which regulate electronic characteristics of device by controlling the effective barreier height of the metal-semiconductor junction. Electronic properties of WSe2 transistor were systematically investigated through monitoring of threshold voltage shift, carrier concentration difference, on-current ratio, and field-effect mobility ratio with two different metal contacts. Additionally, performance of transistor based on WSe2 is further enhanced through reliable and controllable n-type doping method of WSe2 by triphenylphosphine (PPh3), which activates the doping phenomenon by thermal annealing process and adjust the doping level by controlling the doping concentration of PPh3. The doping level is controlled in the non-degenerate regime, where performance parameters of PPh3 doped WSe2 transistor can be optimized.

• ETRI Journal
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• v.39 no.1
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• pp.62-68
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• 2017

In this paper, we present the design and characterization analysis of a cascode GaN field-effect transistor (FET) for switching power conversion systems. To enable normally-off operation, a cascode GaN FET employs a low breakdown voltage (BV) enhancement-mode Si metal-oxide-semiconductor FET and a high-BV depletion-mode (D-mode) GaN FET. This paper demonstrates a normally-on D-mode GaN FET with high power density and high switching frequency, and presents a theoretical analysis of a hybrid cascode GaN FET design. A TO-254 packaged FET provides a drain current of 6.04 A at a drain voltage of 2 V, a BV of 520 V at a drain leakage current of $250{\mu}A$, and an on-resistance of $331m{\Omega}$. Finally, a boost converter is used to evaluate the performance of the cascode GaN FET in power conversion applications.

• Journal of Adhesion and Interface
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• v.22 no.3
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• pp.91-97
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• 2021

By introducing an organic interlayer on the Parylene C dielectric surface, the electrical device performances and the operating stabilities of organic field-effect transistors (OFETs) were improved. To achieve this goal, hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (ODTS), as the organic interlayer materials, were used to control the surface energy of the Parylene C dielectrics. For the bare case used with the pristine Parylene C dielectrics, the field-effect mobility (μ_FET) and threshold voltage (V_th) of dinaphtho[2,3-b:2',3'-f ]thieno[3,2-b]- thiophene (DNTT) FET devices were measured at 0.12 cm²V^-1s^-1 and - 5.23 V, respectively. On the other hand, the OFET devices with HMDS- and ODTS-modified cases showed the improved μ_FET values of 0.32 and 0.34 cm²V^-1s^-1, respectively. More important point is that the μ_FET and V_th of the DNTT FET device with the ODTS-modified Parylene C dielectric presented the smallest changes during a repeated measurement of 1000 times, implying that it has the most stable operating stability. The results could be meaned that the organic interlayer, especially ODTS, effectively covers the Parylene C dielectric surface with alkyl chains and reduces the charge trapping at the interface region between active layer and dielectric, thereby improving the electrical operating stability.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1035-1038
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• 2013

Rolling circle amplification (RCA) of DNA on an aligned-carbon nanotube (a-CNT) surface was electrically interfaced by the a-CNT based filed effect transistor (FET). Since the electric conductance of the a-CNT will be dependent upon its local electric environment, the electric conductance of the FET is expected to give a very distinctive signature of the surface reaction along with this isothermal DNA amplification of the RCA. The a-CNT was initially grown on the quartz wafer with the patterned catalyst by chemical vapor deposition and transferred onto a flexible substrate after the formation of electrodes. After immobilization of a primer DNA, the rolling circle amplification was induced on chip with the a-CNT based FET device. The electric conductance showed a quite rapid increase at the early stage of the surface reaction and then the rate of increase was attenuated to reach a saturated stage of conductance change. It took about an hour to get the conductance saturation from the start of the conductance change. Atomic force microscopy was used as a complementary tool to support the successful amplification of DNA on the device surface. We hope that our results contribute to the efforts in the realization of a reliable nanodevice-based measurement of biologically or clinically important molecules.

• Electrical & Electronic Materials
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• v.17 no.8
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• pp.3-12
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• 2004

유기 박막 트랜지스터 (Organic Thin film Transistors ； 이하 OTFT)는 1986년부터(1) 반도체 장치의 새로운 부류로 급속하게 발전해 오고 있다. 반도체 산업에 있어 이러한 유기물질의 큰 발전은 1947년에 있었던 최초의 inorganic FET (Field Effect Transistor) 탄생에 버금갈 만한 성과라고 여겨진다.(중략)

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.11a
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• pp.14.2-14.2
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• 2006