Unconventional transport through graphene on SrTiO₃: a plausible effect of SrTiO₃ phase-transitions

Surajit Saha; Orhan Kahya; Manu Jaiswal; Amar Srivastava; Anil Annadi; Jayakumar Balakrishnan; Alexandre Pachoud; Chee-Tat Toh; Byung-Hee Hong; Jong-Hyun Ahn; T Venkatesan; Barbaros Özyilmaz

doi:10.1038/srep06173

Unconventional transport through graphene on SrTiO₃: a plausible effect of SrTiO₃ phase-transitions

Sci Rep. 2014 Aug 22:4:6173. doi: 10.1038/srep06173.

Authors

Affiliations

¹ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore [3].
² 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2].
³ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Graphene Research Center, National University of Singapore, Singapore 117542, Singapore [3] Department of Chemistry, National University of Singapore, Singapore 117543, Singapore [4].
⁴ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.
⁵ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] NUS Graduate School for Integrative Sciences and Engineering (NGS), Singapore 117456, Singapore.
⁶ Department of Physics, National University of Singapore, Singapore 117542, Singapore.
⁷ Department of Chemistry, Seoul National University, Seoul 152742, Korea.
⁸ School of Electrical and Electronic Engineering, Yonsei University, Seoul 120749, Korea.
⁹ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore [3] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore.
¹⁰ 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore [3] Graphene Research Center, National University of Singapore, Singapore 117542, Singapore [4] NUS Graduate School for Integrative Sciences and Engineering (NGS), Singapore 117456, Singapore.

Abstract

High-k dielectric oxides are supposedly ideal gate-materials for ultra-high doping in graphene and other 2D-crystals. Here, we report a temperature-dependent electronic transport study on chemical vapor deposited-graphene gated with SrTiO₃ (STO) thin film substrate. At carrier densities away from charge neutrality point the temperature-dependent resistivity of our graphene samples on both STO and SiO₂/Si substrates show metallic behavior with contributions from Coulomb scattering and flexural phonons attributable to the presence of characteristic quasi-periodic nano-ripple arrays. Significantly, for graphene samples on STO substrates we observe an anomalous 'slope-break' in the temperature-dependent resistivity for T = 50 to 100 K accompanied by a decrease in mobility above 30 K. Furthermore, we observe an unusual decrease in the gate-induced doping-rate at low temperatures, despite an increase in dielectric constant of the substrate. We believe that a complex mechanism is at play as a consequence of the structural phase transition of the underlying substrate showing an anomalous transport behavior in graphene on STO. The anomalies are discussed in the context of Coulomb as well as phonon scattering.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.