title: Ultraclean suspended monolayer graphene achieved by in situ current annealing.
abstract: Ultraclean graphene is essential for studying its intrinsic transport properties or fabricating high-performance electronic devices. Unfortunately, the contamination on graphene is unavoidable after microelectromechanical system processing. Here, we report an in situ current-annealing method for achieving ultraclean suspended monolayer graphene. The charge mobility of cleaned graphene reached a surprising 3.8 × 105cm2V-1s-1, one of the highest values ever reported. For the first time, the process of current annealing was recorded under a high-resolution electron scanning microscope. It was demonstrated that temperature was the only dominant factor of the current-annealing process. Meanwhile, the mobility of suspended graphene was found to be highly sensitive to structural defects. The mobility decreased by a factor of over 100 after ion irradiation on graphene. The results revealed the underlying mechanism of current annealing on graphene and provided an effective means of preparing ultraclean graphene membranes.
authors.affiliation: Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan.
authors.forename: Haidong
authors.initials: H
authors.lastname: Wang
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takamatsu