title: Fabrication of unipolar graphene field-effect transistors by modifying source and drain electrode interfaces with zinc porphyrin.
abstract: We report a unipolar operation in reduced graphene oxide (RGO) field-effect transistors (FETs) via modification of the source/drain (S/D) electrode interfaces with self-assembled monolayers (SAMs) of 5-(4-hydroxyphenyl)-10,15,20-tri-(p-tolyl) zinc(II) porphyrin (Zn(II)TTPOH) molecules. The dipolar Zn(II)TTPOH molecules at the RGO/platinum (Pt) S/D interface results in an increase of the electron injection barrier and a reduction of the hole-injection barrier. Using dipole measurements from Kelvin probe force microscopy and highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) calculations from cyclic voltammetry, the electron and hole injection barriers were calculated to be 2.2 and 0.11 eV, respectively, indicating a higher barrier for electrons, compared to that of holes. A reduced gate modulation in the electron accumulation regime in RGO devices with SAM shows that unipolar RGO FETs can be attained using a low-cost, solution-processable fabrication technique.
authors.affiliation: Centre of Excellence in Nanoelectronics, IIT Bombay, Mumbai 400076, Maharashtra, India.
authors.forename: Mrunal A
authors.initials: MA
authors.lastname: Khaderbad
authors.forename: Verawati
authors.initials: V
authors.lastname: Tjoa
authors.forename: Manohar
authors.initials: M
authors.lastname: Rao
authors.forename: Rohit
authors.initials: R
authors.lastname: Phandripande
authors.forename: Sheri
authors.initials: S
authors.lastname: Madhu
authors.forename: Jun
authors.initials: J
authors.lastname: Wei
authors.forename: Mangalampalli
authors.initials: M
authors.lastname: Ravikanth
authors.forename: Nripan
authors.initials: N
authors.lastname: Mathews
authors.forename: Subodh G
authors.initials: SG
authors.lastname: Mhaisalkar
authors.forename: V Ramgopal
authors.initials: VR
authors.lastname: Rao