Original Article
  • Measurements of the Temperature Coefficient of Resistance of CVD-Grown Graphene Coated with PEI

  • Soomook Lim*, Ji Won Suk*†

  • * School of Mechanical Engineering, Sungkyunkwan University, Korea

  • PEI가 코팅된 CVD 그래핀의 저항 온도 계수 측정

  • 임수묵*· 석지원*†

  • This article is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

There has been increasing demand for real-time monitoring of body and ambient temperatures using wearable devices. Graphene-based thermistors have been developed for high-performance flexible temperature sensors. In this study, the temperature coefficient of resistance (TCR) of monolayer graphene was controlled by coating polyethylenimine (PEI) on graphene surfaces to enhance its temperature-sensing performances. Monolayer graphene grown by chemical vapor deposition (CVD) was wet-transferred onto a target substrate. To facilitate the interfacial doping by PEI, the hydrophobic graphene surface was altered to be hydrophilic by oxygen plasma treatments while minimizing defect generation. The effect of PEI doping on graphene was confirmed using a back-gated field-effect transistor (FET). The CVD-grown monolayer graphene coated with PEI exhibited an improved TCR of -0.49(±0.03) %/K in a temperature range of 30~50oC


최근 웨어러블 소자를 이용한 신체와 주변 온도의 실시간 모니터링에 대한 수요가 급격히 증가하고 있다. 그래핀 기반 써미스터가 고성능 유연 온도 센서로 개발되어 왔다. 본 연구에서는 단일층 그래핀의 온도 측정 성능을 개선하기 위하여 표면에 polyethylenimine(PEI)를 코팅하여 저항 온도 계수(TCR)를 조절하였다. 화학기상증착법(CVD)에 의해 합성한 단일층 그래핀은 습식 전사 공정을 통해 원하는 기판에 전사되었다. PEI에 의한 계면 도핑을 유도하기 위하여, 소수성의 그래핀 표면을 산소 플라즈마 처리를 통해 결함을 최소화하면서 친수성으로 제어하였다. PEI 도핑 효과를 전계효과트랜지스터(FET)를 이용하여 확인하였다. PEI 도핑에 의해서 CVD 그래핀의 TCR 값이 30~50oC의 온도 범위에서 -0.49(±0.03)%/K로 향상된 것을 확인하였다


Keywords: 그래핀(Graphene), 저항 온도 계수(Temperature coefficient of resistance), 도핑(Doping), 온도 센서(Temperature sensor)

This Article

Correspondence to

  • Ji Won Suk

  • School of Mechanical Engineering, Department of Smart Fab. Technology, SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Korea

  • E-mail: jwsuk@skku.edu