Electron mobility modulation in graphene oxide by controlling carbon melt lifetime. (December 2020)

• Record Type: Journal Article
• Authors: Gupta, Siddharth; Joshi, Pratik; Narayan, Jagdish
• Is Part Of: Carbon. Volume 170(2020)
• Page Start: 327
• Page End: 337
• Publication Date: 2020-12
• Subjects: Graphene -- Molten carbon -- Undercooling -- Mobility -- Raman spectroscopy -- Laser annealing -- Transmission electron microscopy; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2020.07.073
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: The lack of bandgap is a fundamental issue in graphene devices, which can be solved by fabricating reduced graphene oxide (rGO). However, its device integration is impeded by the elevated reduction temperature (>2000 K) requirements. Recently, we demonstrated a new approach for laser writing heavily-reduced GO by employing the nonequilibrium approach of nanosecond laser annealing (Gupta and Narayan, 2019) [1]. Here, we report on the electron mobility modulation in the liquid phase grown graphene oxide. The process involves melting and subsequent quenching of molten carbon, which triggers the first-order phase transformation of amorphous carbon (a-C) into rGO. Laser annealing at energy density above the 0.3 J/cm 2 melting threshold results in liquid-phase rGO growth on Si/SiO2 . The rGO films exhibit 26 cm 2 /V-s room-temperature electron mobility and −4.7 × 10 21 /cc charge carrier concentration on annealing near melt threshold. The heavily-reduced GO films are formed on -O- creeping in the loosely-packed low undercooled carbon melt during ultrafast quenching. We establish that -O- injection is an implicit function of melt lifetime, and a rise in melt lifetime triggers GO film regrowth with increased mobility >210 cm 2 /V-s and 2.2 × 10 19 /cc carrier concentration on annealing at 0.6 J/cm 2 . Laser annealing resolves the fundamental issues of impurities and topological defects in rGO fabrication by equilibrium-based methods, facilitating increased electron mobility in laser patterned graphene-based materials. Graphical abstract: Image 1