• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.561-561
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• 2012

Graphene, two dimensional single layer of carbon atoms, has tremendous attention due to its superior property such as fast electron mobility, high thermal conductivity and optical transparency, and also found many applications such as field-effect transistors (FET), energy storage and conversion, optoelectronic device, electromechanical resonators and chemical sensors. Several techniques have been developed to form the graphene. Especially chemical vapor deposition (CVD) is a promising process for the large area graphene. For the electrically isolated devices, the graphene should be transfer to insulated substrate from Cu or Ni. However, transferred graphene has serious drawback due to remaining polymeric residue during transfer process which induces the poor device characteristics by impurity scattering and it interrupts the surface functionalization for the sensor application. In this study, we demonstrate the characteristics of solution-gated FET depending on the removal of polymeric residues. The solution-gated FET is operated by the modulation of the channel conductance by applying a gate potential from a reference electrode via the electrolyte, and it can be used as a chemical sensor. The removal process was achieved by several solvents during the transfer of CVD graphene from a copper foil to a substrate and additional annealing process with H2/Ar environments was carried out. We compare the properties of graphene by Raman spectroscopy, atomic force microscopy(AFM), and X-ray Photoelectron Spectroscopy (XPS) measurements. Effects of residual polymeric materials on the device performance of graphene FET will be discussed in detail.

• 접착 및 계면
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• 제22권3호
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• pp.91-97
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• 2021

본 연구는 Parylene C 유전체 표면에 유기 자기조립단분자막(self-assembled monolayer, SAM) 중간층을 도입함으로써 표면특성을 제어하고 최종적으로 유기전계효과 트랜지스터(organic field-effect transistors, OFETs)의 전기적 안정성을 향상시킨 결과를 제시하였다. 유기 중간층을 적용함으로써, Parylene C 게이트 유전체의 표면 에너지를 제어하였으며, OFET의 가장 중요한 성능변수인 전계효과 이동도(field-effect transistor, μ_FET)와 문턱 전압 (threshold voltage, V_th)의 성능향상과 구동 안정성을 증대시켰다. 단순히 Parylene C 유전체를 적용한 Bare OFET에서 μ_FET 값은 0.12 cm²V^-1s^-1가 측정되었으나, hexamethyldisilazane (HMDS)과 octadecyltrichlorosilane (ODTS)를 중간층으로 적용된 소자에서는 각각 0.32과 0.34 cm²V^-1s^-1로 μ_FET가 증가하였다. 또한 1000번의 transfer 특성의 반복측정을 통해 ODTS 처리한 OFET의 μ_FET와 V_th의 변화가 가장 작게 나타남을 확인하였다. 이 연구를 통해 유기 SAM 중간층, 특히 ODTS는 효과적으로 Parylene C 표면을 알킬 사슬로 덮어 극성도를 낮춤과 함께 전하 트래핑을 감소시켜 소자의 전기적 구동 안정성을 증가시킬 수 있음을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.637-640
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• 2008

The properties of oriented poly(3-hexylthiophene-2,5-diyl) in field effect transistors (FETs) have been investigated through mechanical stretching process as the original. Silicon-based FETs shown high mobility of $0.02\;cm^2/V$ s after thermal treatment and $0.0092\;cm^2/V$ s at r.t. PET-based FETs were expected to show a similar performance in mobility to that of silicon-based FETs.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1319-1321
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• 2009

Copper phthalocyanine (CuPc) Field-effect transistors (FETs) was successfully fabricated on plastic substrates. Orientation of CuPc crystallites on substrate could be obtained via rubbing process. It was revealed that CuPc crystallites were perpendicularly aligned on PES substrates with the rubbing direction. The performance of FETs was affected by orientation of CuPc on rubbed substrates.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.642-642
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• 2013

Graphene, two dimensional single layer of carbon atoms, has tremendous attention due to its superior property such as high electron mobility, high thermal conductivity and optical transparency. Especially, chemical vapor deposition (CVD) grown graphene has been used as a promising material for high quality and large-scale graphene film. Unfortunately, although CVD-grown graphene has strong advantages, application of the CVD-grown graphene is limited due to ineffective transfer process that delivers the graphene onto a desired substrate by using polymer support layer such as PMMA(polymethyl methacrylate). The transferred CVD-grown graphene has serious drawback due to remaining polymeric residues generated during transfer process, which induces the poor physical and electrical characteristics by a p-doping effect and impurity scattering. To solve such issue incurred during polymer transfer process of CVD-grown graphene, various approaches including thermal annealing, chemical cleaning, mechanical cleaning have been tried but were not successful in getting rid of polymeric residues. On the other hand, lithographical patterning of graphene is an essential step in any form of microelectronic processing and most of conventional lithographic techniques employ photoresist for the definition of graphene patterns on substrates. But, application of photoresist is undesirable because of the presence of residual polymers that contaminate the graphene surface consistent with the effects generated during transfer process. Therefore, in order to fully utilize the excellent properties of CVD-grown graphene, new approach of transfer and patterning techniques which can avoid polymeric residue problem needs to be developed. In this work, we carried out transfer and patterning process simultaneously with no polymeric residue by using a metal etch mask. The patterned thin gold layer was deposited on CVD-grown graphene instead of photoresists in order to make much cleaner and smoother surface and then transferred onto a desired substrate with PMMA, which does not directly contact with graphene surface. We compare the surface properties and patterning morphology of graphene by scanning electron microscopy (SEM), atomic force microscopy(AFM) and Raman spectroscopy. Comparison with the effect of residual polymer and metal on performance of graphene FET will be discussed.