title: X-ray induced electrostatic graphene doping via defect charging in gate dielectric.
abstract: Graphene field effect transistors are becoming an integral part of advanced devices. Hence, the advanced strategies for both characterization and tuning of graphene properties are required. Here we show that the X-ray irradiation at the zero applied gate voltage causes very strong negative doping of graphene, which is explained by X-ray radiation induced charging of defects in the gate dielectric. The induced charge can be neutralized and compensated if the graphene device is irradiated by X-rays at a negative gate voltage. Here the charge neutrality point shifts back to zero voltage. The observed phenomenon has strong implications for interpretation of X-ray based measurements of graphene devices as it renders them to significantly altered state. Our results also form a basis for remote X-ray tuning of graphene transport properties and X-ray sensors comprising the graphene/oxide interface as an active layer.
authors.affiliation: CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.|Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Procházka
authors.affiliation: Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Mareček
authors.affiliation: CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.|Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Lišková
authors.affiliation: CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic. cechal@fme.vutbr.cz.|Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic. cechal@fme.vutbr.cz.
authors.forename: Jan
authors.initials: J
authors.lastname: Čechal
authors.affiliation: CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.|Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Šikola