title: Graphene/Si-nanowire heterostructure molecular sensors.
abstract: Wafer-scale graphene/Si-nanowire (Si-NW) array heterostructures for molecular sensing have been fabricated by vertically contacting single-layer graphene with high-density Si NWs. Graphene is grown in large scale by chemical vapour deposition and Si NWs are vertically aligned by metal-assisted chemical etching of Si wafer. Graphene plays a key role in preventing tips of vertical Si NWs from being bundled, thereby making Si NWs stand on Si wafer separately from each other under graphene, a critical structural feature for the uniform Schottky-type junction between Si NWs and graphene. The molecular sensors respond very sensitively to gas molecules by showing 37 and 1280% resistance changes within 3.5/0.15 and 12/0.15 s response/recovery times under O2 and H2 exposures in air, respectively, highest performances ever reported. These results together with the sensor responses in vacuum are discussed based on the surface-transfer doping mechanism.
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Jungkil
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Si Duk
authors.initials: SD
authors.lastname: Oh
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Ju Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Dong Hee
authors.initials: DH
authors.lastname: Shin
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Sung
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Suk-Ho
authors.initials: SH
authors.lastname: Choi