Séminaire LMGP - 29/01/2019 - KIM Youngsoo

Youngsoo KIM - post-doc NanoMat Team, LMGP, Grenoble-INP, CNRS

Abstract
Graphene, two-dimensional materials consisting of carbon with honeycomb lattice, has been extensively focused on the researchers since 2009. Recently, research on graphene-based practical applications is highly increased for the next generation industries, such as flexible electronics, bio- or chemical sensors for wearable devices. Still there are many obstacles to apply graphene in practical applications, such as low conductivity and scale-up problem. To solve the problem of high resistance of graphene, doping is an essential process to engineer the conductivity and work-function of graphene, which includes substitutional atomic doping by reactive gases, electrical doping by gate bias, and chemical doping by acids or reducing/oxidizing agents. Among these, the chemical doping has been widely used due to its simple process and high doping strength. From the results of amine doped graphene, we suppose that the electron donating property of amine group (-NH2) is the origin of such intense n-doping effect. Moreover, we studied strong modulation method for enhancement of the electrical conductivity of graphene by dual-side molecular n-doping with diethylenetriamines (DETAs) on top and amine-functionalized self-assembled monolayers (SAMs) at bottom. We constructed a self-assembled monolayers (SAMs) for modification of SiO2 substrate resulting in enhancement of mobility and conductivity of graphene and SAMs with different functional groups show different temperature dependence in electrical properties. On the other side, we studied the mass-productive graphene films synthesized by roll-to-roll chemical vapor deposition (RTR-CVD), which enabled to achieve increasing production rate of graphene films with high quality toward solving scale-up problems.

Keywords: Chemical vapor deposition, Chemical doping, Graphene field effect transistor, Chemical vapor deposition, Graphene applications