title: Transparent Conductive Two-Dimensional Titanium Carbide Epitaxial Thin Films.
abstract: Since the discovery of graphene, the quest for two-dimensional (2D) materials has intensified greatly. Recently, a new family of 2D transition metal carbides and carbonitrides (MXenes) was discovered that is both conducting and hydrophilic, an uncommon combination. To date MXenes have been produced as powders, flakes, and colloidal solutions. Herein, we report on the fabrication of ∼1 × 1 cm2Ti3C2films by selective etching of Al, from sputter-deposited epitaxial Ti3AlC2films, in aqueous HF or NH4HF2. Films that were about 19 nm thick, etched with NH4HF2, transmit ∼90% of the light in the visible-to-infrared range and exhibit metallic conductivity down to ∼100 K. Below 100 K, the films' resistivity increases with decreasing temperature and they exhibit negative magnetoresistance-both observations consistent with a weak localization phenomenon characteristic of many 2D defective solids. This advance opens the door for the use of MXenes in electronic, photonic, and sensing applications.
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States ; Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Joseph
authors.initials: J
authors.lastname: Halim
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Maria R
authors.initials: MR
authors.lastname: Lukatskaya
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Cook
authors.affiliation: Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Cole R
authors.initials: CR
authors.lastname: Smith
authors.affiliation: Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Lars-Åke
authors.initials: LA
authors.lastname: Näslund
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: May
authors.affiliation: Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Hultman
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Yury
authors.initials: Y
authors.lastname: Gogotsi
authors.affiliation: Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Eklund
authors.affiliation: Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.
authors.forename: Michel W
authors.initials: MW
authors.lastname: Barsoum
references.citation: Nat Mater. 2013 Aug;12(8):754-9
references.pmid: 23749265
references.citation: Science. 2013 Sep 27;341(6153):1502-5
references.pmid: 24072919
references.citation: Proc Natl Acad Sci U S A. 2005 Jul 26;102(30):10451-3
references.pmid: 16027370
references.citation: J Am Chem Soc. 2013 Oct 30;135(43):15966-9
references.pmid: 24144164
references.citation: ACS Nano. 2012 Feb 28;6(2):1322-31
references.pmid: 22279971
references.citation: Science. 2008 Jun 6;320(5881):1308
references.pmid: 18388259
references.citation: Chem Soc Rev. 2013 Nov 7;42(21):8187-99
references.pmid: 23887238
references.citation: Adv Mater. 2014 Feb;26(7):992-1005
references.pmid: 24357390
references.citation: Adv Mater. 2011 Oct 4;23(37):4248-53
references.pmid: 21861270
references.citation: Nat Commun. 2013;4:1716
references.pmid: 23591883
references.citation: Science. 2004 Oct 22;306(5696):666-9
references.pmid: 15499015
references.citation: Nature. 2012 Oct 11;490(7419):192-200
references.pmid: 23060189
references.citation: Nat Mater. 2013 Jun;12(6):554-61
references.pmid: 23644523
references.citation: Nat Mater. 2010 May;9(5):430-5
references.pmid: 20190771
references.citation: Prog Mater Sci. 2013 Oct;58(8):1173-1243
references.pmid: 32287484
references.citation: J Am Chem Soc. 2007 Jun 27;129(25):7758-9
references.pmid: 17536805
references.citation: J Am Chem Soc. 2012 Oct 10;134(40):16909-16
references.pmid: 22989058