title: Photoinduced C-C reactions on insulators toward photolithography of graphene nanoarchitectures.
abstract: On-surface chemistry for atomically precise sp(2) macromolecules requires top-down lithographic methods on insulating surfaces in order to pattern the long-range complex architectures needed by the semiconductor industry. Here, we fabricate sp(2)-carbon nanometer-thin films on insulators and under ultrahigh vacuum (UHV) conditions from photocoupled brominated precursors. We reveal that covalent coupling is initiated by C-Br bond cleavage through photon energies exceeding 4.4 eV, as monitored by laser desorption ionization (LDI) mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) gives insight into the mechanisms of C-Br scission and C-C coupling processes. Further, unreacted material can be sublimed and the coupled sp(2)-carbon precursors can be graphitized by e-beam treatment at 500 °C, demonstrating promising applications in photolithography of graphene nanoarchitectures. Our results present UV-induced reactions on insulators for the formation of all sp(2)-carbon architectures, thereby converging top-down lithography and bottom-up on-surface chemistry into technology.
authors: Physik-Department, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.
authors: Carlos-Andres
authors: CA
authors: Palma
authors: Katharina
authors: K
authors: Diller
authors: Reinhard
authors: R
authors: Berger
authors: Alexander
authors: A
authors: Welle
authors: Jonas
authors: J
authors: Björk
authors: Jose Luis
authors: JL
authors: Cabellos
authors: Duncan J
authors: DJ
authors: Mowbray
authors: Anthoula C
authors: AC
authors: Papageorgiou
authors: Natalia P
authors: NP
authors: Ivleva
authors: Sonja
authors: S
authors: Matich
authors: Emanuela
authors: E
authors: Margapoti
authors: Reinhard
authors: R
authors: Niessner
authors: Bernhard
authors: B
authors: Menges
authors: Joachim
authors: J
authors: Reichert
authors: Xinliang
authors: X
authors: Feng
authors: Hans Joachim
authors: HJ
authors: Räder
authors: Florian
authors: F
authors: Klappenberger
authors: Angel
authors: A
authors: Rubio
authors: Klaus
authors: K
authors: Müllen
authors: Johannes V
authors: JV
authors: Barth