title: High-mobility anisotropic transport in few-layer γ-B28films.
abstract: Recent reports of successful synthesis of atomically thin boron films have raised great prospects of discovering novel electronic and transport properties in a new type of 2D materials. Here we show by first-principles calculations that monolayer and bilayer γ-B28films are intrinsically metallic while the thicker films possess intriguing electronic states that exhibit moderate to large bandgaps in all the interior layers but are nearly gapless at the surface. Remarkably, these surface electronic states are tunable by strain, allowing the outermost layer to transition between a semimetal and a narrow-gap semiconductor. Moreover, these surface states almost exclusively occupy a wide energy range around the Fermi level, thus dominating the electronic transport in γ-B28films. The dispersions of the surface electronic bands are direction sensitive, and with hole injection producing anisotropic and very high carrier mobility up to 104 cm2V-1s-1. Surprisingly, surface passivation can open a sizable bandgap, which offers an additional avenue for effective band engineering and explains the experimental observation of a large bandgap in the synthesized film. These results make few-layer γ-B28films desirable candidate materials for catalysis and electronics applications.
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology, Garden Point Campus, QLD 4001, Brisbane, Australia. liangzhi.kou@qut.edu.au and Integrated Materials Design Centre (IMDC), School of Chemical Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Liangzhi
authors.initials: L
authors.lastname: Kou
authors.affiliation: Department of Physics and Earth Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Yandong
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, Am Falturm 1, 28359 Bremen, Germany.
authors.forename: Liujiang
authors.initials: L
authors.lastname: Zhou
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology, Garden Point Campus, QLD 4001, Brisbane, Australia. liangzhi.kou@qut.edu.au.
authors.forename: Ziqi
authors.identifier: http://orcid.org/0000-0002-4777-4017
authors.initials: Z
authors.lastname: Sun
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology, Garden Point Campus, QLD 4001, Brisbane, Australia. liangzhi.kou@qut.edu.au.
authors.forename: Yuantong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology, Garden Point Campus, QLD 4001, Brisbane, Australia. liangzhi.kou@qut.edu.au.
authors.forename: Aijun
authors.initials: A
authors.lastname: Du
authors.affiliation: Integrated Materials Design Centre (IMDC), School of Chemical Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Sean
authors.initials: S
authors.lastname: Smith
authors.affiliation: Department of Physics and Astronomy and High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154, USA.
authors.forename: Changfeng
authors.initials: C
authors.lastname: Chen