title: Focused-laser-enabled p-n junctions in graphene field-effect transistors.
abstract: With its electrical carrier type as well as carrier densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light-graphene interactions, indirect effects arising from induced charge traps underneath the photoactive graphene arising from light-substrate interactions must be better understood and harnessed. Here, we study the local doping effect in graphene using focused-laser irradiation, which governs the trapping and ejecting behavior of the charge trap sites in the gate oxide. The local doping effect in graphene is manifested by large Dirac voltage shifts and/or double Dirac peaks from the electrical measurements and a strong photocurrent response due to the formation of a p-n-p junction in gate-dependent scanning photocurrent microscopy. The technique of focused-laser irradiation on a graphene device suggests a new method to control the charge-carrier type and carrier concentration in graphene in a nonintrusive manner as well as elucidate strong light-substrate interactions in the ultimate performance of graphene devices.
authors.affiliation: Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747, Republic of Korea.
authors.forename: Young Duck
authors.initials: YD
authors.lastname: Kim
authors.forename: Myung-Ho
authors.initials: MH
authors.lastname: Bae
authors.forename: Jung-Tak
authors.initials: JT
authors.lastname: Seo
authors.forename: Yong Seung
authors.initials: YS
authors.lastname: Kim
authors.forename: Hakseong
authors.initials: H
authors.lastname: Kim
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Lee
authors.forename: Joung Real
authors.initials: JR
authors.lastname: Ahn
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Lee
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Chun
authors.forename: Yun Daniel
authors.initials: YD
authors.lastname: Park
mesh_terms: D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry* / Q000528:radiation effects*; D007834:Lasers; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D010316:Particle Size; D013499:Surface Properties / Q000528:radiation effects; D014173:Transistors, Electronic
chemical_list: D006108:Graphite